# Wide Rims? Don't believe the hype...



## oldranger (Apr 14, 2011)

Hi Folks, 
After researching the subject of rim specs for DH wheels, I find that wider rims are becoming increasing popular. News Flash, right? No, not really, but I have begun to wonder just how much of this is simply hype. Let's be honest and see if there are some facts we can look at before I even give my opinion:

1) Many of the most popular tires with consistently good reviews (i.e. Maxxis Minion DHF) have casings that were designed before manufacturers were building these 'wide' rims with >25mm internal width.
2) Many of the top racers use rims with less than 25mm internal width.

Really? You mean the really fast guys don't ride on wide rims? Why not? I know from personal experience that 'wide' rims feel different, but honestly I don't know if they make me faster. *So: I think it is all hype. My guess is that the ideal rim width for DH tires on the market today is 23mm - 25mm of internal width.*

2013 winning riders

Steve Smith - Easton Havoc 23mm
Greg Minnaar - Enve DH 21mm (30mm external)
Aaron Gwin - DT FR600 24.9mm

I've ridden these rims on Freeride, DH Racing and DS:

Crossmax SX 21mm
Atomlab Standard Issue 21mm
Atomlab Pimp2 26mm
Specialized Roval DH 23mm

Unrelated, but I've ridden DT Swiss m480 for All Mountain
DT m480 19.6mm

My opinion: I notice a different feel when moving from 21mm to 23mm rims (internal width) and I up the psi a bit on the rear&#8230;but I don't know if it is actually better traction or just a different feel. My experience is far from a controlled experiment. I don't even really notice the different from 23mm to 26mm.


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## bholwell (Oct 17, 2007)

A greater difference will be felt when running thinner, AM or XC tires at lower pressures.

Yes, I designed the DHR2 and the HR2 on a 23mm internal width rim, but the difference in profile going from 23mm to 28mm internal isn't much.


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## Guest (Feb 24, 2014)

we are not all racers or wanna be racers but mere plain recreational riders by in large so much of what you posted does not apply nor will effect the vast majority.


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## meltingfeather (May 3, 2007)

that's a broad proclamation on a pretty weak basis.

here's an idea: why not ride what you like and what works for you, regardless of what Smith and Minnaar are riding?


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## FastBanana (Aug 29, 2013)

I can tell the difference between a 21 and a 30. 

However, for I run 21mm on my AM bike. Its does just fine with beefy tires, but i could run a lighter tire on a wider rim. DH is much different than trail riding. They run much stronger but heavier tires that really dont care what rims they are on. Also, going very wide can squared out the profile of the tire, which is a bad thing when you lean the bike 60+ degrees

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## edubfromktown (Sep 7, 2010)

We all have different objectives so whatever works...

I noticed a difference between running 19mm (Stan's 355) and 21.?mm (Stan's Crest) internal width rims with the same tires mounted on them.

I have 3 sets of "28mm" rims (~23 ish mm internal width) as well and do not notice as much of a difference with the same tire mounted on them as compared to the Crest's. All of them are setup tubeless. 

I even run a 3.0 Knard 120 tpi front tire mounted on a "28mm" rim (rigid single speed 36x18). It makes the rim look like a road wheel with all the tire volume. Quite effective cushion (@ ~12 psi with a bit of added weight and +2-3 cog teeth to pedal it on the climbs I was doing with a 2.4 front tire/15t cog).


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## mtnzj (Mar 13, 2009)

oldranger said:


> 2013 winning riders
> 
> Steve Smith - Easton Havoc 23mm
> Greg Minnaar - Enve DH 21mm (30mm external)
> Aaron Gwin - DT FR600 24.9mm


Don't forget these guys have to run their sponsor's equipment, and many of the mainstream manufacturers have not gone to the wider rims (partially due to old rim safety specifications).

Additionally, the world's top pro riders would kick ass on most any bike/setup you stick under them.


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## evasive (Feb 18, 2005)

I've never seen anyone claim that wide rims are faster, so I don't see the relevance. The benefit most often cited is the more traction through the use of lower pressures. I doubt any DH racers are willing to risk using lower pressures. On the odd occasion I enter an enduro race, I definitely add pressure to my tires.


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## oldranger (Apr 14, 2011)

bholwell said:


> Yes, I designed the DHR2 and the HR2 on a 23mm internal width rim, but the difference in profile going from 23mm to 28mm internal isn't much.


Thanks bholwell! This is the kind of information I was hoping to get out of this thread!

Note: I didn't intend this to be a discussion on what 'I liked to run' or what 'is fun for me' since that doesn't really matter to you (folks). I hoped to initiate (or instigate) a debate on the actual performance value of wider rims. I haven't found (anywhere) where an engineer or product team has substantianted that a rim wider than 23mm (internal) helps improve riding or how a tire provides traction. On the flip side I see that wider rims increase material and weight, or they require expensive materials....all of which are a drawback in my mind.


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## oldranger (Apr 14, 2011)

mtnzj said:


> Don't forget these guys have to run their sponsor's equipment, and many of the mainstream manufacturers have not gone to the wider rims (partially due to old rim safety specifications).
> 
> Additionally, the world's top pro riders would kick ass on most any bike/setup you stick under them.


I totally agree. But I was honestly surprised when I researched what they are riding - and learned they are NOT running the trendy wide rims.

Look folks. My bike is not spec'd with what the racers are using simply because it is what they are using. I have Atomlab wheels, a Marz 888 fork, low-end cranks, a heavy-a## seat, and the list goes on...but if I am going to spend money on improving my bike it seemed like wheels were the way to go. So I started looking at what credible riders are winning on.


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## FastBanana (Aug 29, 2013)

oldranger said:


> Thanks bholwell! This is the kind of information I was hoping to get out of this thread!
> 
> Note: I didn't intend this to be a discussion on what 'I liked to run' or what 'is fun for me' since that doesn't really matter to you (folks). I hoped to initiate (or instigate) a debate on the actual performance value of wider rims. I haven't found (anywhere) where an engineer or product team has substantianted that a rim wider than 23mm (internal) helps improve riding or how a tire provides traction. On the flip side I see that wider rims increase material and weight, or they require expensive materials....all of which are a drawback in my mind.


Wide rims dont directly provide traction, they enable lower pressures that provide more traction.

Do you really notice 50g in a rim? Tire choice is almost infinitely more important.

Sent from my LG-LS995 using Tapatalk


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## oldranger (Apr 14, 2011)

FastBanana said:


> Do you really notice 50g in a rim? Tire choice is almost infinitely more important.


Thanks for your points on how rim width can influence psi (and traction). I don't recall mentioning 50g, but for the sake of discussion:

I run a 630 gram Atomlab Pimp2 rim because I was encouraged to build a wide, tough rim for DH. If I go with a smaller rim profile I can get closer to 500g. The top end Norco, Devinci and Specialized DH bikes are spec'd with rims that weigh about 500g and are close to 23mm internal width. (I think; just picking from some brands)


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## Berkeley Mike (Jan 13, 2004)

This has been said about many "advancements" in bike technology. The challenge is that measuring it's effect is elusive. Its sort of like taking 20 grams off of a derailleur; an incremental step I may not even feel. Add to that I'm just trying to stay upright most of the time.

But, when you take a look at an entire Groupo the weight difference adds up. And, seen from my 1988 Rigid 6 Speed Rockhopper with cantis, all those incremental steps add up, too.


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## FastBanana (Aug 29, 2013)

Thats the difference between an Arch and a Flow rim.

630g rim is just plain overkill. There is a reason those bikes are spec'ed with 500g rims. Its a great balance point, and 23mm is by no means a thin rim. At that weight/width, you have a very strong wheel.

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## Deerhill (Dec 21, 2009)

I find rims over @23-25mm internal width start to take a heck of a lot more hits on rocky trails (from the volume and also dings to the finish)


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## deerock (Nov 4, 2013)

nvphatty said:


> we are not all racers or wanna be racers but mere plain recreational riders by in large so much of what you posted does not apply nor will effect the vast majority.


love what is said here. this forum consists of recreational riders...not many pros if any. Though it's great these guys do so well, etc. I couldn't give a wild smelly crap about who rides what. I want good wheels that feel great on my ride....and I'm a damned good rider. But I don't pretend to be a pro or anything similar.


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## Bike Whisperer (Aug 7, 2012)

I ride a full rigid, what pro DH and FR riders run means jack schitt to me (and most riders).

My experience with single ply tires is that big volume tires on narrow rims roll when cornering unless I pump them up harder than I prefer. So I like wider rims with big tires that I can run down to ~18psi for traction and some cushion.


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## MTBMILES (Dec 27, 2007)

I personally like wider rims for running lower pressure and getting better traction and less tire squirm. 
Are you going to tell me this is all in my head?


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## blcman (Feb 1, 2007)

^ This! Bike Whisperer wins the prize for best answer!


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## FastBanana (Aug 29, 2013)

MTBMILES said:


> I personally like wider rims for running lower pressure and getting better traction and less tire squirm.
> Are you going to tell me this is all in my head?
> 
> Sent from my iPhone using Tapatalk


Its great for running over chihuahuas
....with less tire squirm

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## dirtrider76 (Sep 19, 2012)

Meh, my wide rims are awesome. I dont care what pro's run, I'm not a pro.


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## oldranger (Apr 14, 2011)

MTBMILES said:


> I personally like wider rims for running lower pressure and getting better traction and less tire squirm.
> Are you going to tell me this is all in my head?


I dunno. My hypothesis (for the sake of debate) is that the ideal rim width for standard 2.3-2.5 width DH tires on the market today is 23mm - 25mm of internal width. I looked for any shred of evidence to the contrary, and didn't find any. Maybe when tires are squirming psi is sub-optimal, and addressing it with wider rims doesn't solve the root of the problem.


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## meltingfeather (May 3, 2007)

FastBanana said:


> Also, going very wide can squared out the profile of the tire, which is a bad thing when you lean the bike 60+ degrees


lol... when you're leaning your bike over 60(+) degrees... good one. :skep:

also... tire profiles are round... always.


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## meltingfeather (May 3, 2007)

oldranger said:


> I looked for any shred of evidence to the contrary, and didn't find any.


That being pros' equipment choices?
Just out of curiosity, how did you arrive at your claimed optimal rim width?
And what is sub-optimal about riding a tire pressure that works? Isn't optimum tire pressure totally dependent on the circumstances, including rim width, or have you also figured out optimum tire pressure for everyone on every bike?


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## oldranger (Apr 14, 2011)

meltingfeather said:


> Just out of curiosity, how did you arrive at your claimed optimal rim width?


To your question: I based my hypothesis largely on the observation that the majority of the major manufacturers spec their best DH bikes with 23mm-25mm rims, and many of the DH racing teams use the same. I had no access to wheel manufacturer test data. They do. A hypothesis is a speculative guess that has yet to be tested.

That said, after a day of interesting comments, I'd like to restate my hypothesis because I think some of you missed it: *the ideal rim width for DH tires on the market today is 23mm - 25mm of internal width*. I started this thread in hopes there would be attempts to prove or disprove it&#8230;which in turn, help me make a good decision on a pair of wheels for my DH bike. I recognize it's not a well justified hypothesis, and the word "ideal" oversimplifies things&#8230;but the point I'm making has not been disproven in this thread. On the contrary, a tire designer seems to (indirectly) support it and that is the only professional opinion so far on the thread. Maybe I should try to elaborate a bit on what I mean by ideal: I mean compatible with, and works optimally in conjunction with a conventional DH tire (2.3-2.5 DH casing) to provide the best possible traction for the rider without adversely impacting speed or durability. "Ideal" for DH is not: wide enough to enable dramatically low psi so the rider doesn't perceive slip on rocks and roots and such. Or worse&#8230;so the rider can sit down comfortably.

Let's not dumb this down. I threw this topic out in a forum dedicated to Wheels & Tires. This discussion isn't about preference, or Recreation vs. Racing, or how something feels. I consider myself a recreational rider. But frankly folks - if you are a "recreational rider" sitting on a $4-8K DH bike&#8230;you're sitting on a sophisticated, carefully spec'd piece of equipment. And most of you try to go fast (I hope). Me personally: I don't want to ignorantly do the equivalent of throwing a big ass set of Dubs on a BMW M3 just because of some hype around 'WIDE is BETTER' and manufacturers like I9, Atomlab, Spank, etc. wanting to sell us those things. It is a common play to penetrate a market with gimmicky products that owners can't find as OE on some car or truck or gun or bike - under the premise it is better.

Here are the observations I have that seem to contribute to this topic.

Major Manufacturer DH Bike Spec:
•	Trek Session - FR600 (24.9mm)
•	Devinci Wilson, Norco Aurum LE, Transition TR450 - Easton Havoc DH (23mm)
•	Specialized Demo 8 - Roval 30mm external (usually means about 23mm internal)
•	GT Fury - E13 LG1+ DH (23mm)
•	Giant Glory 0 - DT Swiss EX500 (20.7mm)
Successful Racing Team Rim Choices:
•	Steve Smith - Easton Havoc (23mm)
•	Greg Minnaar - Enve DH 21mm (30mm external)
•	Aaron Gwin - DT Swiss FR600 (24.9mm)


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## oldranger (Apr 14, 2011)

meltingfeather said:


> Isn't optimum tire pressure totally dependent on the circumstances, including rim width, or have you also figured out optimum tire pressure for everyone on every bike?


Absolutely. Tire pressure is the variable that the rider should change based on conditions. No. I haven't made any claims about psi, nor have I stated that I've figured out anything.


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## evasive (Feb 18, 2005)

Fine, but your OP wasn't carefully caveated and specific like your last post. It's easy to miss your point when you don't make it. The OP was a broad claim about wide rims being all hype, and used a fairly small sample based on pro DH riders as the supporting evidence. 

Your OP mentions that you're looking at DH rims, but that's the only hint that the discussion of rim width was intended to be limited to that narrow application. Besides, most of the wider is better talk that would be interpreted as hype comes from the trail-AM market where you have Stans and WTB and Syncros playing.


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## MTBMILES (Dec 27, 2007)

I have noticed wheel sizes changing and bikes have disc brakes, droppers and FS. I have a feeling rims widths are also evolving. 


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## oldranger (Apr 14, 2011)

evasive said:


> Fine, but your OP wasn't carefully caveated and specific like your last post. It's easy to miss your point...


Progressive elaboration. And c'mon...the acronym "DH" is in my first sentence. Now do you have something to contribute that disproves my hypothesis Mr. Evasive, or are you just looking to easily increase your post count with a debate? Please do some research.



evasive said:


> Besides, most of the wider is better talk that would be interpreted as hype comes from the trail-AM market where you have Stans and WTB and Syncros playing.


OK, I hadn't thought about where the hype was coming from. For what its worth, I bought Stans Flow EX for my son's DH bike...believing the hype applied to DH. The 2.5 Maxxis Minion DHF tire profile on that rim is absolutely different than it is on my Crossmax SX or My Atomlab Standard Issue. Which is better? (I don't know, hence my hypothesis and provocative posts and title)


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## MTBMILES (Dec 27, 2007)

Have you not ridden the different widths to come up with a conclusion based on riding?


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## oldranger (Apr 14, 2011)

MTBMILES said:


> Have you not ridden the different widths to come up with a conclusion based on riding?


Yes, but as I mentioned in my original post...I couldn't get to any conclusion about what is really faster. I've ridden rims from 21mm 26mm (internal width) in many places across North America, as fast as I can go. But my opinion isn't worth much so I started looking for credible information.


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## MTBMILES (Dec 27, 2007)

I think better traction equals more confidence leading to faster times. That is my conclusion based on my riding. 


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## meltingfeather (May 3, 2007)

oldranger said:


> I started this thread in hopes there would be attempts to prove or disprove it&#8230;which in turn, help me make a good decision on a pair of wheels for my DH bike.


You know what would be a much better basis for a decision than theoretical arguments on the internet? Finding some wide rims to borrow/demo and see what you think.


oldranger said:


> On the contrary, a tire designer seems to (indirectly) support it and that is the only professional opinion so far on the thread.


I think you have misinterpreted his comment somewhat.

Hypotheses are part of the scientific method. You aren't using any scientific methods. You are attempting to confirm your bias by searching out anecdotal evidence that you interpret to support your idea. No isolation. No control. It is meaningless.
You can't prove whether something is "all hype" or not. First, what does that even mean? Second, you'll never have enough data to say anything statistically significant, and even if you were able to put all that together, it would not tell you what your individual experience is going to be on any given rim width. That's why it makes sense to cut all the BS and just ride some wide rims and see what you think. It would also be a whole lot more fun, unless posting here is more fun to you than riding.



oldranger said:


> Let's not dumb this down.


It started off dumbed down. Why change now? :arf:

At some point you have to realize that your, from a scientific standpoint, totally hack efforts at really "figuring something out" aren't going anywhere. Riding a bike for the sake of it is about doing what works for you, which riding the bike will tell you. Doing otherwise is posing.


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## oldranger (Apr 14, 2011)

Mr. Feather, 
Do you have some objective observations or proposed investigation that constructively adds to this? Do you suggest a specific rim or rim width based on your own observations?

This is a hypothesis, not a theory, so you can back down on "start doing some science" rant. I don't pose. I'm not a professional I don't have a good opinion. Don't get so easily bent out of shape on how I instigated folks to contribute to this thread

A hypothesis is defined as: a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.


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## kiloman (Feb 14, 2012)

meltingfeather said:


> that's a broad proclamation on a pretty weak basis.
> 
> here's an idea: why not ride what you like and what works for you, regardless of what Smith and Minnaar are riding?


Word. :thumbsup:

Based on feedback from others and reflection on my personal intended use and preferences I decided on a set of Pacenti TL28 29er rims to replace the stock wheels on my 2009 Giant XTC 29er 1.

I don't know if I'd go so far as to call it "hype" but I would say they lived up to my expectations based on other users feedback. (IMO WIDE carbon rims are "hype.") The Pacenti TL28 29er are reasonably light. I can run low pressures with them (20psi F and 22psi R on my pump) and haven't pinch flatted on them, with tubes (passed plenty of people in the Shenandoah 100 who did pinch flat on the rocks for whatever reason so I know my setup works for me). And at those pressures they offer good tire stability. But this is only my second set of MTB rims, so I have no valid comparison. All I can say is they work for me, other users experience might be different based on their intended use, riding style, and priorities. So do your research and make an informed decision.


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## oldranger (Apr 14, 2011)

meltingfeather said:


> You know what would be a much better basis for a decision than theoretical arguments on the internet? Finding some wide rims to borrow/demo and see what you think.


OK. Done. I have two seasons of DH racing on a set of Atomlab Pimp2 rims with 2.5 Minion DHF front and rear; sometimes High Rollers. I have not substantially changed my approach to psi while using these rims. These rims have a 26mm (WIDE) internal width

I have 6 days of sustained riding at Whistler on the same bike, but with rims that had a 23mm internal width.

I can't tell the difference. Should I stick with a 23mm rim or go with a wider one? if so why? If you want to make this about me (like your attacks on my words in this post)...I'm 190-195lbs riding weight, I ride fast and want to go as fast as I can. What rims should I consider?


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## oldranger (Apr 14, 2011)

(This is fun by the way - I do appreciate the responses. There have been some meaningful comments) (Thank you)


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## meltingfeather (May 3, 2007)

oldranger said:


> Mr. Feather,
> Do you have some objective observations or proposed investigation that constructively adds to this?


Yes. Riding will tell you all you need to know about what equipment choice will work for you.


oldranger said:


> Do you suggest a specific rim or rim width based on your own observations?


I know what works for me, which is of no use to you.



oldranger said:


> This is a hypothesis, not a theory, so you can back down on "start doing some science" rant. I don't pose. I'm not a professional I don't have a good opinion. Don't get so easily bent out of shape on how I instigated folks to contribute to this thread


Not at all bent... I just offered my opinion, which is what you asked for. Don't like it? Don't heed my advise.



oldranger said:


> A hypothesis is defined as: a supposition or proposed explanation made on the basis of limited evidence as a* starting point for further investigation*.


Cute. I know what a hypothesis is. I'd say, as others have, that what I ride and for that matter what sponsored pros ride is of little value in determining "optimal" for you.
Good luck :thumbsup:


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## deerock (Nov 4, 2013)

there's too much time on your hands. go ride your bike.


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## HoJo (Jan 26, 2004)

Sure seems like oldranger=Traildoc. For those who didn't follow the Az forum Traildoc was an avid rider, trail-builder and troll. Who was temporarily banned from the local Sedona forest and then banned from MTBR. There is way too much good information on this forum let's keep the good exchange and forget the trolls.
hojo


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## dbabuser (Jan 5, 2004)

Bike manufacturers spec bikes to fit the average rider. It's up to you to figure out where you fit in relation to the average. In my experience, being heavier and more aggressive than the average rider, a wider and heavier rear rim lasts longer. Is 600 grams overkill? Not for me (185 lbs, former expert dh racer), unless I want to rebuild the rear wheel 1 or more times per season.


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## oldranger (Apr 14, 2011)

HoJo said:


> Sure seems like oldranger=Traildoc.
> hojo


Still hoping for someone to give specifics on rim widths outside of the 23mm - 25mm range for DH.

Too funny. Trail doc? Really? I'm just a 42 year (Old) guy who has been a Ranger (Ranger) Old+Ranger = OldRanger. You guys really stink at science and math.


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## oldranger (Apr 14, 2011)

dbabuser said:


> In my experience, being heavier and more aggressive than the average rider, a wider and heavier rear rim lasts longer. Is 600 grams overkill? Not for me (185 lbs, former expert dh racer), unless I want to rebuild the rear wheel 1 or more times per season.


Thanks. Do you run a lighter rim in the front? I've considered that option.


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## dbabuser (Jan 5, 2004)

I've had good luck w/ 500g front rims on my dh bike.


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## oldranger (Apr 14, 2011)

Thanks dbabuser. This is helpful, I haven't tried a 'staggered' setup...but wondered if it would be a good approach for DH riding given the typical weight distribution front/rear the rider has. It's also helpful for me to have your benchmark for a 185 pound rider - that's about where I am. I have seen others with this approach

For anyone (like me) who may be new to this topic of rim widths, or rim design in general - let me try to elaborate on the relationship between dbabuser's observations on rim weights and rim widths (simple, I know). Generally speaking rims with 21mm internal widths can be built in the 500g range (i.e. DT Swiss EX500). Rims with a 25mm internal width can generally be built in the 600g range (i.e. DT Swiss EX600). I use the DT Swiss example since they are kind enough to put the rim weight in the product name.

Disclaimer: this doesn't always hold true. One contrast is the Stan's Flow EX which has a 25.5mm inner width, but only weights 500g.


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## 92gli (Sep 28, 2006)

oldranger said:


> Yes, but as I mentioned in my original post...I couldn't get to any conclusion about what is really faster.


You keep saying faster. Its not always about "faster" for non-racers. I like the wider trend because the tire is more stable at lower pressures.


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## leeboh (Aug 5, 2011)

MTBMILES said:


> I personally like wider rims for running lower pressure and getting better traction and less tire squirm.
> Are you going to tell me this is all in my head?
> 
> Sent from my iPhone using Tapatalk


I don't run 26er downhill tires. I do however run 29er 2.4 tires on 35 mm ID rims and they are awesome at lower pressure and maximum traction. Wider = better for tubeless, YRMV.


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## Ilyam3 (Nov 21, 2011)

With the modern frames and drive for short chain stains with bigger wheels (27.5) that are sometimes stuffed in smaller frames (HDR ) the width of the rim can be a problem with the fit in the rear. Manufacturers already spec narrow 2.2 tires for tight clearance so going wider might not be an option
On the other hand I agree with op For modern 2.4 -2.5 tires the internal width of 23-25 mm is optimal for weight and performance. And I can run low pressures on ust rims of that width too , so why carry extra weight for 35-40mm internal big rim. That's unless we go to 2.7 or 3.0 tires , oh wait - that's fat biking


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## Guest (Feb 25, 2014)

Ilyam3 said:


> That's unless we go to 2.7 or 3.0 tires , oh wait - that's fat biking


no thats not close to fat biking, 3.8 begins fatness. When i build my next full squish AM bike it'll use 35mm blunts with the 26" 2.75 dirt wizards which will equate to 27.5 circumference wise.


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## brimorga (Jul 23, 2013)

Carbon rims are lighter than tires. So use a wider rim and a more narrow tire to get a similar effect as a fat tire and a narrow rim for less weight.

Simple.


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## ryanxj (Sep 9, 2011)

Road bikes.
Motorcycles.
Cars. 
Zamboni. 
Wheelbarrows. 
Unicycles.
Wheelchairs. 
Space Shuttles.
GoKarts. 
Mars rover.
Trailers. 
Hand trucks. 
Lawnmowers.
Aircraft.
Strollers.
Tractors. 
R/C anything.
Golf carts.
Heavy equipment. 
ATV's.
UTV's.
Monster trucks.

_*DID I MISS ANY?*_

*NOT ONE* of these rubber tire equipped machines utilizes a rim width that is narrower (by much of a margin) than the tire it is supporting... _*COINCIDENCE?*_

Why believe the hype when you can look at the facts?

Oh, and dont believe the hype, 9ers dont ride faster and suspension will actually slow you down from all the pedal bob....


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## oldranger (Apr 14, 2011)

ryanxj said:


> _*DID I MISS ANY?*_
> 
> *NOT ONE* of these rubber tire equipped machines utilizes a rim width that is narrower (by much of a margin) than the tire it is supporting... _*COINCIDENCE?*_


Yes, I think you missed one: Motocross. I don't have one, but those machines still use tires with a rim width that is narrower than the tire it is supporting. It looks like the margin is greater on the front. But I'm way out of my knowledge 'base' on this MX comparison.

But you could also add one to your list: BMX Bikes. Those tires seem to be fairly close to the rim width. Wait, let me clarify: those 20" tires that roll on hard pack or paved dry surfaces have tires with a casing width close to the rim width. Hmmm. I wonder when BMXers will go to full suspension 29ers cause they ride faster?

Your comments where thought provoking - so thanks for that!


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## oldranger (Apr 14, 2011)

Link to another post on here that has some relevance to this subject:
http://forums.mtbr.com/wheels-tires/tire-height-vs-rim-width-756818.html


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## oldranger (Apr 14, 2011)

*I found some more related posts*

Try this one:
http://forums.mtbr.com/wheels-tires/rim-width-how-wide-too-wide-882258.html

A quote from that thread:


Norman Clydesdale said:


> As the rim's interior width increases, you'll see different performance and appearances in your tires. Basically, the same tire will sit and perform differently on a narrower rim vs an even slightly wider rim...On a 25mm inner width rim, the tire sits noticeable squarer and hooks up better in corners in all conditions. I can run it tubeless at 32psi in the front and 36 in the rear and not worry about burping or dinging the rim. If I run just a few psi lower in a tubeless set up on the 25inner width rim, I'll ding and flat spot the rims.
> So, you'll need to factor in PSI, tire size, and rim width in to the equation. Depending on tire choice and preferred PSI, I think you can go too wide in rim width. In my experience,25-23mm inner width seems to be a good spot for many trail tires in the 2.4-2.3 range. Just a few mm increase in inner rim width can produce positive performance results.


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## edubfromktown (Sep 7, 2010)

oldranger said:


> Try this one:
> http://forums.mtbr.com/wheels-tires/rim-width-how-wide-too-wide-882258.html
> 
> A quote from that thread:


32 / 36 PSI is quite high pressure for a large percentage of riders ... Norman Clydesdale implies 200+ lb. rider and based on what he stated, there wasn't much room to lower the tire pressure without dinging the rims.

Some other factors to consider besides PSI, tire size and rim width:

Tubeless system
Tire sidewall thickness
Rider weight
Riding style
Terrain

I am 195 lbs. and ran 20 psi F / 25 psi R "semi-aggressively" on Stan's 355 rims with TLR Schwalbe Racing Ralph tires (2.4 front / 2.25 rear) setup tubeless w/ Stan's goo and rim tape. I manged to burp the front once on a severe down and up that was off camber (with a bit of a turn). That was the only time I've ever burped a tubeless tire in years of riding on them.

I can run 17 PSI on the front with a wider Stan's Flow rim running with a Schwalbe Nobby Nic snakeskin 2.35 tire. I typically run a Racing Ralph 2.4 a few PSI higher on the front...

My approach to setting up appropriate tire pressure is:

Front- start in mid 20's, drop 1 PSI at a time and ride a bit until handling in significant turns becomes squirmy, then add 1-2 psi.

Rear- start around 30, drop 1 PSI at a time and ride a bit until I detect something close to a rim hit when riding over rocks/roots at a moderate pace, then add 1-2 PSI.


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## Saul Lumikko (Oct 23, 2012)

People, you are forgetting one important reason to run wide rims.

The sheer surface area you get for flashy colors!


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## ryanxj (Sep 9, 2011)

oldranger said:


> Yes, I think you missed one: Motocross. I don't have one, but those machines still use tires with a rim width that is narrower than the tire it is supporting. It looks like the margin is greater on the front. But I'm way out of my knowledge 'base' on this MX comparison.
> 
> But you could also add one to your list: BMX Bikes. Those tires seem to be fairly close to the rim width. Wait, let me clarify: those 20" tires that roll on hard pack or paved dry surfaces have tires with a casing width close to the rim width. Hmmm. I wonder when BMXers will go to full suspension 29ers cause they ride faster?
> 
> Your comments where thought provoking - so thanks for that!


What part of 'motorcycles' excludes MX? and I'm not sure on bmx stuff myself, but if they are using narrow rims, i would have to assume that its purely a matter of shaving grams, as is likely @ the top level of dh racing. Not to mention, if assume that the smooth groomed nature of a bmx track allows for highish pressures, lessening the benefits of a wider rim/tire interface...


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## googas7070 (Jan 2, 2014)

I guess this thread means my Sun Rhyno Lites are back in style!:thumbsup:


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## Bike Whisperer (Aug 7, 2012)

Saul Lumikko said:


> People, you are forgetting one important reason to run wide rims.
> 
> The sheer surface area you get for flashy colors!


Ding, ding, ding...winning

1994 called and wanted it's wide rims...just need some nice green hubs


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## LB412 (Nov 28, 2012)

Most of the expansion has to do with the relatively recent tubeless tire trend. Burping will occur more frequently on older rim tire combos because neither were designed for the task. Primarily because a narrow tire base generally leads to a taller thinner tire when inflated. Think narrow at the bottom and wide at the top... Equals more stress on the bead in hard turns or landings. By widening the base you theoretically reduce flex on the tire and therefore the bead. That said we are heading into marketing overkill territory. My 24.9 internal works great.


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## oldranger (Apr 14, 2011)

LB412 said:


> Most of the expansion has to do with the relatively recent tubeless tire trend...By widening the base you theoretically reduce flex on the tire and therefore the bead.


Thanks for your contribution.

This gets me thinking (or wildly speculating as some have written). As bholwell noted early on in this thread - he designed DHR2 and the HR2 on a 23mm internal width rim. He also stated that "_going from 23mm to 28mm internal isn't much_". I'm pretty sure those tires are 2.4 width; they also have Tubeless Ready casing options. Anyway, I'm just reiterating the point that a tire is designed with a specific rim width that is optimal.

Taking LB412's point: think about a tubeless rim manufacturer (like Stan's for example). They need to get a majority of the TR tires on the market to simply hold air well...even before they start to analyze how tires function in other ways on their rim. Unless a tubeless rim manufacturer are working together for an ideal tubeless wheel (rim+tire), it's not unreasonable to question whether they are building rims outside of the ideal width of most tire casings...simply to get them to hold air better.

So I have an idea: let's look at one of the newer DH tires (since the OP is about DH tires). Let's try the new 2014 Schwalbe Magic Mary 26 x 2.35. Does anyone know what rim width that tire was designed to work with?


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## oldranger (Apr 14, 2011)

By the way, based on information I've gathered online and input on this thread: for my new set of DH wheels I'm considering a DT Swiss FR600 rim (25mm wide) and trying a tubeless ready tire like the 2.35 width Magic Mary. If I had the courage I would go with an EX500 front rim...

I'm used to running relatively high pressures. I'm 185lbs without gear and I run 28-30psi front and 32-34 psi rear depending on the track. Last two years I used 26mm wide AtomLab Pimp2's with DT Champion spokes, Minion DHF, and an XC Tube (Heavy!!)


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## Deerhill (Dec 21, 2009)

*haven't tried magic mary..*

Muddy Marry was one of my fav fronts, good girth and worked great on a 25mm rim. Wouldn't surprise me if some of those Schwalby were designed w/ 25mm or wider rim in mind, casings are nice size


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## changingleaf (Apr 2, 2010)

Like bholwell, tire designer said "the difference in profile going from 23mm to 28mm internal isn't much".

A wider rim should give more lateral stability at the same air pressure because it is increasing the air-volume in the tire.


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## leeboh (Aug 5, 2011)

oldranger said:


> Thanks for your contribution.
> 
> This gets me thinking (or wildly speculating as some have written). As bholwell noted early on in this thread - he designed DHR2 and the HR2 on a 23mm internal width rim. He also stated that "_going from 23mm to 28mm internal isn't much_". I'm pretty sure those tires are 2.4 width; they also have Tubeless Ready casing options. Anyway, I'm just reiterating the point that a tire is designed with a specific rim width that is optimal.
> 
> ...


 The tire/ rim companies HAVE been working together for several years now. The UST rim profile matches together with tire bead profile. Combines with a butyl ( airtight) tire liner and some stiffer sidewalls, the system works well. Some rims need a rim strip as well and the presta valves have a removable core to add sealant. For me, there is no downside to wider rims, unless you include lower tire pressure for better traction a negative.


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## oldranger (Apr 14, 2011)

*a picture is worth a thousand words*

From Schwalbe's website on their most modern tire designs for the type of riding we are discussing here. Still looks like (by design by Schwalbe) tires are significantly wider than the rims.

I wonder how wide these rims are?
















This image is from a section where they describe some design elements of the Super Gravity carcass








Super Gravity: Revolutionary carcass technology for MTBs | Schwalbe North America


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## MTBMILES (Dec 27, 2007)

It seems most riders like the wider rims so maybe you should "believe the hype". I do. 


Sent from my iPhone using Tapatalk


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## Bike Whisperer (Aug 7, 2012)

MTBMILES said:


> It seems most riders like the wider rims so maybe you should "believe the hype". I do.
> 
> Sent from my iPhone using Tapatalk


Yes, I've rode anywhere from 17mm to 30mm internal with roughly the same width tire. I greatly prefer the 30mm internal. I recently switched from 23mm to 30mm internal on the same tire and prefer the 30mm. There is zero hype here, just my real world on the bike experience...YMMV

:thumbsup:


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## DethWshBkr (Nov 25, 2010)

oldranger said:


> Yes, I think you missed one: Motocross. I don't have one, but those machines still use tires with a rim width that is narrower than the tire it is supporting. It looks like the margin is greater on the front. But I'm way out of my knowledge 'base' on this MX comparison.
> 
> But you could also add one to your list: BMX Bikes. Those tires seem to be fairly close to the rim width. Wait, let me clarify: those 20" tires that roll on hard pack or paved dry surfaces have tires with a casing width close to the rim width. Hmmm. I wonder when BMXers will go to full suspension 29ers cause they ride faster?
> 
> Your comments where thought provoking - so thanks for that!


Typcailly a rear rim width for a 250 2 stroke/450 4 stroke is 2.15" (tire is 110mm or 4.33"), front rim is usually 1.6", (tire 80mm or 3.15").
Tire width makes a pretty big difference on them regarding turn in capabilities, due to the curvature of the tread. 
Having a much narrower front wheel also allows the bike to "drop" into corners beautifully. Something we don't do on the mountain bikes. We run the same tire widths on the mountain bikes, front or rear, sometimes with a wider tire in the front.....


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## oldranger (Apr 14, 2011)

*Comment from Syntace Website on their W35 rim*

Per Syntace:

_With a rim width (inner) of 28.4 mm the Syntace W35 will provide the „RightTireShape" for tyres up to 2.5" tyre width.

*Less pressure, more control*

Less tyre pressure means: more grip, less rolling resistance in rough terrain, higher capability to absorb impacts, higher speed in corners as well as better braking traction. Why can a wider rim be ridden with less air pressure? Because the carcass remains upright better and is in contact with the rim via more air volume. On the wide Syntace W35 MX rims, mountain bike tyres mount wider and more directly on the rim with less "bulging" than on previous conventional narrow rims with low support width. This significantly reduces the tendency of "folding" when running low air pressures.

*For everything but downhill*

Meanwhile we are able to confirm from several years of experience: Syntace W-Series wheels can do everything. Apart from deliberately caused pinch flats with a Maxxis Minion or Specialized Butcher (or similar). What we mean, is causing harsh pinch flats *using a tyre with knob profile which is unfavourable towards wide rims.* This will simply dang up the rim hook. And we will have to help out with a crash replacement ;-)_









Syntace

So, I guess Syntace would say there is such a thing as a tyre with a knob profile unfavourable towards wide rims. Tires like the Minion or the Butcher.


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## Kronk (Jan 4, 2004)

oldranger said:


> Per Syntace:
> 
> _
> So, I guess Syntace would say there is such a thing as a tyre with a knob profile unfavourable towards wide rims. Tires like the Minion or the Butcher._


_

IF you get the area between the knobs to align just right. A rim width that matches any narrower tire/rim combo can produce the same result._


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## derby (Jan 12, 2004)

With my own designs, and the p35's I ran before, I've noticed the most tire performance improvement in the 2.1 to 2.35 size single-ply tires I've tried with my 650b bike going from narrow 30mm to wider rims. 

By performance improvement, I mean much improved traction and stability, and reduction in rolling resistance on rocky trail. And not to mention a set of my rim's ~300+ gram reduction in measured rim weight compared to p35's, and much stiffer wheels enhancing the feel of traction and stability.

Bigger tires are certainly improved too, but I think 2.4 and above really need 45mm wide rims for as noticeable a jump in performance gains over the truly hyped so called "wide" 30mm rims available.

With 2.4 and larger and/or double-ply I think there are diminishing returns in performance improvement with wider rims. Although duel-ply Minion riders on my 29'er x 35mm wide rims "hype" to me and in the forums around the world about their improvement in handling.

No matter how wide a rim, DH park riders and racers and large huckers need to use pretty high pressures to avoid pinch flats. The wider rim advantage may not be much for DH and FR because of the pressures required. I've also read an interview with a top DH racer who wanted rims that will dent, unlike carbon-fiber rims, when the tire is cased, so they can finish the run without flatting. 

I'm thinking real wide CF rims are more optimum for trail riding, rather than DH, where the much lighter weight is an advantage for climbing and endurance, and for the huge handling advantages at more moderate downhill speeds of public trails of real wide rims stiffening the casing tension under the cornering knobs and running lower pressures.


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## 274898 (Nov 29, 2005)

evasive said:


> I've never seen anyone claim that wide rims are faster, so I don't see the relevance. The benefit most often cited is the more traction through the use of lower pressures. I doubt any DH racers are willing to risk using lower pressures. On the odd occasion I enter an enduro race, I definitely add pressure to my tires.


Yeah, I agree. It is not like wider rims are faster, it is that they make the tire wider so the contact area is larger. If anything the grip is better. Will it make a noticeable difference? That is the question for every rider to answer themselves.

The pros use what company pays them. In the case of all the riders the OP mentioned, all of them are using the widest rims available to them from the company they are sponsored and paid by.

I think the biggest change to DH racing is gonna be wheel size and that they are gonna start moving to bigger wheels once they strengthen the bigger hoops.


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## manokaiser (Jun 30, 2008)

Here is a good article on the subject.
This should answer a lot of questions here.
I just build a pair of WTB KOM 23mm internal. I 'll figure out soon what it feels like I guess. 
Ride on...


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## SKullman (Oct 4, 2004)

oldranger said:


> Per Syntace:
> 
> _With a rim width (inner) of 28.4 mm the Syntace W35 will provide the „RightTireShape" for tyres up to 2.5" tyre width.
> 
> ...


This here is fantastic information, it explains two thing at once, tire tech and rim tech.


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## Dennis (Mar 2, 2014)

''you are wrong friend,,,the more we know about products,,and it gives us better choices,thank you,,,,,
we buy and use the better we ride


nvphatty said:


> we are not all racers or wanna be racers but mere plain recreational riders by in large so much of what you posted does not apply nor will effect the vast majority.


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## gticlay (Dec 13, 2007)

I like that a little wider rim is stronger and stays true for a longer period of time. Don't have to get cray cray about it but the old narrow rims weren't as stout. Stan's old Flow ZTR rims is super strong and light. Not sure why they felt the need to put more weight in the newer rims


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## lstone84 (Nov 15, 2012)

manokaiser said:


> Here is a good article on the subject.
> This should answer a lot of questions here.
> I just build a pair of WTB KOM 23mm internal. I 'll figure out soon what it feels like I guess.
> Ride on...


I think part of this discussion involves marketing and selling to the masses. First, the pro riders are all sponsored and mostly ride with gear from major companies, few of which make wide rims. Secondly, carbon has become much more common in the bike world, allowing reasonably light wide rims, which previously was not feasible without affordable carbon. Sure, you could make light wide carbon rims but it would be out of most peoples price range. So there wasn't really an opportunity for companies to make a big profit from this.


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## jdubside (May 6, 2010)

*28 is NOT wide, Try a derby 40mm and then make your opinion.....*

I think everyone needs to try a 40mm carbon derby on the front before making opinions to this thread... game changer.... makes a round xc tire an all mtn monster...



oldranger said:


> Hi Folks,
> After researching the subject of rim specs for DH wheels, I find that wider rims are becoming increasing popular. News Flash, right? No, not really, but I have begun to wonder just how much of this is simply hype. Let's be honest and see if there are some facts we can look at before I even give my opinion:
> 
> 1) Many of the most popular tires with consistently good reviews (i.e. Maxxis Minion DHF) have casings that were designed before manufacturers were building these 'wide' rims with >25mm internal width.
> ...


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## Pau11y (Oct 15, 2004)

"Trendy wide rims"?
I've been on D321/EX729 for 10+ years on my DH bikes... Must be the old hawtness thing?!


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## mspohn (Jan 26, 2006)

oldranger said:


> My opinion: I notice a different feel when moving from 21mm to 23mm rims (internal width) and I up the psi a bit on the rear


This quote right here shows why you feel a difference, but you're not feeling the advantage of a wider rim. If you move to a wider rim, keeping the tire constant, you are increasing the volume of the tire. Which means you have to LOWER the PSI to compare apples to apples. To make it simple, for the same PSI, increasing volume, makes the tire "harder".

If you increase tire volume, by increasing inner rim width, you can lower pressure, which will increase your traction - with the added benefit of having a more stable tire with regards to lateral (cornering) forces because of the rounder tire cross section.

This actually should also decrease rolling resistance, on anything but a smooth surface, because the tire can conform to trail features easily with less energy lost in the tire deformation and rebounding process.


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## Yody (Jan 21, 2008)

If you're a casual rider (or ridgid rider) you might like these ultra wide rims (35mm)and big squishy low pressure tires/Casings, but if your pinning it on any kind of DH, its not the ideal setup. These ultra wide rims are a fred phenomenon, and companies love freds with money. (Flamesuit on lol)


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## modifier (May 11, 2007)

Bike Whisperer said:


> I ride a full rigid, what pro DH and FR riders run means jack schitt to me (and most riders).
> 
> My experience with single ply tires is that big volume tires on narrow rims roll when cornering unless I pump them up harder than I prefer. So I like wider rims with big tires that I can run down to ~18psi for traction and some cushion.


This ^. I like fat tires at lower pressures and I find that with a fat rim they are much more predictable in corners. I think they stick better too. And I'm not talking 25. I like 35. But...that's just me.


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## Yody (Jan 21, 2008)

And rock Stikes while turning, thru rocks, with a wide run unprotected because of a stretched out tire with no sidewall bulge. .. is very dangerous at speed


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## roobydoo (Feb 29, 2012)

I think that many are not noticing a difference be because they are not going wide enough!
Ztr Flows ARE my narrow rim.
The rest of the time I run 47mm as my narrow rim and 80mm as my winter rim. Once on a fatbike, narrow is anything on a normal mtb.
Now I don't want to turn this into a fatbike vs mtb issue, but my point is. Once tire pressure become as important as it is on a fatbike you learn to try the same on your standard bike. Guess what, I'm hardly trying with guys I used to have to push myself to keep up with.

For me a narrow Mtb rim is anything less than 25mm inside, I am not fast enough to care about the grams I could save just to loose traction, a better ride, and better handling.


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## colbygee (Mar 7, 2010)

Well there is a big difference 
In rim width and performance 
Skinny rims are weeker and flexy and tires are
Squirmy ! Simple !


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## Surestick Malone (Jan 24, 2004)

DethWshBkr said:


> Typcailly a rear rim width for a 250 2 stroke/450 4 stroke is 2.15" (tire is 110mm or 4.33"), front rim is usually 1.6", (tire 80mm or 3.15").
> Tire width makes a pretty big difference on them regarding turn in capabilities, due to the curvature of the tread.
> Having a much narrower front wheel also allows the bike to "drop" into corners beautifully. Something we don't do on the mountain bikes. We run the same tire widths on the mountain bikes, front or rear, sometimes with a wider tire in the front.....


I've always understood the reason for wider rear tires on motorbikes was traction under power. Apparently they actually handle better with narrower tires. 
On a bicycle, which is way underpowered compared to a motorbike, the danger of loosing the front, which is a guaranteed crash, versus the rear in a turn means fatter tires in the front. Part of this is a lot of bikes have much more clearance in the forks than between the chainstays due to drivetrain requirements.


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## dirtrider76 (Sep 19, 2012)

jdubside said:


> I think everyone needs to try a 40mm carbon derby on the front before making opinions to this thread... game changer.... makes a round xc tire an all mtn monster...


Totally planned on it but they dont make 26 rims so I went with Velocity Blunt35's.


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## highdelll (Oct 3, 2008)

oldranger said:


> i.e. Maxxis Minion DHF


e.g. is what you wanted; not i.e.

see more -- Grammar Girl : I.e. Versus E.g. :: Quick and Dirty Tips ?


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## boostin (Apr 21, 2008)

Personally, I've found wide rims to be stabilizing. Is that good or bad? For me, I like to keep my bikes loose and flickable. This stabilizing action is not desirable. I have to work harder to get my lean on. I also still ride 26" and have flat pedals. 

I can see where the stabilizing action would be a positive trait for someone else though. I also understand that people like to run narrower tires than 2.4". The wide rims seem to be benefit tires in the 2.0-2.2 range more than than 2.4's. 

And I agree with gticlay, the original Flows were hard to beat


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## hssp (Aug 28, 2007)

Last year I was racing enduro in Norway on a not too high level, and I had Syntace W35 rims. They gave super sideways stability, but I had way more pinch flats than before - running tubeless... I had to go for SuperGravity rear for racing and a beefier than before tire for everyday riding. I did the first half of the season om Flow EX, and I hadde no problems on the same tires. When I did the switch, I measured the tires om rims with same tubes and same pressure (digital gauge): the Flow EX gave a 10mm higher and 1mm wider profile on Nobby Nic 2.4"...

A curiosity is that German Bike mag har a "dream enduro bike" test, where Liteville/Syntace brought a pimped out 301. The where running the narrower, lighter W30 rear with W35 up front in a b6-er config.. 

My own conclusion: wide rims good for stability, but not for your tube consumption...

After the season I sold my W35 wheels and stuck with the Flow EX wheels for harder riding and some Flow sized chinese carbon thingies for everyday riding. Works great for this year I hope.

I now just wait for the new dual chamber system from Schwalbe, where low pressures and no pinch flats can be a reality..


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## Lelandjt (Feb 22, 2008)

Wide rims (26-30mm internal) were popular in DH & FR from 2000ish to 2007ish. Mavic's top DH rim was 29mm internal and was a mainstay on the circuit. This was when the Minion DHF became the standard tire. Narrow rims for DH became popular when Mavic made the 823 its premier rim and riders starting looking to the NoTubes Flow and similar to reduce weight. A lot of riders were never as happy with the narrower profile but appreciate easy tubeless and having DH wheels you can sprint so the trade off was made. Now that carbon is allowing wide, light rims (and they have tubeless friendly profiles) riders are getting the best of both worlds. It's getting popular on the internet faster than on OEM and World Cup bikes because the companies making these rims are smaller and focus on aftermarket sales. Why Enve continues to cheap out and use the same mold for their DH rim and AM rim (same outside shape but more carbon for thicker walls & narrower width) is beyond me but I bet they come out with a wider 2nd gen DH rim soon now that the market is proven. Oh, and I've heard that the Syndicate uses the AM rim for its greater width & lower weight and just swaps them out when they crack.

I don't feel like re-reading the OP and proof reading mine to see if I covered his points but here's the conversation ender: Ride a set of 26 to 29mm carbon rims and just try not to prefer them to everything else.
Ultimate DH wheelset: Light Bicycle DH rims, DT 240 hubs, DT Aerolite spokes. Budget version is NoTubes Flow EX rims, Hope hubs, doubled butted spokes. For burly version substitute Mavic 729 rim.

Edit: On my DH bike I've exclusively used the Minion DHF 2.7" since like 2004. I've tested other tires but always go back to my standard. Keep in mind that the 2.7" Minion measures the same as the 2.5"s from Spesh, Conti, Bontrager, ect. I've used them on rims from 23-30mm and prefer 26-29mm.


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## jdubside (May 6, 2010)

Everyone on this thread should give a 40mm wide carbon rim a try. It is very different. In my opinion much better than easton carbon, enve carbon, and shanghai carbon, all of them I have tried, 19mm wide 28wide, and 30wide... the 40 crushes them all in handling stiffness and durability PERIOD.


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## Bike Whisperer (Aug 7, 2012)

*1980 Araya Catalog*

1980 called and wanted its 32mm wide mountain bike rims back...this is the rim (7x) that was spec'd on the original 1982 Stumpjumper.

















I think the hype was the skinny roadie width rims starting in the late 80's


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## thickfog (Oct 29, 2010)

Bike Whisperer said:


> 1980 called and wanted its 32mm wide mountain bike rims back...this is the rim (7x) that was spec'd on the original 1982 Stumpjumper.
> 
> View attachment 873902
> 
> ...


Exactly.

This thread went from dumb to really dumb. People going from 21mm to 23mm, keeping the psi the same and saying they can't feel a difference? Really Einstein?

I have a feeling too many of the contributions here never tried a proper wide rim. As another said, their flows are not even their wide rim. I couldn't agree more.

Keep running your roadie crap. Enjoy if that's what you like!


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## oldranger (Apr 14, 2011)

Thanks for your on-topic perspective Lelandjt.



Lelandjt said:


> Ultimate DH wheelset: Light Bicycle DH rims, DT 240 hubs, DT Aerolite spokes. Budget version is NoTubes Flow EX rims, Hope hubs, doubled butted spokes. For burly version substitute Mavic 729 rim.


OK - there is opportunity here. I built that exact budget version for my son's Demo 8. Thinking that since he weighs 90 pounds - the lighter spec could hold up for his riding. Next time I'm out riding DH I'll try his ZTR Flow EX/DT Competition wheels on my bike and see how they work. We use Hope hubs on all of our custom wheels.

Lelandjt - how much riding time do you have on the Light Bicycle DH rims? I am interested in those. I looked at those as I viable option until I decided I didn't believe the hype.


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## oldranger (Apr 14, 2011)

thickfog said:


> This thread went from dumb to really dumb. People going from 21mm to 23mm, keeping the psi the same and saying they can't feel a difference? Really Einstein?


This thread has over 16,000 views in 6 days. The only dumb stuff I've seen on this thread are posts from folks trying to change the subject and/or folks that misquote the OP (me). Some of you obviously don't pay attention to details. Which, by the way, is exactly what this thread is about.


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## oldranger (Apr 14, 2011)

*Checkpoint on the topic - are there carbon DH (Downhill) rim options?*

Are there any major rim manufacturers are making carbon DH rims? I know there have been a lot of good comments regarding the value of wide carbon rims for trail riding and all-mountain-spec bikes, but I'm sticking with the topic of DH.

There is one reputable manufacturer - Enve that makes a carbon DH rim. Per their website, they designed it for "faster cornering speeds, direct lines, maximum durability, and responsive accelerations". Also according to their website, Enve has been providing this carbon rim for over 4 years, and no other rim manufacturers have followed those footsteps.

Here are the Enve DH Rim Technical Specs:
- Hole Counts: 32
- External Width: 30mm
- Internal Width: 21mm
- Depth: 31mm
- Weight: 475 g
- Spokes: DT Competition

ENVE Composites Launches the First All‐Carbon DH Rim - Press Releases - Vital MTB


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## Bike Whisperer (Aug 7, 2012)

oldranger said:


> Are there any major rim manufacturers are making carbon DH rims? I know there have been a lot of good comments regarding the value of wide carbon rims for trail riding and all-mountain-spec bikes, but I'm sticking with the topic of DH.
> 
> There is one reputable manufacturer - Enve that makes a carbon DH rim. Per their website, they designed it for "faster cornering speeds, direct lines, maximum durability, and responsive accelerations". Also according to their website, Enve has been providing this carbon rim for over 4 years, and no other rim manufacturers have followed those footsteps.
> 
> ...


Not sure if you consider Light-Bicycle a "major" rim manufactuer, but they have come out with a heavier duty DH version of their 33mm wide carbon rim



> For Downhill version, we add much more carbon fiber to make the rim strong enough. So the weight is heavier than All Mountain version. It is around 460+/-15g.
> 
> Advantages of this newly 33mm wide MTB 26er carbon rim
> *Wider & deeper( 33mm wide and 30mm deep), the strength and stiffness is much improved.
> ...


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## clbaumer (Oct 21, 2013)

Just a thought;

This seems, to me, like it will be the same argument as 26" vs 29", but then eventually will come to an agreement that the middle is realistically the best. I haven't rode on real wide rims yet, but I have a feeling that eventually all will agree in the midrange- 23-30mm ish.


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## Bike Whisperer (Aug 7, 2012)

clbaumer said:


> Just a thought;
> 
> This seems, to me, like it will be the same argument as 26" vs 29", but then eventually will come to an agreement that the middle is realistically the best. I haven't rode on real wide rims yet, but I have a feeling that eventually all will agree in the midrange- 23-30mm ish.


Who came to an agreement that the middle is best...best for what?
XC
SS
DH
FR
AM
Trail
Short riders
Tall riders

There is no middle and there is no best...different strokes for different folks


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## clbaumer (Oct 21, 2013)

Bike Whisperer said:


> Who came to an agreement that the middle is best...best for what?
> XC
> SS
> DH
> ...


I didnt say we had come to an agreement, i said eventually will. And there is always a middle, and always a best, at least majority wise. Basically, its will be a bell curve, just like everything.


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## Deerhill (Dec 21, 2009)

*For rocky trails..*



Yody said:


> And rock Stikes while turning, thru rocks, with a wide run unprotected because of a stretched out tire with no sidewall bulge. .. is very dangerous at speed


I do like the wide/light weight 2.4" single ply benefits and plushness at moderate speed, but I agree with this ^^. Even with pressure through the roof, the casing expands and the volume is just not progressive enough to take high speed hits w/o bottoming.. @ 35-40mm internal rim width, a single ply needs a 200g road slick installed inside.


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## Bike Whisperer (Aug 7, 2012)

clbaumer said:


> I didnt say we had come to an agreement, i said eventually will. And there is always a middle, and always a best, at least majority wise. Basically, its will be a bell curve, just like everything.


I do not believe there will ever be an agreement, there will always be three wheel sizes from this point on because different wheel sizes work better for different riders, terrain, bikes, etc. We has consensus 15 years ago, now it's gone and it's not coming back.


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## BikeBert (Mar 17, 2008)

*wider is better *

Maybe it looks like marketing BS but I find these images pretty close to what I experienced with my 35mm wide rims.

















Disclaimer: I am not a downhiller but I like riding steep and technical terrain; I call it trail riding, some call it Enduro. Also, I'm quite a heavy rider at ca. 200 lbs, hence I prefer stronger wheels, which doesn't necessarily mean heavier. My set is 1700g. 

First off, I was surprised by the low rolling resistance of the tires put on the wider rims. The tires feel more stable while cornering and climb better due to improved grip. Also, braking distances are considerably shorter. All in all, I really like the performance of the wider rims. Nevertheless, what I find beneficial, others may find redundant. It all boils down to personal preference and there is no universal solution for everybody.

Few weeks ago [when the weather wasn't that inviting] I decided to take some measurements. I installed the same tire [*Schwalbe Rock Razor 2.35*] on two different rims with *21mm *I.D. [*DT Swiss EX 5.1 D*] and *29mm* I.D. [*Syntace W35 MX*]. In both cases I inflated the tire to 2 bars [29 PSI]. This is what I found.


*Casing **width:*

















rim DT Swiss EX 5.1D [I.D. 21mm] - *55.80mm* | rim Syntace W35 MX [I.D. 29mm] - *58.40mm*

*difference: 2.6mm*

*Thread width:*

















rim DT Swiss EX 5.1D [I.D. 21mm] - *57.55mm* | rim Syntace W35 MX [I.D. 29mm] - *57.60mm*

*difference: 0.05mm* 
practically none​
*Findings: *with the rim 8mm wider, casing expanded by 2.6mm while the thread width remained virtually the same [which is mathematically correct]. Moreover, the modified profile of a tire - a more gradual arch with more of the tread facing the crown of the tire - makes the transition to the tire's edging tread seamless and is responsible for a better grip as "more" tire contacts the ground.


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## Lelandjt (Feb 22, 2008)

oldranger said:


> Thanks for your on-topic perspective Lelandjt.
> 
> OK - there is opportunity here. I built that exact budget version for my son's Demo 8. Thinking that since he weighs 90 pounds - the lighter spec could hold up for his riding. Next time I'm out riding DH I'll try his ZTR Flow EX/DT Competition wheels on my bike and see how they work. We use Hope hubs on all of our custom wheels.
> 
> Lelandjt - how much riding time do you have on the Light Bicycle DH rims? I am interested in those. I looked at those as I viable option until I decided I didn't believe the hype.


I started using them in August. I did National Champs (16th in pro) and several Winter Park races on them. During Nats I heard several rim-to-ground bottom-out impacts but nothing bone crunching that would have caused more than a small dent in normal rims. They look like new. I run 28-29psi front, 32-34psi rear. I got the 430g version as opposed to the 370g layup that is recommended more as a wide AM rim.

While Hope hubs are nice, you can drop 1/4lb with DT 240s. Bladed spokes like DT Aerolite and Sapim CX-Ray drop another 1/4lb. The Flow EX seems pretty durable but in corners it's noticeably flexier than the Light Bicycles.


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## clbaumer (Oct 21, 2013)

Bike Whisperer said:


> I do not believe there will ever be an agreement, there will always be three wheel sizes from this point on because different wheel sizes work better for different riders, terrain, bikes, etc. We has consensus 15 years ago, now it's gone and it's not coming back.


i don't disagree with you, there a reasons to ride all different sizes and there will never be just one size that is end all. What I am saying is I believe it will be a bell curve, therefore the median will be the majority. Which would make it 27.5 wheels, with 23-30mm width is what I believe will be the majority going forward.

I don't think we will see a majority of 26 x 17mm or 29 x 45mm. Make sense?


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## unrooted (Jul 31, 2007)

BikeBert said:


> Maybe it looks like marketing BS but I find these images pretty close to what I experienced with my 35mm wide rims.
> 
> 
> 
> ...


Bert,

Can you take pics of the tire profile-without the calipers in the way?

Also can you measure the difference in height of the tires? If the tire is being flattened out, then that must mean that the distance between the rim and the top of tread would decrease, right?

Also, since the argument for wider rims is lower pressures, can you do the same measurements at 20 & 25 psi?

Thanks!


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## Brian Damage (Apr 15, 2007)

*ENVE Rims... Don't believe the hype!*



oldranger said:


> There is one reputable manufacturer - Enve


Hijacking the thread I know, but hear me out. Enve rims IMHO are all hype at the price tag they get. Why haven't they pushed the industry? Because they don't have to... yet.

But I digress..

1. Carbon rims are Stiffer / unit weight. Case in point, I build a pair of LB 30mm external rims to replace a set of Flows (nearly the same dimensions). Both with King hubs, both built by the same builder. The Flow were build up burly (I was 215lbs then). Since have dropped to 185 and build the carbon wheels accordingly. The end result was still a waaaaayyy sriffer and more responsive wheel. 390g/rim vs. 530 on the flows (650B size). BOOM 280 grams of rim alone gone. And those wheels took a beating and held up as good as the Flows.

2. Since carbon is lighter, it can go places where Al rims have not been able to succeed (wider) without the massive weight penalty.

3. Light Bicycle, Nextie, and Derby are all making carbon rims in the 35-40mm range. It's only a matter of time before the big guys will take notice. And before Enve may have to drop prices.

4. Why do the pros ride narrower? Because they are paid to, and breaking an $800 rim on a practice run is no biggie, just grab another out of the support truck.

Back to the topic... What is the best DH specific rim? I'd say it's a 40mm Derby rim with a fat Minion or your prefered front tire. Maybe go down to a 35 for the rear.


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## Shredman69 (Apr 1, 2007)

mspohn said:


> This quote right here shows why you feel a difference, but you're not feeling the advantage of a wider rim. If you move to a wider rim, keeping the tire constant, you are increasing the volume of the tire. Which means you have to LOWER the PSI to compare apples to apples. To make it simple, for the same PSI, increasing volume, makes the tire "harder".
> 
> If you increase tire volume, by increasing inner rim width, you can lower pressure, which will increase your traction - with the added benefit of having a more stable tire with regards to lateral (cornering) forces because of the rounder tire cross section.
> 
> This actually should also decrease rolling resistance, on anything but a smooth surface, because the tire can conform to trail features easily with less energy lost in the tire deformation and rebounding process.


Exactly! This is what a lot of people are just not getting.


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## Lelandjt (Feb 22, 2008)

^While I'm impressed with Derby's rims he doesn't approve them for DH and they aren't available in 26". This leaves LB, Easton, and Enve as the only carbon DH rims. With Enve you pay a lot and get a very narrow profile (remember, their sponsored riders are racing DH on the wider, weaker AM rim). Eastons are also kind of narrow, expensive, have fewer spokes, and questionable hubs (and proprietary spokes and nipples?). I'm no shill for LB but I see no other options at this strength and width without tacking on 150g per rim.


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## Shredman69 (Apr 1, 2007)

I agree. I use their 33 wide AM with Hope hubs. Mine came out at 1530g for the set. I have punished them and raced on them at Fontana a few weeks ago and they have remained perfectly true. They are way stiffer, lighter, more stable, and they hold a line way better in the turns. I run between 26-28lbs with no tubes and I can push much harder in turns without rolling the tire or burping the bead. Wider is definitely better.


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## hssp (Aug 28, 2007)

Lelandjt said:


> With Enve you pay a lot and get a very narrow profile (remember, their sponsored riders are racing DH on the narrower, weaker AM rim).


The AM is actually 24mm ID vs 21mm ID on the DH...


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## Lelandjt (Feb 22, 2008)

^Typo, went back and fixed that.


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## oldranger (Apr 14, 2011)

Brian Damage said:


> The end result was still a waaaaayyy sriffer and more responsive wheel. 390g/rim vs. 530 on the flows (650B size). BOOM 280 grams of rim alone gone. And those wheels took a beating and held up as good as the Flows.


Mr. Dain Bramage, 
You mention 650b wheels. Are you commenting on your experience with DH wheels and downhill riding, or some other kind of riding?


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## SVO (May 25, 2005)

BikeBert said:


> ​




I don't DH, but I do run 35mm rims on my winter set-up. I ride the same loop from home about 50X a year in all conditions. In any hard off-camber contact, the difference is entirely notable and has everything to do with side tire overhang and deformation- just like the picture. With thin-walled XC 2.4s at below 20 PSI I run in snow, it's night and day. Tough to imagine the exact same forces are not at play with stiffer tires and higher speeds/pressures. Just much harder to repeat the exact same line/pace at DH to experience the improvement clearly.​


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## beanbag (Nov 20, 2005)

BikeBert said:


>


Can anybody explain what is this mystery force "C" that reaches across air to try to pull the other bead off the rim? :madman:


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## unrooted (Jul 31, 2007)

Beanbag, too me it looks as though force C is coming from the rim pushing into the bead/sidewall due to Force A being directed towards B, which is farther out from the rim in the narrow rim. Makes sense to me. What this tells me is that it reduces burping to have a wider rim, which in my experience isn't quite true. . .


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## SVO (May 25, 2005)

It is apparently an attempt to simplify the complex forces with the deformation of the tire into a simple geometric comparison between rim widths. The ratio of AB/BC is a lot larger in the narrower rim, if one views the force as a rigid L-shaped lever (green) with fulcrum at point B and application at point D. More lever, easier to pop the bead. Not sure how well that mechanical analogy works in reality, and I haven't read the source page, so it's a guess as to what that depicts. But modeling this stuff with FEA or such would likely be cost prohibitive. So they gave you pretty color pictures instead. Fun!


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## beanbag (Nov 20, 2005)

I was being sarcastic. There is no "mystery force C". *The only things that exerts force on the bead, are things that actually touch the bead.* That would be the tire sidewall. Another interesting fact: a sidewall can only exert a pulling force on the bead in the same direction that the sidewall pulls on the bead. So as you can see from the two diagrams, the narrow rim version actually has more force pulling the bead towards the bead hook, and not away from it.


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## meltingfeather (May 3, 2007)

beanbag said:


> Can anybody explain what is this mystery force "C" that reaches across air to try to pull the other bead off the rim? :madman:


It seems to represent the torque caused by the folding tire pulling around the bead. Although the diagram is crude, I don't see a fundamental flaw, since it is not quantitative and is trying to demonstrate a concept.
The bigger flaw is the lack or corresponding vector on the wide rim diagram.


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## oldranger (Apr 14, 2011)

I don't know the original source of those images, but I first saw them on this PinkBike Tech article: Tech Tuesday ? Wider Rims Are Better and Why Tubeless Tires Burp Air - Pinkbike

The author attempts to explain those images. Thing is, "wide" in that article is 27 mm (exterior). So those images should be considered supporting evidence for going from skinny old-school XC rims to wide rims like the Crossmax they suggest. That rim is 21mm internal.

From that article:
"Experience has shown that switching from skinny, 22-millimeter (OD) rims to 27 -millimeter (OD) width versions dramatically increases the lateral stability of a wheel and tire in corners and in technical terrain."


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## beanbag (Nov 20, 2005)

meltingfeather said:


> It seems to represent the torque caused by the folding tire pulling around the bead. Although the diagram is crude, I don't see a fundamental flaw, since it is not quantitative and is trying to demonstrate a concept.
> The bigger flaw is the lack or corresponding vector on the wide rim diagram.


Reading that article makes my head hurt and highlights Cunnigham's deep and profound misunderstanding of mechanics.

One of the correct things is that if there is a sideways force on the tire, then one bead's upwards force will increase, and the other decrease, over the initial value. The effect is larger when the rim is narrower. But so what, if you just look at the diagrams, you will see right away that the wider rim causes higher "bead-pulling-up" forces in the first place, since the sidewalls start off more vertical. Secondly, in this modern age of Stan's bead-overstretching rims and hookless rims, nobody gives a f, nor is worried, about this upwards pulling force anyway.

Next, there is nothing special about when the contact point moves over the rim's sidewall.

Thirdly, the article claims that this "magic lever C" tries to pop the bead off towards the rim center channel. One look at the diagram shows that the sidewall is still yanking the bead INTO the hook.

The way to get the bead to fall into the center channel is if the sidewall exceeds vertical. So the narrow rim system starts off with more sidewall angle preventing this, but at the same time, is floppier so flexes over more easily. Which tire will pop off first for the same side load? It's like that issue of "thin spokes make for a flexier but stronger wheel" of which you are intimately familiar LOL.


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## Deerhill (Dec 21, 2009)

Magic lever c might only apply when riding on blacktop with red and green tires


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## Miker J (Nov 4, 2003)

Watching.


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## SVO (May 25, 2005)

Yeah, knew that. You missed my sarcasm. 

What you need to understand is that as the tire is distorted laterally away from centerline, the bike/rider weight load eventually tries to roll the tire off the rim. As lateral force increases, the centerline of the weight moves laterally and if there is enough of it, ultimately, outside the rim. At that point the weight is pushing the tire up along side the rim, rather than into it, and pulling out on the far bead. Narrower rim means less distance for the tire centerline to travel and less sidewall flex to overcome to reach that point. Both factors exacerbate potential problems with squirrelly handling from lots of smaller lateral movements and larger forces that might actually unseat the tire.


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## oldranger (Apr 14, 2011)

*interesting analysis of those images...I just don't see tires deforming like that*

I'm sure these are lots of valid points analyzing how forces affect a tire casing...I imagine that is a very difficult analysis. I for one appreciate the comments in these most recent posts. But real world pictures don't seem to show gross deformation of the casing like those drawings.

The first photo below clearly depicts his front wheel drifting/slipping, and we should expect that he is putting substantial pressure on that tire. Bit I don't see anything like behavior those drawings depict. The angle of that picture is almost perfect for this discussion.

I know - those previous diagrams are just for demonstrating a concept...but I think they might be fundamentally flawed. (aka not relevant)


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## meltingfeather (May 3, 2007)

oldranger said:


> I'm sure these are lots of valid points analyzing how forces affect a tire casing...I imagine that is a very difficult analysis. I for one appreciate the comments in these most recent posts. But real world pictures don't seem to show gross deformation of the casing like those drawings.


Downhill riders typically set pressure for hits, so riding on soft terrain, especially while dragging a foot, isn't going to show much tire deformation.
If you've ever had a rim strike or snake bite or felt the tire squirm sideways, then you'd know the tires are deforming substantially.


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## Miker J (Nov 4, 2003)

I've burped plenty of tires with hard cornering.

Anecdotally, this supports the deformation-squirm theory.


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## oldranger (Apr 14, 2011)

Miker J said:


> this supports the deformation-squirm theory.


I love that. That deserves Caps.

Deformation Squirm Theory.


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## Saul Lumikko (Oct 23, 2012)

The DH rider is in a banked corner. The angle between the tire and surface isn't extreme at all. 

It might really be that wide rims in DH use are not as beneficial as in AM/FR/Enduro type riding, where pressures are lower and tires more compliant.


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## beanbag (Nov 20, 2005)

SVO said:


> As lateral force increases, the centerline of the weight moves laterally and if there is enough of it, ultimately, outside the rim. At that point the weight is pushing the tire up along side the rim, rather than into it, and pulling out on the far bead.


I already said that there is nothing special about any weights or forces or centerlines outside the edge of the rim.


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## Brian Damage (Apr 15, 2007)

oldranger said:


> .
> I know - those previous diagrams are just for demonstrating a concept...but I think they might be fundamentally flawed. (aka not relevant)


Hahaha.... Your arguments make me laugh so hard it brings a tear to my eye . Thank you!

The diagrams are meant to show the angle at failure. Your pictures do not show anything close to a failure of any width rim. I'm sure there a many more extreme images out there. Have you ever burped a tire? If not, keep using your skinny rims and keep thinking you are fast of the Dh's. But you started the debate asking the question: 'is wider better for DH'. If you haven't tried both then your opinions are just that... opinions. Let's hear from someone who has tried 'real' wide composite rims (I'm not talking about 25 v 21mm internal width) and compared them to 'narrow' rims in the 25mm range. Just sayin... Try it, you might like it.


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## oldranger (Apr 14, 2011)

Saul Lumikko said:


> It might really be that wide rims in DH use are not as beneficial as in AM/FR/Enduro type riding, where pressures are lower and tires more compliant.


This is where I'm 'at' on this subject. But, with that said, there has been one experienced DH rider/racer give specific, experience based recommendations that the LightBicycle DH rim offers a better ride for DH racing. I don't think anyone else contributing to this thread has made any specific rim/tire recommendations based on DH experience. Did I miss any?


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## Brian Damage (Apr 15, 2007)

*Is this relavent enough for you Mr Ranger?*

I like this one


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## pharmaboy (Nov 11, 2005)

Lol, that's a ripper of a photo!

Test theory - put 20 psi in front tyre, go for ride on rough concrete or bitumen path and at slow speed turn sharp.

THAT noise and nearly coming undone was tyre deformation. One of the reasons that mountain bikes aren't suitable for flying down a mountain road at 10 tenths, because you'll roll the tyre off and die. That there is no witnesses to this exact outcome only goes to prove the point! 

Now, I don't know about the rest of you, but I pretty much have never had bitumen type levels of grip offroad so the point is pretty moot - I'm more likely to burp a tyre sliding down into a rut than anything else, because grip on dirt is very rare for my riding areas.


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## oldranger (Apr 14, 2011)

Thanks. I love pictures. What kind of rim is that? Looks old. Perhaps some old school skinny Mavic rim to go with that old fork, and the even older Kenda tire not designed for tubeless. Does that fork have a standard QR axle with IS mounts for a brake? 

Can you find a picture like that from this decade?


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## oldranger (Apr 14, 2011)

*You picked a winner of a pic Mr. Bramage*

Google tire burp and within 5 seconds I find the source of your pic. This is too good.

No. It's not relevant.


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## Shredman69 (Apr 1, 2007)

oldranger said:


> Google tire burp and within 5 seconds I find the source of your pic. This is too good.
> 
> No. It's not relevant.
> 
> View attachment 875036


How is it not relevant? It's a skinny rim with the tire folding and burping under a load. Unlike your pics that show that the bike is not even under a load. Look at the suspension on the pics that you posted, it's not even compressed. Of course their is no deformation, there is no load on the tire. I have used both skinny and wide rims, both tubeless. I've folded and burped the tires on the skinny rims but I've yet to have that happen on my wide rims, even though I run less pressure in my wide rims than I did in my skinny rims. I get better traction and I can rail turns harder and faster than I ever could on my skinny rims. They are LB carbon, 33 wide external and 26 wide internal and 30 deep. It's pretty simple and an easy decision to make. Wider is better for all riding, especially DH.


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## MTBMILES (Dec 27, 2007)

old ranger will never change his mind and will always go back to " I am talking about DH", this forum already believes the hype. 


Sent from my iPhone using Tapatalk


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## Shredman69 (Apr 1, 2007)

LOL, true.


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## pharmaboy (Nov 11, 2005)

Shredman69 said:


> How is it not relevant? It's a skinny rim with the tire folding and burping under a load. Unlike your pics that show that the bike is not even under a load. Look at the suspension on the pics that you posted, it's not even compressed. Of course their is no deformation, there is no load on the tire. I have used both skinny and wide rims, both tubeless. I've folded and burped the tires on the skinny rims but I've yet to have that happen on my wide rims, even though I run less pressure in my wide rims than I did in my skinny rims. I get better traction and I can rail turns harder and faster than I ever could on my skinny rims. They are LB carbon, 33 wide external and 26 wide internal and 30 deep. It's pretty simple and an easy decision to make. Wider is better for all riding, especially DH.


Not relevant - are you seriously asking why it isn't? That picture is in the middle of a crash - he has landed withthe wheel at an angle to direction - it is not in any way a tyre losing grip in the midst of turning - look where his right knee is FFS.

It doesn't prove anything, nor disprove anything either - it is however an amusing photo.

And before you go off at me as well, if I were ordering a set of LB rims I would order wider rather than skinny, but that's on the basis that I don't see anything to lose and maybe something to gain with wider rims, and I certainly wouldn't bother with 18mm internals.

The other thing I think you are missing is that tyre and rim interface is mostly the cause of burps - if the tyre goes on super easy and is hard to inflate because it's so loose - then that's a tyre that is going to burp easily. A hard cornering friend of mine used to burp all the time - he fixed it when he changed to tyres that were tighter fit.

If you changed from identical sized rims to wider ones and used the same tyres and burping stopped, I think then you have some evidence. As soon as you change a couple of things at a time, all you have is supposition.


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## beanbag (Nov 20, 2005)

oldranger said:


> 2013 winning riders
> 
> Steve Smith - Easton Havoc 23mm
> Greg Minnaar - Enve DH 21mm (30mm external)
> Aaron Gwin - DT FR600 24.9mm


I think this is a good point. One of my rules of thumb is: "If you don't know what you are doing, follow other people that do" LOL. I would think that pro downhillers are more interested in winning, than running whatever sub-optimal stuff their sponsors give them. Like maybe if they thought wide rims were so great, then they can buy the rims themselves and peel off the labels.

But this assumes you also have the same equipment as the pros and your goal is always to go as fast as possible.

Of the few things that are true and relevant is that wider rims cause tires to feel laterally stiffer, and maybe your chance of bonking the rim is higher.

This "tire peeling off" stuff is all BS, I mean, how many pro downhillers go around peeling off their tires coz their rims were too narrow? On the other hand, maybe you suck as a rider and don't run the right pressures, in which case, tire peel could be an issue for you. Maybe the real question is:

Are you GOOD ENOUGH to run narrow rims like the pros? LOL


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## nogod (May 30, 2009)

If a flat wide profile is desired, why is it that tire manufactures seem to think that a rounded tire is what is best? The logic seems to be that wide rimes are a compensation for a poorly designed tire in order to use low pressure. perhaps a tire with a flatter profile and thicker sidewalls would make more since?

But then there may be a solution: The dual chamber tire Detail - Schwalbe Professional Bike Tires








_"With the current trend towards wide wheel rims, the trail performance of the tires at low air pressure is improved and has become less "spongy". The risk of snake bites, however, remains the same.

The solution is an innovative dual chamber system. There is an additional air chamber inside the tire. This inner chamber is filled with high air pressure and effectively prevents the tire hitting the edge of the rim. At the same time, the inner system also secures the tire on the rim and prevents the dreaded "burping", a loss of air of the tubeless system in the case of low pressure. Depending on the situation, the air pressure in the outer chamber can now be reduced to 1 bar (14psi) without running any risk."_

For the record though a tire with more pressure is less likely than a tire with lower pressure to roll over. And if your tire is hard then you can use the tread on the rounded side of the tire. meaning that if you have higher pressure you need a rounder tire profile. Generally speaking downhill bikes have higher pressure. Applied to the average rider it means if for whatever reason you need higher pressure in your tires a narrower rim is better. But if you can can or want to run lower pressure then a wider rim is in order. Or what is more fun just ride what you have and what you want.


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## shiggy (Dec 19, 1998)

nogod said:


> If a flat wide profile is desired, why is it that tire manufactures seem to think that a rounded tire is what is best? The logic seems to be that wide rimes are a compensation for a poorly designed tire in order to use low pressure. perhaps a tire with a flatter profile and thicker sidewalls would make more since?


Because two wheeled vehicles handle like crap on tires with flat treads.

*ALL* bicycle tires have round profiles. Any squaring off is relative.

IME too narrow a tire on too wide a rim is worse for handling than the other way round, and is more prone to pinch flats and sidewall damage.


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## oldranger (Apr 14, 2011)

*Yes I will, well, maybe after another year...*



MTBMILES said:


> old ranger will never change his mind and will always go back to " I am talking about DH", this forum already believes the hype.


Actually, I have been influenced by this thread, just not willing to take advice about how wide, light rims with low psi perform for Trail, AM, and Enduro and apply it to my DH bike spec. (that I race for fun, on my dime)

•	I will watch to see how the 26mm internal width LightBicycle DH rims hold up for you folks over the 2014 season. Hadn't thought about carbon - which has been out of my price range.
•	Based on contribution to this thread - I have decided that I will build up a set of DT Swiss FR600 rims with DT Comp spokes for my normal DH wheels. The FR600 width falls in to the range the Maxxis tires are said to be designed for.
•	My choice to go with FR600 is primarily based on the good balance of width, weight, the tires I intend on using, and the price. I intend on running Maxxis DHF and HR2 tires again this year. The $90/rim FR600s have a relatively wide 24.9mm internal width, a record of durability, and are used by race teams and one of the top riders, and come as OE on one of the top DH bikes available. 
•	I will put away my heavy Atom Lab Pimp2 rims with Champion spokes and save them for days at Windrock, TN. 
•	I will also give my set of 2013 Stans ZTR Flow EX wheels a try on my Demo when I'm riding DH some day. That will help gauge the benefit of light rims - and see if it might be worth the $$
•	Oh, and I'd love to ride anyone's wide rims that wants me to see the light. 

I really appreciate the time each of you has taken to share your observations, facts you've found, and opinions. It's been fun to debate, and this is a great forum for that. There have been some key contributors to this thread that I'd like to call out. These folks have offered succinct, specific suggestions based on professional experience, or a noteworthy track record of participation in MTB riding and racing:

*Bholwell, Tire Design & Development Engineer*. "_A greater difference will be felt when running thinner, AM or XC tires at lower pressures. Yes, I designed the DHR2 and the HR2 on a 23mm internal width rim, but the difference in profile going from 23mm to 28mm internal isn't much._"

*Lelandjt, DH rider with 10+ years of competition including Pro DH* - "_On my DH bike I've exclusively used the Minion DHF 2.7" since like 2004. I've tested other tires but always go back to my standard. Keep in mind that the 2.7" Minion measures the same as the 2.5"s from Spesh, Conti, Bontrager, ect. I've used them on rims from 23-30mm and prefer 26-29mm"_. Leland recommended the Light Bicycle DH rim (inner 26mm, outer 33mm). This guy has a record of going fast DH.

Also - thanks to *Beanbag*, for your well-crafted and on-topic contribution when the talk got technical.

Interesting that there hasn't been a recommendation for using wide aluminum rims like the $1,200 Industry Nine Gravity Rim (33.5mm outer/28.5mm inner width).


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## meltingfeather (May 3, 2007)

oldranger said:


> Interesting that there hasn't been a recommendation for using wide aluminum rims like the $1,200 Industry Nine Gravity Rim (33.5mm outer/28.5mm inner width).


The $1,200 Industry Nine product is an entire wheel.


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## mtnzj (Mar 13, 2009)

I9 Gravity Review
Industry Nine 26" Gravity Wheels - Reviewed - Pinkbike


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## meltingfeather (May 3, 2007)

beanbag said:


> Can anybody explain what is this mystery force "C" that reaches across air to try to pull the other bead off the rim? :madman:


Looking back at it, C looks like the moment about the bead produced by the force vector AB, which also explains why there is not a corresponding moment in the wide rim diagram... AB is through the bead, thus producing no moment about it.
Accurate? No comment... :arf:
The more I look at those diagrams the more I think they are useless.


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## beanbag (Nov 20, 2005)

meltingfeather said:


> The more I look at those diagrams the more I think they are useless.


This is a good assessment. Think about this:

Why is it that the tire is pushed over sideways, yet this mystery force AB is still exactly in the plane of the wheel? The Cunningham mystery lever is an L-shaped device that has the corner at one bead, the top at the tire contact point, and the other end trying to lift the other bead. To operate this mystery lever, you have to push SIDEWAYS at the top, not down. (Doesn't anybody know how to operate a lever these days?) Using this "explanation" (LOL), there is no special threshold point between a wide vs narrow rim.

BTW, when I did google search on pink bike wide rims, I came across this article:
To the Point: Bill Shook on Wheels and Wide Rims - Pinkbike

where American classic says they use 32mm for their XC rims, and 28mm for free-ride, because if they made their freeride rims 32mm, it would be "too heavy to ride uphill".  So by logical extension, that means that DH rims should be 24mm wide.


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## Shredman69 (Apr 1, 2007)

BTW, when I did google search on pink bike wide rims, I came across this article:
To the Point: Bill Shook on Wheels and Wide Rims - Pinkbike

where American classic says they use 32mm for their XC rims, and 28mm for free-ride, because if they made their freeride rims 32mm, it would be "too heavy to ride uphill".  So by logical extension, that means that DH rims should be 24mm wide.[/QUOTE]

Obviously a typo. 32 is the FR rim, not XC rim. The lighter narrower rim is the XC rim.


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## TedS123 (Dec 2, 2009)

The new AC Wide Lightning is 32 mm outside/ 29 mm inside width and is targeted at XC/Trail/AM. It's interesting that AC is pushing wide rims for XC.

I do mostly XC/trail riding in the rooty, rocky east, with a few races. I've been trying to decide between the LB 22 and 30 mm inside wide hookless, so this thread has been interesting. Was wondering if 30 mm might be too much for my typical 2.2 - 2.35 tires. So the Wide Lightning seems to support the thinking that wide rims are good for xc.

Sent from my XT907 using Tapatalk


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## oldranger (Apr 14, 2011)

This comment from Bill Shook is on the topic:

"_I started these riders with rim widths at 24 millimeters wide, then 26 millimeters, each with reductions in tire casing size and weight, Then I tried 28 millimeters with a subsequent reduction of tire casing size and weight. In watching this progression, I saw that the profile of the tire on the rim (as a unit) was going more and more towards a half-circle shape (hemispherical tire profile). I took it to its conclusion and the sweet spot is at 32 millimeters wide, as it is the maximum lightest casing with the best tire profile. If you go beyond that to, say, 36 millimeters wide, you get negative returns, because the shape of the tire on the rim exceeds the optimum hemispherical shape._"

There is also another watch out when reading that article and interpreting Bill's reference to 'width'. He is referring to outside width, and the rim material is thinner for XC rims. It is typical that for a DH rim, there is a difference of 6-7 mm between the inner and outer width of the rim. (Not 3mm difference like the AC Wide Lightening rim)


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## Surestick Malone (Jan 24, 2004)

oldranger said:


> This comment from Bill Shook is on the topic:
> 
> "_I started these riders with rim widths at 24 millimeters wide, then 26 millimeters, each with reductions in tire casing size and weight, Then I tried 28 millimeters with a subsequent reduction of tire casing size and weight. In watching this progression, I saw that the profile of the tire on the rim (as a unit) was going more and more towards a half-circle shape (hemispherical tire profile). I took it to its conclusion and the sweet spot is at 32 millimeters wide, as it is the maximum lightest casing with the best tire profile. If you go beyond that to, say, 36 millimeters wide, you get negative returns, because the shape of the tire on the rim exceeds the optimum hemispherical shape._"
> 
> ...


I read the article. There's no mention of why a hemispherical profile is better or what width tire the magical 32mm wide rim is best with. 
Also, why reduce tire size with increase in rim width? You'd want to try a range of tire sizes with a range of rim widths.
Not a very informative article, more of an an exercise in marketing.


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## pharmaboy (Nov 11, 2005)

The article is a bit like asking the Pope what's wrong with the Catholic Church .

It seems to me that the main driver of wider rims in xc has been American Classic, and the main opinion site has been pinkbike with similar fervour.

What the shape of the tyre is on the rim seems a little irrelevant to me unless you are running 50psi. What matters is where the rubber meets the road with an enormous flat spot at 25psi with presumably a change in the bulge depending on rim width. But that change in bulge while it might lead to an efficiency change, also means a less compliant ride over rocks.

I can't help but wonder that tyre developers would be making tyres to suit the average rim out there and to perform well in that environment. Would schwalbe be designing tyres for xc to work best with a 28mm ID rim?


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## beanbag (Nov 20, 2005)

Sissy riders like me would probably benefit from wider rims because they raise the side knobs on the tires and make them engage earlier.


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## meltingfeather (May 3, 2007)

beanbag said:


> Sissy riders like me would probably benefit from wider rims because they raise the side knobs on the tires and make them engage earlier.


Wide rims make tires square, which is cool.


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## ca_rider (Feb 3, 2008)

meltingfeather said:


> Looking back at it, C looks like the moment about the bead produced by the force vector AB, which also explains why there is not a corresponding moment in the wide rim diagram... AB is through the bead, thus producing no moment about it.
> Accurate? No comment... :arf:
> The more I look at those diagrams the more I think they are useless.


Good point, I'll add support for it.

No moment exists at C because torque cannot be transmitted through the tire sheet. Any torque would be caused by viscous shear from fluid flow within the tire, and as we all know these internal fluid forces are negligible in comparison to other forces within the tire. Also, D is wrong. As we all know, internal pressure acts along the normal to the tire surface but is neglected. D should not be upward (away from the rim seat) but outwards through the rim sidewall.

The figure is clearly drawn by somebody that does not understand mechanics. E.g. the impinging forces do not sum to the reactive forces, and how does AB cause lateral flex, since it is vertical. The figure should be discounted wholly.

In my perspective, wider rims do two things:
i) Provide a harsher cushion of air to ride on for a given pressure. The harshness of the ride will scale positively but less than linearly with the width of the rim. The logic is as follows. It is surely commonly understood that the tire area which supports the rider is the same for constant tire pressure, this follows from the definition of pressure which is approximately constant within a tire. For a wider rim, the width aspect of the support area increases and the circumferencial aspect of support area decreases. Since the circumferencial dimension is less rigid than the width dimension due to fact that tire sheet shear contributes more to balancing forces in this aspect, the ride becomes harder. These two effects allow for achieving stable conditions at lower pressure.

ii) Reduce tire roundness, which reduces handling as Shiggy mentioned. One way to rationalize this is to imagine the roundness as contributing to a varying tire height as a function of aspect angle. As the bike lays over to one side (i.e. carving), the slope of the change of radius causes the bike to turn. This slope is exactly related to the change in radius as a function of aspect angle. That is, round tires turn better. Square tires don't turn as a function of aspect angle. To lay over a bike with square tires and turn is to use the angle and centripetal forces to balance against the forced turning of the handlebars but fully neglects turn contribution from tire design.

Lastly, rolling efficiency is characterized by the sum of PV work and mg*delta(h) work whereas heating and other effects are negligible. The PV work is dominated by mg*delta(h) work since fluid redistribution allows impact energy to be stored elastically over the entire fluid volume and tire surface so local fluid pressure spikes are minimized at characteristic timescales. As such, the harsher riding wide rims will be less efficient due to more delta(h), regardless of operating pressure.

If I get a chance I'll run some simulations regarding this within the next 6 months. After reviewing the literature, I found very little published analysis on the subject.


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## oldranger (Apr 14, 2011)

ca_rider said:


> The figure should be discounted wholly.


(ca_rider) is referring to the figures from the pinkbike article "Wider Rims are Better..."

Thank you Sir. I appreciate the effort you put in to your explanation.

(Though you are bringing back bad memories of how bad I felt when I got a D in Physics because I was too busy rock climbing to go to class)


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## Guest (Mar 10, 2014)

meltingfeather said:


> Wide rims make tires square, which is cool.


imma square does it make me cool?


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## Shredman69 (Apr 1, 2007)

This is a good article on wide tires with lower pressure roll faster and are more efficient than narrow tires with higher pressures. I know it's not about the rims, but they go hand in hand.

http://www.mtbonline.co.za/downloads/Rolling_Resistance_Eng_illustrated.pdf


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## HillDancer (Dec 10, 2012)

I have wide rims, and I've used narrower rims, the ride is not harsher on the wider rim than with the same tire on a narrower rim; increased volume = increased pneumatic suspension with tire construction being constant.

Circumference of a tire is constrained by its cords, it does not vary with rim width. A narrow tire, narrow rim, or combination of both, creates a longer contact patch than the same tire on a wide rim, which increases pneumatic trail, and increases slip angle. High pneumatic trail plus wide slip angles slow steering response and encourage understeer.

Tire shape does not become square with an increase in rim width; square is just a stereotype label used to pigeon hole info. While there is much to disagree with one line with an arrow in the disputed diagram without knowing the illustrator's intent, the outside shape of the tires in the illustration are representative of rim width's effect on casing shape. The narrower rim produces a more obtuse shape surrounding the contact patch when viewed on a coronal/vertical plane. With the tire's center further from the rim's center, slip angle increases. The greater the slip angle, the further the tire lags behind steering input.


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## ca_rider (Feb 3, 2008)

There is a lot of conjecture in this thread including questionable references and philosophies, anchored with bad diagrams and articles written and illustrated by people not trained to analyze mechanical systems correctly (aka marketing departments). I'll indicate some technical refs here and hope it aids the discussion. My sincere opinion is that a reasonable understanding of the principles outlined for instance in the refs below is necessary to gauge tire and rim design correctly. I question every article linked thus far based on flawed rationale.

For reference, some captures of tire force distributions are shown below.




































The above captures are from 
http://www.nhtsa.gov/staticfiles/safercar/pdf/PneumaticTire_HS-810-561.pdf

Another good theoretical reference is
https://archive.org/download/nasa_techdoc_19700007105/19700007105.pdf


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## ca_rider (Feb 3, 2008)

Thank you for your thoughtful comments.



HillDancer said:


> the ride is not harsher on the wider rim than with the same tire on a narrower rim


Sorry, I meant for the constant pressure case.



HillDancer said:


> Circumference of a tire is constrained by its cords, it does not vary with rim width.


I fully agree for a fully inflated tire when cords are at design tension. My understanding of the intent of wide rims is to find stability at less than design pressure.


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## ca_rider (Feb 3, 2008)

HillDancer said:


> I have wide rims, and I've used narrower rims, the ride is not harsher on the wider rim than with the same tire on a narrower rim; increased volume = increased pneumatic suspension with tire construction being constant.
> 
> Circumference of a tire is constrained by its cords, it does not vary with rim width. A narrow tire, narrow rim, or combination of both, creates a longer contact patch than the same tire on a wide rim, which increases pneumatic trail, and increases slip angle. High pneumatic trail plus wide slip angles slow steering response and encourage understeer.
> 
> Tire shape does not become square with an increase in rim width; square is just a stereotype label used to pigeon hole info. While there is much to disagree with one line with an arrow in the disputed diagram without knowing the illustrator's intent, the outside shape of the tires in the illustration are representative of rim width's effect on casing shape. The narrower rim produces a more obtuse shape surrounding the contact patch when viewed on a coronal/vertical plane. With the tire's center further from the rim's center, slip angle increases. The greater the slip angle, the further the tire lags behind steering input.


I wish I read your post before posting my latest diatribe so as to include some of it. I agree with your point about steering input lag, which is captured in 2.46 and to your point about chords defining spanwise profile, and that tires do not become 'more square' at lower pressure, figure 7.38 and chapter 7 in particular pertains to the relevant mechanism and in this case discerns the difference in load distribution as a function of approach to load rating which indicates profile dominance by chords vs external forces (internal pressure vs. road).


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## meltingfeather (May 3, 2007)

HillDancer said:


> Circumference of a tire is constrained by its cords, it does not vary with rim width.


This is not true.
You have to be very careful when comparing belted radials like the "medium duty truck tires" in the NHTSA study cited above to bicycle tires.
Apples and oranges.


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## HillDancer (Dec 10, 2012)

There is a period of cord elongation and material spread between the weave during the early life of a bicycle tire, after which tire circumference stabilizes, or at least slows considerably. Cotton and Aramid fibers have varying limits, which can produce apples to oranges growth outcomes, rim width however, does not effect this change.


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## Shredman69 (Apr 1, 2007)

Truck tires on pavement and mountain bike tires ridden offroad can not be compaired. Here is your scientific test data on mountain bike tires.

http://www.mtbonline.co.za/downloads/Rolling_Resistance_Eng_illustrated.pdf


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## oldranger (Apr 14, 2011)

Shredman69 said:


> Here is your scientific test data on mountain bike tires.
> 
> http://www.mtbonline.co.za/downloads/Rolling_Resistance_Eng_illustrated.pdf


I was resisting, but since you posted the link a second time, I have a question Shredman: which of the grueling test scenarios on that 5.7% grade 460m climb test track is most like the type of riding (shredding) you do? The 'Road', the 'Gravel', or the 'Meadow' scenario?

I'm guessing the gradual uphill 'Meadow' is most like what you ride, since that is the scenario the PhD student/author/test rider suggests is most beneficial for wide (2.3 - 2.4) tires and very low tyre pressure (21psi)(with a y).


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## MTBMILES (Dec 27, 2007)

Old ranger are you saying this test isn't DH so it isn't relevant? 


Sent from my iPhone using Tapatalk


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## Shredman69 (Apr 1, 2007)

MTBMILES said:


> Old ranger are you saying this test isn't DH so it isn't relevant?
> 
> LOL, he doesn't think anything is relevant unless its on skinny rims with DH tires and high pressure.:lol:


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## ridonkulus (Sep 5, 2011)

Ok, we are all arguing over theoretical science, I'm not gonna trust any of these until we here from several sources that have actually ridden wide rims, as in 30mm+, and the narrower options out here.


Your science may very we'll be right but how it translates to real trail riding is what matters


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## Shredman69 (Apr 1, 2007)

oldranger said:


> I was resisting, but since you posted the link a second time, I have a question Shredman: which of the grueling test scenarios on that 5.7% grade 460m climb test track is most like the type of riding (shredding) you do? The 'Road', the 'Gravel', or the 'Meadow' scenario?
> 
> I'm guessing the gradual uphill 'Meadow' is most like what you ride, since that is the scenario the PhD student/author/test rider suggests is most beneficial for wide (2.3 - 2.4) tires and very low tyre pressure (21psi)(with a y).


LOL yep mostly open meadows. Here I am on some of them. You can see the tire and rim in action. It's a 2.35 Nevagal on the 26mm int 33mm ext carbon rim tubeless with about 25 psi in the front.

Rock-It trail in Aliso Woods on my 2013 Intense Uzzi. - YouTube

1st time down Car Wreck in Aliso Woods - YouTube

Oh yea, and I got 4th on my last "open meadow" DH race too.


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## Deerhill (Dec 21, 2009)

Thought op was referring to 30-40mm internal rims, no?


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## oldranger (Apr 14, 2011)

MTBMILES said:


> Old ranger are you saying this test isn't DH so it isn't relevant?


No.

I've accepted the fact many of the contributors on here want this thread to be about trail (All Mountain, XC, etc.) tires and rims. I'm disappointed about that, but there has still been some good, on topic contribution, I just have to be willing to disregard all the noise.

That article and the premise of the test is kind of silly. Did you read it? The word 'rim' doesn't show up in the article at all until the last paragraph when the author mentions that is is a factor when setting tyres up.


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## kiloman (Feb 14, 2012)

Shredman69 said:


> LOL, he doesn't think anything is relevant unless its on skinny rims with DH tires and high pressure.:lol:


LOL, you guys are still at it, trying to convince _oldranger_? Haven't you figured out yet that he doesn't want to be convinced? He's just instigating you into continuing to make replies.


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## meltingfeather (May 3, 2007)

HillDancer said:


> Circumference of a tire is constrained by its cords, it does not vary with rim width.


See this thread where former Maxxis tire development engineer bholwell said this (among many other things):



bholwell said:


> Ok. Nylon fabric is elastic in the direction of the threads, and has almost no strength in the direction perpendicular to the threads. This is why two plies are needed at opposing angles (all mountain bike tires are of bias construction).
> 
> Yes the hoop tension at the outermost circumference of the tire will increase as the tire O.D. attempts to increase, and will restrict it to some degree. In my first graph, the section height changes, what, 1mm when going from a 17mm rim to a 27mm rim? Or less than a 3mm change MAX? I would venture to guess that in practice, the section height would change 80-90% of the theoretical.


Rim width does affect casing height (and therefore tire circumference).


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## HillDancer (Dec 10, 2012)

I concede, it is possible there is a minor change in height.


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## oldranger (Apr 14, 2011)

kiloman said:


> LOL, you guys are still at it, trying to convince _oldranger_? Haven't you figured out yet that he doesn't want to be convinced? He's just instigating you into continuing to make replies.


Alright kiloman, here is what would convince me that a rim with >25mm internal width could be an optimal choice for a Downhill (DH) rider:

1) Information that any tire manufacturer is specifically designing a 2-ply DH tire for a rim with an internal width of any single value >25mm. This would be especially convincing.
2) Information that any one of the top 10 UCI DH Race teams is using a rim with an internal width >25mm. This would show support for theory in practice.
3) Information that any of the top 10 bike manufacturers are spec'ing a top-of-the-line DH bike with a rim that has an internal width >25mm. This would support the market backs opinion with $$
4) The opportunity to ride a set of Industry Nine Gravity wheels for a weekend. This would give me an opportunity to form my own opinions objectively without being confronted with the all-to-common propensity to justify a mod you just spent $$ on.

Frankly, the I9 wheels are so cool, I was hoping someone on this forum would help me with some data that would justify the purchase. No such luck.


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## meltingfeather (May 3, 2007)

oldranger said:


> I'm guessing the gradual uphill 'Meadow' is most like what you ride,





Shredman69 said:


> Here I am on some of them.


lol pwnt


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## Shredman69 (Apr 1, 2007)

IKR!!! :lol:


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## oldranger (Apr 14, 2011)

OK. Shredman - you should feel good about your accomplishments on those trails, and your race result. It looks like you've got your bike setup just right for that kind of riding.

What kind of rims are those?


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## beanbag (Nov 20, 2005)

oldranger said:


> Frankly, the I9 wheels are so cool, I was hoping someone on this forum would help me with some data that would justify the purchase.


Like what kind of "data" are you looking for?


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## Shredman69 (Apr 1, 2007)

oldranger said:


> OK. Shredman - you should feel good about your accomplishments on those trails, and your race result. It looks like you've got your bike setup just right for that kind of riding.
> 
> What kind of rims are those?


Thanks Ranger. Those are Light Bikes Carbon AM rims. The same ones that lelandjt has, except his are the slightly heavier DH version. Same dimensions though, 33mm ex, 26mm int and 30mm deep. The AM ones are advertised at 370g each, but mine weighed 350 and 360. The 350 is on the front and the 360 on the back. With Hope Pro2 EVO's and DT super comps and alloy nips they came in at 1520g for the set. They're light, stiff, strong, fast and WIDE.


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## oldranger (Apr 14, 2011)

beanbag said:


> Like what kind of "data" are you looking for?


I dunno, maybe "data" is the wrong word. Perhaps just some theoretical model that passed muster on this forum, or quantitative observations from a consistent athlete (like "my times over xx runs were consistently xx seconds faster"). Or maybe someone credible like bholwell would have said something like "I designed the HR2 or DHF on a 27mm rim" (which he didn't, he indicated it was a 23mm width).

The debate was fun, though.


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## beanbag (Nov 20, 2005)

oldranger said:


> I dunno, maybe "data" is the wrong word. Perhaps just some theoretical model that passed muster on this forum,


I once had a theorist tell me, "Don't worry about your data. I can create a model where your results are the correct ones."



> or quantitative observations from a consistent athlete (like "my times over xx runs were consistently xx seconds faster").


You already have this info from the rims that the winning pros use.



> Or maybe someone credible like bholwell would have said something like "I designed the HR2 or DHF on a 27mm rim" (which he didn't, he indicated it was a 23mm width).


Probably what he meant was the "roundness" of the profile e.g. how soon the side knobs start to engage. I would think that depends on your riding style. Maybe the "pros" lean their bikes over more and want the side knobs to engage later, hence the narrow rims.


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## Deerhill (Dec 21, 2009)

oldranger said:


> I dunno, maybe "data" is the wrong word. Perhaps just some theoretical model that passed muster on this forum, or quantitative observations from a consistent athlete (like "my times over xx runs were consistently xx seconds faster"). Or maybe someone credible like bholwell would have said something like "I designed the HR2 or DHF on a 27mm rim" (which he didn't, he indicated it was a 23mm width).
> 
> The debate was fun, though.


As more and more people start using these 30mm+ high volume/wide carbon rims.. the low pressure/handling feels too good.. only a matter of time till the carbon crunched on rocks photo's will start popping up


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## dirtrider76 (Sep 19, 2012)

I have been on wide rims for awhile now. 32mm and 35mm alloys with no dinged wheels.


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## Brian Damage (Apr 15, 2007)

*ENVE & IBIS both jumping on the wider is better bandwagon?*

Some interesting developments / new products in the past weeks that pertain to this debate:

Ibis released new wide carbon rims. 41 outer / 35 inner. Yes, these aren't DH specific or 26", but this is a bike manufacturer endorsing the wider is better theme.

Enve just released a new line of rims that are wider than their previous offerings.
M70 26" = 32 outer / 25 inner (intended for 70% DH)
M90 26" = 34 outer / 25 inner (intended for 90% DH)

Older Enve 26 DH are 30 out / 21 inner?

The trend is IMO pushing for wider accross the board. Where is the optimum for each category of riding? I think in the next few years the market will dictate as more major manufacturers get onboard.


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## jazzanova (Jun 1, 2008)

Just to make it whole. 
ENVE AM are 30 outer / 24 inner.


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## Brian Damage (Apr 15, 2007)

jazzanova said:


> Just to make it whole.
> ENVE AM are 30 outer / 24 inner.


Yes. I was referring to the ENVE DH rim:
http://enve.com/products/wheels/26-dh-26dh/
Since ranger doesn't think it applies if it's not DH.

Doesn't specifically callout the inner width (just the 30 outer), but on pinkbike they talked about it being 21?? not sure of the exact dimensions. But if this is correct, Enve put the extra material on the outside to provide DH strength (over the AM version) this time around instead of the inside so as to maintain the same inner width. Further evidence of the wider theme?


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## Shredman69 (Apr 1, 2007)

Envy has new rims this year, the M series. The AM rim is 32 wide 24 inside and the DH rim is 34 outside and 24 inside.

Hot Product: ENVE launches new MSERIES rims, wheelsets | Mountain Bike Review


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## oldranger (Apr 14, 2011)

So...Enve goes bigger on their DH carbon rim, but not bigger than 25mm internal...seems yet another data point that supports the position it doesn't make sense to go wider than that.


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## MTBMILES (Dec 27, 2007)

oldranger said:


> So...Enve goes bigger on their DH carbon rim, but not bigger than 25mm internal...seems yet another data point that supports the position it doesn't make sense to go wider than that.


You're too funny!

Sent from my iPhone using Tapatalk


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## ticketchecker (Mar 18, 2010)

nvphatty said:


> no thats not close to fat biking, 3.8 begins fatness. When i build my next full squish AM bike it'll use 35mm blunts with the 26" 2.75 dirt wizards which will equate to 27.5 circumference wise.


Kinda where I'm thinking. 27.5 frame with 26+ wheelset


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## slowride454 (Jan 11, 2014)

I loved when I switched to 23mm rims....on my road bike. Lower pressures and lots more comfort with 25c tires. I love my P35s and 29x2.4s and will be looking into a 40-50mm wide rim for my next wheel build. I run 25f/28r with tubes, ZERO pinch flats and lots of traction.


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## ENSANE (Nov 14, 2014)

Deerhill said:


> I find rims over @23-25mm internal width start to take a heck of a lot more hits on rocky trails (from the volume and also dings to the finish)


That's the main concern for me going wide carbon, one rock could kill a rim. Plus I've seen these internal 35mm at the shop mounted up with 2.4 minions on them, and they don't look right at all. The tires look like they could use an extra tread line on the left and right side of the tire.


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## Shredman69 (Apr 1, 2007)

Originally Posted by Deerhill 
I find rims over @23-25mm internal width start to take a heck of a lot more hits on rocky trails (from the volume and also dings to the finish)



ENSANE said:


> That's the main concern for me going wide carbon, one rock could kill a rim. Plus I've seen these internal 35mm at the shop mounted up with 2.4 minions on them, and they don't look right at all. The tires look like they could use an extra tread line on the left and right side of the tire.


You both couldn't be any more wrong. You don't "take more hits on rocky trails" because you have more volume. It's just the opposite. Because there is more volume with a wide rim, there is more cushion. And because there is more volume, you can run lower pressures and have a larger contact patch with more traction for turning, braking and acceleration. Also, tires don't roll or burp in hard corners on a wide rim like they do on a skinny rim. And if your talking about rocks hitting the sidewalls of the rim, that's a non issue. I've had plenty hit the side wall of my carbon rims with no issues. Once you try wide carbon rims, you'll. never go back. They are that good.


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## ENSANE (Nov 14, 2014)

You talking 30mm internal with or 35mm?


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## Shredman69 (Apr 1, 2007)

ENSANE said:


> You talking 30mm internal with or 35mm?


I have 2 pair of LB 33mm wide and 1 pair of LB 38mm wide carbon wheelsets. The 33's are 27 internal and the 38's are 32mm internal. I'm running a 2.5 front and a 2.35 rear on the 33's and 2.5's front and rear on the 38's and the tire profile is perfect on both. If you use too small of a tire then the profile can get a little flat, but running a small tire on a wide rim defeats the purpose of having high volume lower pressures wheels. Larger tires and lower pressures roll over rough terrain more efficiently and provide more traction in all conditions.


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## ENSANE (Nov 14, 2014)

2.4 inch wide tires have a width of 61mm. So if you ran them on a 40-41mm external rim you would have about 10mm on each side outside the rim wall....

I'd run that set up! But I like it better with a 2.5 inch tire

However if you try to run a 2.3 inch tire that is 58.42mm wide on a 40-41mm external width rim - I see some issue like having only 5mm of rubber outside the rim wall. Another issue is none of the tire manufacturers make tires to go on these width rims (most are designed around a 23mm internal width) so your contact patch is wider when the bike is perpendicular to the ground but once you enter a flat corner you actually going to have less of a contact patch because it's sooooo squared off.

So can wide rim get tooooo wide. In my opinion yes, because the rims and tires have to be made for one another. Kinda like pees and carrots. ;-)


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## ENSANE (Nov 14, 2014)

Sound like great set ups!
The bike I was referring to at the shop had 2.3 inch Maxxis Minions on the new 41mm ibis rims. Looked like a low rider Impala with the wrong size tires on it.
From the ibis website you can set up the HD3 with up to 2.4 tires. Fyi that should be the minimum if you going to run 41mm external width rims


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## dirtrider76 (Sep 19, 2012)

ENSANE said:


> Sound like great set ups!
> The bike I was referring to at the shop had 2.3 inch Maxxis Minions on the new 41mm ibis rims. Looked like a low rider Impala with the wrong size tires on it.
> From the ibis website you can set up the HD3 with up to 2.4 tires. Fyi that should be the minimum if you going to run 41mm external width rims


Maxxis seem to always run narrow. I run a 2.4Nobby Nic front and a 2.3 Spec Clutch in back on blunt35's(35outside 30inside) with no issue's at all. I have a 2.5 Minion DHF here its the same size as the 2.3 Clutch if not smaller.


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## Mountain Cycle Shawn (Jan 19, 2004)

All I can tell you is, I rode a Butcher with 40mm Derby rims. It felt like I was ridding my dirt bike, in the way I could lean on the tires and the stability they give you, even when not leaning on them. It's pretty amazing. Wait till someone starts making tires specifically for these wide rims. Then your going to see something out of this world. I've heard a couple people say that these wide rims are game changers. They are absolutely right. But, as with any big change, it will take time to work itself out and be accepted, just like disc brakes were.


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## TigWorld (Feb 8, 2010)

ENSANE said:


> So can wide rim get tooooo wide. In my opinion yes, because the rims and tires have to be made for one another. Kinda like pees and carrots. ;-)


I coudn't agree more.



Mountain Cycle Shawn said:


> ...Wait till someone starts making tires specifically for these wide rims...


This is what we need.

My Syntace W35 wheels squared off my 2.4" conti's too much, resulting in a loss of traction on corner entry compared to running them on narrower rims. You could really feel them come up on the corner knobs as you tipped it in and on hardpack with loose gravel over the top this was not ideal.


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## Shredman69 (Apr 1, 2007)

TigWorld said:


> I coudn't agree more.
> 
> This is what we need.
> 
> My Syntace W35 wheels squared off my 2.4" conti's too much, resulting in a loss of traction on corner entry compared to running them on narrower rims. You could really feel them come up on the corner knobs as you tipped it in and on hardpack with loose gravel over the top this was not ideal.


What pressures were u running? The cool thing when u run big tires with lower pressures on wide rims is the tire conforms to the trail. But if u r running to high pressures then they won't conform to the trail and they will wash out. I'm running 20-22 up front and 25-28 in the rear and I get awesome traction when railing turns.


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## Mountain Cycle Shawn (Jan 19, 2004)

TigWorld said:


> I coudn't agree more.
> 
> This is what we need.
> 
> My Syntace W35 wheels squared off my 2.4" conti's too much, resulting in a loss of traction on corner entry compared to running them on narrower rims. You could really feel them come up on the corner knobs as you tipped it in and on hardpack with loose gravel over the top this was not ideal.


I don't know what the Butcher had for tires. I plan on going back to WTB Mutano Race tires in 2.4". They're getting a little outdated, but I've always liked them. I think they'll work good with wide rims and they are easy to setup tubeless.


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## Salespunk (Sep 15, 2005)

ENSANE said:


> Sound like great set ups!
> The bike I was referring to at the shop had 2.3 inch Maxxis Minions on the new 41mm ibis rims. Looked like a low rider Impala with the wrong size tires on it.
> From the ibis website you can set up the HD3 with up to 2.4 tires. Fyi that should be the minimum if you going to run 41mm external width rims


Have you actually ridden wide rims with smaller tires? I regularly run 2.25 tires on the rear of my bike without issue on Derby 40 mm wide rims. Several of my friends to as well and again, no issues.


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## Deerhill (Dec 21, 2009)

Shredman69 said:


> You both couldn't be any more wrong. You don't "take more hits on rocky trails" because you have more volume. It's just the opposite. Because there is more volume with a wide rim, there is more cushion. And because there is more volume, you can run lower pressures and have a larger contact patch with more traction for turning, braking and acceleration. Also, tires don't roll or burp in hard corners on a wide rim like they do on a skinny rim. And if your talking about rocks hitting the sidewalls of the rim, that's a non issue. I've had plenty hit the side wall of my carbon rims with no issues. Once you try wide carbon rims, you'll. never go back. They are that good.


Bet stiffness feels good but they're expensive, I never tried wide carbon just aluminum. I like more cushion but ANY rim will get smashed if you run too low pressure..are you saying you haven't smashed up a rim yet? And yes the finish on my wider rims were more dinged up compared to rims under @ 25mm. I'm not saying it would kill a thin rim but it is a pretty damn loud hit when a good sized rock kicks up.



TigWorld said:


> I coudn't agree more.
> 
> Originally Posted by ENSANE View Post
> So can wide rim get tooooo wide. In my opinion yes, because the rims and tires have to be made for one another. Kinda like pees and carrots. ;-)
> ...


Interesting, I also notice some side knobs stick out more and some more squared off, it totally affects when they start to bite


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## TigWorld (Feb 8, 2010)

Shredman69 said:


> What pressures were u running?


I normally run 20-22 on the front with 21mm inner width rims. On the W35's I could only go 2psi lower before squirm was a major problem. So adding 7mm in rim width really only gave me a 2psi drop.

Note: Even though I use a Schwalbe digital pressure gauge, I can't say how accurate it is in absolute terms, so my 20 psi might be your 25 psi etc. What I do know from always using the same pressure gauge is what the relative differences in pressures are as I experiment with tyre setups.


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## Cayenne_Pepa (Dec 18, 2007)

I ran 23mm internal wheels. Yes, they were a bit heavy but rolled just fine. However, I went back to 19mm internal wheels, weighing almost a full pound less....and I couldn't be happier.


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## pharmaboy (Nov 11, 2005)

Shredman69 said:


> Originally Posted by Deerhill
> I find rims over @23-25mm internal width start to take a heck of a lot more hits on rocky trails (from the volume and also dings to the finish)
> 
> You both couldn't be any more wrong. You don't "take more hits on rocky trails" because you have more volume. It's just the opposite. Because there is more volume with a wide rim, there is more cushion. And because there is more volume, you can run lower pressures and have a larger contact patch with more traction for turning, braking and acceleration. Also, tires don't roll or burp in hard corners on a wide rim like they do on a skinny rim. And if your talking about rocks hitting the sidewalls of the rim, that's a non issue. I've had plenty hit the side wall of my carbon rims with no issues. Once you try wide carbon rims, you'll. never go back. They are that good.


Hi, sorry to be the correction nazi, but there is no difference in volume, period. Volume is a question of psi, tyre size and tyre elasticity. There is a difference in the shape of the tyre.

Think of this logically while picturing the tyre mounted in cross section. It is quite acceptable to say the tyre should burp less because more force at the bead is going out wards towards the rim and less outwards.

You can see the differing shapes in above posts, and certainly a wider rim causes a flatter less tall tyre. It is completely logical that this then provides less distance from the outside of the tyre (top centre) to the rim, making it entirely conceivable that you would indeed get more rock strikes on the rim if running the same pressure - but by no means certain.

If you change the shape of a tyre with rim width you will alter the way that tyre reacts to various forces. There is no free lunch, so advantages will be balanced by disadvantages - in this case wider must mean less tall.

More importantly, most posts on this thread talk about lack of squirm allowing the use of a couple of psi less - this will lead to more likely rock strikes - you simply can't avoid the physics of that without changing the tyre size


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## Mountain Cycle Shawn (Jan 19, 2004)

Deerhill said:


> Bet stiffness feels good but they're expensive, I never tried wide carbon just aluminum. I like more cushion but ANY rim will get smashed if you run too low pressure..are you saying you haven't smashed up a rim yet? And yes the finish on my wider rims were more dinged up compared to rims under @ 25mm. I'm not saying it would kill a thin rim but it is a pretty damn loud hit when a good sized rock kicks up.
> 
> Interesting, I also notice some side knobs stick out more and some more squared off, it totally affects when they start to bite


I know that Derby has sold over 1,000 rims. As of not long ago, I know there has not been a single rim failure.


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## Salespunk (Sep 15, 2005)

My rims are very scarred up but rock solid. I have run the light weight rim in the rear for over a year and have been very pleased.


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## Deerhill (Dec 21, 2009)

Mountain Cycle Shawn said:


> I know that Derby has sold over 1,000 rims. As of not long ago, I know there has not been a single rim failure.


Are those 26" rims? sounds like a job well done on those derby rims


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## Mountain Cycle Shawn (Jan 19, 2004)

Deerhill said:


> Are those 26" rims? sounds like a job well done on those derby rims


He sells all three sizes. Mostly the 29" and 27.5".


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## Shredman69 (Apr 1, 2007)

pharmaboy said:


> Hi, sorry to be the correction nazi, but there is no difference in volume, period. Volume is a question of psi, tyre size and tyre elasticity. There is a difference in the shape of the tyre.
> 
> Think of this logically while picturing the tyre mounted in cross section. It is quite acceptable to say the tyre should burp less because more force at the bead is going out wards towards the rim and less outwards.
> 
> ...


Wow, where do I even begin? U need to go back to the lab bro, u have no idea what u r talking about. And judging from your comments, u have also never ridden wide carbon rims. There IS more volume with a wide rim because it allows the tire to open up wider at the beads thus the tire and rim holds a larger volume of air. The tire IS taller with a wider rim because the tire sidewall is more straight up and down, (which also leads to more sidewall support and less squirming) compaired to a skinny rim which is more angled from the side of the tread to the bead, (also leading to squirming and burps). It's simple math man, draw a 2"angled line and a 2" straight verticle line and make the bottom of both start from the same point. Surprise! the straight verticle line IS taller. Both larger air volume and a better supported side wall means u can run less air pressure for more traction and less rock strikes, not more. I've ridden both for many years and my butt confirms all of this to be true.:rant:


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## Shredman69 (Apr 1, 2007)

Zachariah said:


> I ran 23mm internal wheels. Yes, they were a bit heavy but rolled just fine. However, I went back to 19mm internal wheels, weighing almost a full pound less....and I couldn't be happier.


Neither of those are wide.


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## Mountain Cycle Shawn (Jan 19, 2004)

Shredman69 said:


> Wow, where do I even begin? U need to go back to the lab bro, u have no idea what u r talking about. And judging from your comments, u have also never ridden wide carbon rims. There IS more volume with a wide rim because it allows the tire to open up wider at the beads thus the tire and rim holds a larger volume of air. The tire IS taller with a wider rim because the tire sidewall is more straight up and down, (which also leads to more sidewall support and less squirming) compaired to a skinny rim which is more angled from the side of the tread to the bead, (also leading to squirming and burps). It's simple math man, draw a 2"angled line and a 2" straight verticle line and make the bottom of both start from the same point. Surprise! the straight verticle line IS taller. Both larger air volume and a better supported side wall means u can run less air pressure for more traction and less rock strikes, not more. I've ridden both for many years and my butt confirms all of this to be true.:rant:


Straight from the horses ass, you might say.


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## TedS123 (Dec 2, 2009)

Shredman69 said:


> Wow, where do I even begin? U need to go back to the lab bro, u have no idea what u r talking about. And judging from your comments, u have also never ridden wide carbon rims. There IS more volume with a wide rim because it allows the tire to open up wider at the beads thus the tire and rim holds a larger volume of air. The tire IS taller with a wider rim because the tire sidewall is more straight up and down, (which also leads to more sidewall support and less squirming) compaired to a skinny rim which is more angled from the side of the tread to the bead, (also leading to squirming and burps). It's simple math man, draw a 2"angled line and a 2" straight verticle line and make the bottom of both start from the same point. Surprise! the straight verticle line IS taller. Both larger air volume and a better supported side wall means u can run less air pressure for more traction and less rock strikes, not more. I've ridden both for many years and my butt confirms all of this to be true.:rant:


A useful mathematical comparison would be to consider the tire casing as an arc enclosing different portions of a circle depending on the rim width. An infinitesimal width would have the tire enclosing the complete 360 degrees of a circle. At the other extreme, consider a wide rim that spreads the tire out to form a half-circle (180 degrees). With the same arc-length (perimeter), the area of the semi-circle is twice that of the circle (it takes just a couple minutes to work out the math to prove this). The relationship isn't linear, and if you continue increasing rim width past the perfect semi-circle the area starts going back down. But generally within the range of normal tire/ rim combinations, a wider rim should add volume to a tire.

Sent from my VS980 4G using Tapatalk


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## ENSANE (Nov 14, 2014)

Mountain Cycle Shawn said:


> All I can tell you is, I rode a Butcher with 40mm Derby rims. It felt like I was ridding my dirt bike, in the way I could lean on the tires and the stability they give you, even when not leaning on them. It's pretty amazing. Wait till someone starts making tires specifically for these wide rims. Then your going to see something out of this world. I've heard a couple people say that these wide rims are game changers. They are absolutely right. But, as with any big change, it will take time to work itself out and be accepted, just like disc brakes were.


Please post a picture of this set up. 2.25 tires = 57mm on 40mm derbys. I'm trying to decide if my next wheel build should be 30internal 35 external or the 35mm internal 40mm external.

I have not rode either, but I don't want to build a set and be disappointed. Anything is going to be an improvement on my current narrow rims, however what we are really getting at is have the rims gotten too wide >30mm internal for the current tire designs if you go with the 40mm



dirtrider76 said:


> Maxxis seem to always run narrow. I run a 2.4Nobby Nic front and a 2.3 Spec Clutch in back on blunt35's(35outside 30inside) with no issue's at all. I have a 2.5 Minion DHF here its the same size as the 2.3 Clutch if not smaller.





TigWorld said:


> I coudn't agree more.
> 
> This is what we need.
> 
> My Syntace W35 wheels squared off my 2.4" conti's too much, resulting in a loss of traction on corner entry compared to running them on narrower rims. You could really feel them come up on the corner knobs as you tipped it in and on hardpack with loose gravel over the top this was not ideal.





Salespunk said:


> Have you actually ridden wide rims with smaller tires? I regularly run 2.25 tires on the rear of my bike without issue on Derby 40 mm wide rims. Several of my friends to as well and again, no issues.


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## Shredman69 (Apr 1, 2007)

Mountain Cycle Shawn said:


> Straight from the horses ass, you might say.


Exactly!:ciappa:


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## Mountain Cycle Shawn (Jan 19, 2004)

Maybe some questions could be answered by reading this. Click on the, "read more" links.
Home, wide rims, carbon fiber rims, mountain bike rims


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## pharmaboy (Nov 11, 2005)

TedS123 said:


> A useful mathematical comparison would be to consider the tire casing as an arc enclosing different portions of a circle depending on the rim width. An infinitesimal width would have the tire enclosing the complete 360 degrees of a circle. At the other extreme, consider a wide rim that spreads the tire out to form a half-circle (180 degrees). With the same arc-length (perimeter), the area of the semi-circle is twice that of the circle (it takes just a couple minutes to work out the math to prove this). The relationship isn't linear, and if you continue increasing rim width past the perfect semi-circle the area starts going back down. But generally within the range of normal tire/ rim combinations, a wider rim should add volume to a tire.
> 
> Sent from my VS980 4G using Tapatalk


So you are saying, effectively that the wider rim changes total perimeter - hadn't treacly thought of it like that - shouldn't have said it so absolutely, sometimes it takes that though to get through to someone who thinks anecdote is evidence 

Would 5mm make as much as 2% difference? I'd like to see some accurate maths, I'd be truly stunned if there was more difference than simply going up one tyre size - say from 2.2 to 2.4.

Still everything points to shape change as the driver of advantage for using lower pressure. To lower pressure by 2psi from 20psi, is going to require something like a 20% change in volume for rim strike force to be equivalent.

Lower the pressure, increase rim strike risk unless you get a similar percentage of volume increase, fair?


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## TedS123 (Dec 2, 2009)

pharmaboy said:


> So you are saying, effectively that the wider rim changes total perimeter


Actually, no, I'm saying perimeter (tire casing) is constant (independent of rim width). But wrapping the same perimeter (arc length) 360 degrees into a circle gives half the area of wrapping it 180 degrees into a half- circle.

Sent from my VS980 4G using Tapatalk


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## jeffreyjhsu (Jun 22, 2004)

I'm jumping into this argument late but.. I'm a x-country rider weighing about 165 lbs. I've been riding my 29r American Classic Wide Lightning wheels for almost a year now. Much more traction everywhere, better cornering, smoother ride AND I can run 5lbs less tire pressure. 19mm inner rim diameter to 29.5 makes a HUGE difference.


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## beanbag (Nov 20, 2005)

http://forums.mtbr.com/wheels-tires/tire-height-vs-rim-width-756818.html


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## pharmaboy (Nov 11, 2005)

beanbag said:


> http://forums.mtbr.com/wheels-tires/tire-height-vs-rim-width-756818.html


Thx for that - keen to learn a little so read the whole lot plus a few links. By and large on volume I was wrong - volume changes by around 10% with a width change of 24 to 36 as a a example ( a bigger change than I was thinking really - I'm more an arch versus flow kind of person)

I must say though, is the conclusions of wide rims in use I stand by. The poster Hollwell, who is/was a tyre design engineer puts the case here,

how do wide rims change contact patch/effective height & width? &what tire pressure?- Mtbr.com

Which given the anecdotal discussion here, the relevant bit is probably

"_As the internal width of the rim increases, the contact patch will become wider and shorter (assuming the inflation pressure and load is kept constant.) However if the shoulder lugs are already in contact with the ground, the contact patch cannot grow wider; instead it becomes more squared off, and the pressure distribution within the contact patch changes._

_A wider rim will not allow one to run tires at lower inflation pressures without suffering rim strikes / pinch flats. To the contrary, the larger internal volume of the tire afforded by the wider rim causes the vertical deflection (i.e. suspension behavior) of the tire to become more linear. Just like a large can air shock, at the same pressure one will be more likely to bottom out the tire, all other things remaining equal.

A wider rim will, however, reduce sidewall 'squirm' at lowered pressures. Similar to someone shoving you in the shoulder with your feet spaced widely apart versus your feet closely together, the tire is better supported."_

If you burp but don't rim strike, get wider rims and use the same pressure. If you don't burp or suffer squirm problems and occasionally rim strike, wide rims won't help you.


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## Mac_Aravan (Nov 22, 2012)

Tire deflection cannot be compared to air shock has it's a totally different behavior: air shock are mainly progressive suspension (pressure increase with travel), where tire deflection is constant pressure as volume variation is negligible.

Basically a tire resist to deflection by increasing the surface patch. Once the surface patch cannot grow longer, it collapse as the force becomes a constant (pressure x surface).

That's why you can have pretty big dent even by using high volume tires: on a small surface object (rock), the patch surface cannot grow much, so you hit the rim.


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## meltingfeather (May 3, 2007)

Mac_Aravan said:


> Tire deflection cannot be compared to air shock has it's a totally different behavior: air shock are mainly progressive suspension (pressure increase with travel), where tire deflection is constant pressure as volume variation is negligible.


"Large can" and "linear" in his post made the same point you're trying to make while saying he was wrong. Large = increased volume = linear response = not progressive. :idea:


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## CuddlyToast (Oct 30, 2013)

Just to make sure everything is on the up and up,

Aaron Gwin does not run fr600 rims, he runs the enduro EX471 rims, which have a wide internal width.

Mitch Ropelato also runs the widest carbon roval rims on his enduro 29er, which he has used extensively on WC DH courses. 

Like others have stated, the Syndicate run wider AM rims, instead of the "DH" specific rims.

Norco international ran the Industry 9 gravity wheel set last year...

Believe the hype.


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## aerius (Nov 20, 2010)

DT EX471 is a 25-26mm internal rim given that it's spec'd at a 30mm outer width
Enve AM rims are 24mm
Industry 9 are 28.5mm

I can't find the specs on the Carbon Rovals, but 24mm-28.5mm isn't exactly what's hyped as wide these days. It's not XC skinny, but it's nowhere close to the 35mm & wider rims that are getting all the hype these days.


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## HillDancer (Dec 10, 2012)

Here's what Specialized reportedly said about wide recently New Specialized Roval Traverse Fattie All Mountain Wheels Show Fat?s Where It?s At

I interpret the following statement to mean the gains beyond 30mm inner width were still measurable, just not the same rising rate of significance. "From the original 22m ID of the Roval rims to the 30mm ID of these Fatties, the improvement in traction is massive, but Specialized found anything wider offered only diminishing returns."


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## Thelonerider (Sep 24, 2010)

I've always founds tire sizing for bicycle tires (road or mountain) to be purely a "guesstimate." You put the same "size" tire on two diff width rims, it will be either shorter and wider, or narrower and taller, etc. In other words the tire "size" is theoretical.

With rims width I've found the main thing is with a wider rim, the tire sits lower (so you get less cushioning from air volume between the outside and the rim when you hit a bump) but it also sits wider, so your tire surface contacting the ground is (a little) wider.

However given the difference is measured in millimeters how much difference does it make?

I would assume narrower wheels would be faster and wider would offer slightly wider contact patch with the ground. Also wider rims might be more durable and less prone to go out of true. But for most riders who don't race and are just recreational riders or just riding around, the benefit would be with narrower rims, which would likely be lighter, have less rotating mass, and be easier to accelerate or ride uphill or over obstacles like rocks and roots.


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## Cayenne_Pepa (Dec 18, 2007)

Thelonerider said:


> I've always founds tire sizing for bicycle tires (road or mountain) to be purely a "guesstimate." You put the same "size" tire on two diff width rims, it will be either shorter and wider, or narrower and taller, etc. In other words the tire "size" is theoretical.
> 
> With rims width I've found the main thing is with a wider rim, the tire sits lower (so you get less cushioning from air volume between the outside and the rim when you hit a bump) but it also sits wider, so your tire surface contacting the ground is (a little) wider.
> 
> ...


Good answer. Winner.....chicken dinner.


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## Thelonerider (Sep 24, 2010)

Zachariah said:


> Good answer. Winner.....chicken dinner.


Argh! And I just had all that Turkey!


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## Guest (Dec 1, 2014)

Thelonerider said:


> With rims width I've found the main thing is with a wider rim, the tire sits lower (so you get less cushioning from air volume between the outside and the rim when you hit a bump) but it also sits wider, so your tire surface contacting the ground is (a little) wider.


Tire height does not vary significantly with rim width and a knobby tire's contact with the ground is determined by the tread pattern, not the casing width. While both of these claims sound true, neither of them is true. With road tires the contact patch could become a little wider. Whether that is meaningful is a different question.

Rim width affects how the sidewall behaves, it does not change the size of the tire. People think they are getting a bigger tire because the caliper says they are wider. The height of the casing and the width of the tread stay the same and that's what matters.


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## Shredman69 (Apr 1, 2007)

Thelonerider said:


> I've always founds tire sizing for bicycle tires (road or mountain) to be purely a "guesstimate." You put the same "size" tire on two diff width rims, it will be either shorter and wider, or narrower and taller, etc. In other words the tire "size" is theoretical.
> 
> With rims width I've found the main thing is with a wider rim, the tire sits lower (so you get less cushioning from air volume between the outside and the rim when you hit a bump) but it also sits wider, so your tire surface contacting the ground is (a little) wider.
> 
> ...





Zachariah said:


> Good answer. Winner.....chicken dinner.


Wrong and wrong again. Just stop talking until you do some current research, or better yet, try it out for yourself unstead of speculating and guessing.


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## Thelonerider (Sep 24, 2010)

Shredman69 said:


> Wrong and wrong again. Just stop talking until you do some current research, or better yet, try it out for yourself ..


Okay... Actually, I did try it for myself.

This was based on anecdotal examples in my experience of using diff tires and rims and how the tire sat.

I have not done wider research, but I thought the discussion was started because someone wanted to know what the impact of diff rim size would be on how the bike was felt to perform, which would seem to include effective tire height/width as perceived by the rider in motion, not just measured static results per se.


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## Cayenne_Pepa (Dec 18, 2007)

Shredman69 said:


> Wrong and wrong again. Just stop talking until you do some current research, or better yet, try it out for yourself unstead of speculating and guessing.


Why don't you stop thinking you know everything? I have had 40mm Derbys and I like the 19mm Easton better...what's your explanation for that?


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## Shredman69 (Apr 1, 2007)

Zachariah said:


> Why don't you stop thinking you know everything? I have had 40mm Derbys and I like the 19mm Easton better...what's your explanation for that?


My guess is you are smoking crack. You shouldn't do it, it's bad for you and it clouds your judgment.:nono:


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## TigWorld (Feb 8, 2010)

Zachariah said:


> I have had 40mm Derbys and I like the 19mm Easton better...what's your explanation for that?


You're not drinking enough kool-aid.



Shredman69 said:


> My guess is you are smoking crack. You shouldn't do it, it's bad for you and it clouds your judgment.:nono:


I just don't think you can advance a blanket proposition that wider rims are better period, and that anyone that disagrees is on drugs. It's like saying "tyre X" is better. There are no absolutes and many subjective and personal variables at play.


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## pharmaboy (Nov 11, 2005)

craigsj said:


> Tire height does not vary significantly with rim width and a knobby tire's contact with the ground is determined by the tread pattern, not the casing width. While both of these claims sound true, neither of them is true. With road tires the contact patch could become a little wider. Whether that is meaningful is a different question.
> 
> Rim width affects how the sidewall behaves, it does not change the size of the tire. People think they are getting a bigger tire because the caliper says they are wider. The height of the casing and the width of the tread stay the same and that's what matters.


Why would tread pattern make any difference?

Everything still points to psi being the greater contributor to tyre behaviour over all other inputs. There isn't anything bad about wide rims, except when someone uses it as an excuse to lower their usual running pressure - which wouldn't be such a bad thing ordinarily, but is a recipe for significant expense and disappointment when it's a carbon rim which just don't seem to enjoy rock strikes


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## Mountain Cycle Shawn (Jan 19, 2004)

Thelonerider said:


> I've always founds tire sizing for bicycle tires (road or mountain) to be purely a "guesstimate." You put the same "size" tire on two diff width rims, it will be either shorter and wider, or narrower and taller, etc. In other words the tire "size" is theoretical.
> 
> With rims width I've found the main thing is with a wider rim, the tire sits lower (so you get less cushioning from air volume between the outside and the rim when you hit a bump) but it also sits wider, so your tire surface contacting the ground is (a little) wider.
> 
> ...


Is this a joke?


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## WoodstockMTB (Oct 5, 2010)

Bikes are no different than golf, tennis, skiing, etc. There needs to be constant change in equipment to keep the industry alive. Sometimes that change is arbitrary. Some things come along and change the game and matter, but most are just incremental and perceived in value.

If I could afford it, I'd have myself a nice 23mm carbon Nox hoop laced to I9 hubs for a 1470g 29" wheel that will do just about 99.9999% of what I need. 30mm internal will only gain me weight for what I ride, but that doesn't mean it doesn't work for those who want it.

Let's try to remember its about having fun and being healthy.


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## Shredman69 (Apr 1, 2007)

TigWorld said:


> You're not drinking enough kool-aid.
> 
> I just don't think you can advance a blanket proposition that wider rims are better period, and that anyone that disagrees is on drugs. It's like saying "tyre X" is better. There are no absolutes and many subjective and personal variables at play.


Yes, I can and yes they are. Saying skinny rims are better than wide (especially wide carbon) rims is like saying rim brakes are better than disc brakes. It's just not true and anyone who thinks it is, is high, hugely uninformed or has hit their head one too many times.

Wide carbon rims being better is just a fact. 
P.S. wide carbon rims are as light or lighter than skinny aluminum rims. They are also stiffer and stronger.


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## Shredman69 (Apr 1, 2007)

Mountain Cycle Shawn said:


> Is this a joke?


IKR! Seems like it must be, but sadly, I don't think it is.


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## aerius (Nov 20, 2010)

Shredman69 said:


> Wide carbon rims being better is just a fact.


If they're truly that good then every top 20 DH and Enduro racer would be using them. 
They're not.


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## Shredman69 (Apr 1, 2007)

aerius said:


> If they're truly that good then every top 20 DH and Enduro racer would be using them.
> They're not.


They don't have much of a choice when their sponsors don't make them,,,yet.


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## TigWorld (Feb 8, 2010)

Shredman69 said:


> Wide carbon rims being better is just a fact...


So why isn't everyone running fatbike rims at 50mm, 70mm or 90mm wide if wider is always better? There must be some point at which "wide" becomes too-wide.

As as for being uninformed, I've got Syntace W35 rims and I've got Stans 21mm internal rims and I've done many back-to-back comparisons and each has their advantages and disadvantages. Your over-simplified bleating is just not right. Its horses for courses and if you think that wider is always better then I'm afraid you're the one who has hit his head one too many times or should put down the crack pipe.

If you like your wide carbon rims (whatever internal width they are) for the riding you do then good luck to you, but to resort to name calling is just weak. It just makes you sound like some sort of enduro-mag reading wannabe who isn't prepared to discuss things rationally because he's just blown his piggy bank money on a new set of rims.

So tell us then, how wide is too wide?


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## aerius (Nov 20, 2010)

Shredman69 said:


> They don't have much of a choice when their sponsors don't make them,,,yet.


Maybe you'd like to explain why Anne-Caroline Chausson runs Mavic wheels when she's sponsored by Ibis and can use their wide carbon wheels.


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## shiggy (Dec 19, 1998)

aerius said:


> Maybe you'd like to explain why Anne-Caroline Chausson runs Mavic wheels when she's sponsored by Ibis and can use their wide carbon wheels.


Simple.
Because she is also sponsored by Mavic.


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## Lelandjt (Feb 22, 2008)

Zachariah said:


> Why don't you stop thinking you know everything? I have had 40mm Derbys and I like the 19mm Easton better...what's your explanation for that?


Boy, I don't know what to say to this. I could see liking a 23mm rim but 19? And to pick Easton of all examples? I've seen so many broken Easton nipples and rear hubs. If it's working for you great but I think you'd like some 23-26mm wide carbon rims laced with 32 bladed spokes to DT 240s better.


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## TigWorld (Feb 8, 2010)

Lejandt said:


> ...bladed spokes...


Seriously? Bladed spokes? More kool-aid. I challenge anyone to tell the difference in a blind test between CX-Rays , Revs and Lasers (or between super CX-Rays and superspokes).

Anyway, are we going to try to answer the "how wide is too wide?" question or is the utility of this entire thread going to boil down to "go wide dude, its wicked!"


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## Shredman69 (Apr 1, 2007)

aerius said:


> Maybe you'd like to explain why Anne-Caroline Chausson runs Mavic wheels when she's sponsored by Ibis and can use their wide carbon wheels.


Really? Because she gets paid extra to be sponsored by Mavic.


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## jester6578 (Mar 15, 2010)

For reference, I have a set of the Roval Fattie 27.5 wheels and love them. I keep them set up with wide tires (2.3 minimum) and low pressure (14/16psi) and they've been amazing. I also have a pair of the Roval SL 29er wheels (21mm internal) that I use on my 29er and cross bikes.



Thelonerider said:


> I would assume narrower wheels would be faster and wider would offer slightly wider contact patch with the ground. Also wider rims might be more durable and less prone to go out of true. But for most riders who don't race and are just recreational riders or just riding around, the benefit would be with narrower rims, which would likely be lighter, have less rotating mass, and be easier to accelerate or ride uphill or over obstacles like rocks and roots.


I would actually argue exactly the opposite conclusions. Narrower rims can be lighter (fractionally) and could accelerate quicker - but these are traits racers would look for over an "average" rider. Greater durability, bigger contact patch, and greater traction would be of a greater benefit to someone just going out for a ride on their favorite trail - who maybe wanted to push themselves on harder terrain. Unless you're talking about a significant drop in weight, the traction gained from the wider ties/less pressure far out weights any additional weight when climbing over rocks and roots. [Note: I'm talking about rims with similar construction. A heavy, wide, alloy rim vs. a skinny carbon racing wheel is a comparing apples to tomatoes.]



Zachariah said:


> Why don't you stop thinking you know everything? I have had 40mm Derbys and I like the 19mm Easton better...what's your explanation for that?


Can I ask why you liked the Eastons better? This is a sincere question, not a baited one. What type of riding do you prefer?

My personal experience with the wide rims is that I had to drop pressure WAY more that I thought I should to get them to feel good. I also wouldn't want to run anything less than a 2.3 (or wide 2.2) tire. With too skinny of a tire, the side knobs start to dig in too much when you don't need them. Rotating weight can also be a factor. The Derby's aren't heavy, but they also aren't light either.



TigWorld said:


> If you like your wide carbon rims (whatever internal width they are) for the riding you do then good luck to you, *but to resort to name calling is just weak. It just makes you sound like some sort of enduro-mag reading wannabe who isn't prepared to discuss things rationally because he's just blown his piggy bank money on a new set of rims.*


Truth.

These forums can be great to discuss new gear and in different permutations than any one of us (except maybe Francois) will ever be able to try on our own. But y'all need to be open to differing opinions.



TigWorld said:


> So why isn't everyone running fatbike rims at 50mm, 70mm or 90mm wide if wider is always better? There must be some point at which "wide" becomes too-wide...
> 
> ...tell us then, how wide is too wide?


I think this is a damn good question. And it might be getting us into a 26 v 27.5 vs 29er realm of debate. That there is no right or wrong answer, just different strokes for different folks.

Wider (w/ wider tires) = lower pressure/higher contact patch but with potentially higher weight and greater rolling resistance.

Skinnier = lighter, quicker accelerating, but having to run higher pressure and giving up traction in situations.

I could be wrong, but since I don't have a bad thing to say about my Fatties, maybe Specialized did find the sweet spot in their research for all round riding at 30mm internal width.

Next summer I want to try another permutation: I'm building up a lightweight 29er and I want to try wide rims with lower profile tires. Lower profile tires would have lower rolling resistance, but it's always been at the cost of traction compared to tires with bigger knobs. I want to see if I can get that low rolling resistance, then boost the traction with lower psi and greater contact patch. Has anyone played around with this?


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## aerius (Nov 20, 2010)

jester6578 said:


> Next summer I want to try another permutation: I'm building up a lightweight 29er and I want to try wide rims with lower profile tires. Lower profile tires would have lower rolling resistance, but it's always been at the cost of traction compared to tires with bigger knobs. I want to see if I can get that low rolling resistance, then boost the traction with lower psi and greater contact patch. Has anyone played around with this?


Yeah, back in the 90s. XC semi-slick tires on 1.5" wide single wall rims. It was not my idea of fun and I don't see any reason to go back to a similar setup, albeit with a lighter & stronger modern rim. Differences were small, if any, it's not like I could drop 5-10 psi and be 5 minutes faster on my half hour test loop or make a bunch of climbs that I couldn't make on skinny rims.


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## jester6578 (Mar 15, 2010)

aerius said:


> Yeah, back in the 90s. XC semi-slick tires on 1.5" wide single wall rims. It was not my idea of fun and I don't see any reason to go back to a similar setup, albeit with a lighter & stronger modern rim. Differences were small, if any, it's not like I could drop 5-10 psi and be 5 minutes faster on my half hour test loop or make a bunch of climbs that I couldn't make on skinny rims.


Do you mind sharing which rims/tires you tried out? And how much less pressure you used?

Thanks!


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## Shredman69 (Apr 1, 2007)

jester6578 said:


> For reference, I have a set of the Roval Fattie 27.5 wheels and love them. I keep them set up with wide tires (2.3 minimum) and low pressure (14/16psi) and they've been amazing. I also have a pair of the Roval SL 29er wheels (21mm internal) that I use on my 29er and cross bikes.
> 
> I would actually argue exactly the opposite conclusions. Narrower rims can be lighter (fractionally) and could accelerate quicker - but these are traits racers would look for over an "average" rider. Greater durability, bigger contact patch, and greater traction would be of a greater benefit to someone just going out for a ride on their favorite trail - who maybe wanted to push themselves on harder terrain. Unless you're talking about a significant drop in weight, the traction gained from the wider ties/less pressure far out weights any additional weight when climbing over rocks and roots. [Note: I'm talking about rims with similar construction. A heavy, wide, alloy rim vs. a skinny carbon racing wheel is a comparing apples to tomatoes.]
> 
> ...


To clear up one more myth, wider tires with lower pressures actually have lower rolling resistance than narrow tires with higher pressures when riding in offroad conditions.

Rolling resistance - Schwalbe Professional Bike Tires

http://forums.mtbr.com/wheels-tires...r-tires-reduce-rolling-resistance-604387.html


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## jester6578 (Mar 15, 2010)

Shredman69 said:


> To clear up one more myth, wider tires with lower pressures actually have lower rolling resistance than narrow tires with higher pressures when riding in offroad conditions.
> 
> http://forums.mtbr.com/wheels-tires...r-tires-reduce-rolling-resistance-604387.html


Yes, but that is very terrain/conditions dependent. And at what point do you get to diminishing returns?

I like wider rims, but blanket statements do a disservice to your argument. Don't you dare claim that you've ridden a fatbike at 7psi and that it has the same rolling resistance as a cross bike at 35psi in all "offroad conditions"

Also, the links in that thread no longer work.


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## Shredman69 (Apr 1, 2007)

Yes, but that is very terrain/conditions dependent. And at what point do you get to diminishing returns?

On smooth pavement.

Rolling resistance - Schwalbe Professional Bike Tires


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## aerius (Nov 20, 2010)

jester6578 said:


> Do you mind sharing which rims/tires you tried out? And how much less pressure you used?


According to my notes, the narrow rims were Mavic 230 and the wide ones were Arayas of some sort. Tires were Ritchey Speedmax 1.9" and Z-max 2.1". The Speedmax was always in the 35-40psi range, any lower and it pinch flatted, Z-max was 30-35psi, pinch flatted as well when I went lower. I'd have to plug the numbers into a spreadsheet to be sure, but it looks like all the lap times are within the margin of error.


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## jester6578 (Mar 15, 2010)

Shredman69 said:


> On smooth pavement.
> 
> Rolling resistance - Schwalbe Professional Bike Tires


From the link:


> The lower the inflation pressure, the lower the rolling resistance. This applies equally on hard gravel roads and soft forest tracks. Explanation: A tire with low inflation pressure can adapt better to a rugged surface. It sinks into the ground less and the whole rotational mass is retarded much less by the uneven surface.
> 
> Tires with a smaller diameter have a higher rolling resistance with the same tire pressure, because tire deformation is proportionally greater. In other words the tire is "less round".


Thanks for the link - it's an interesting way to think about it. And I realized in my last response I wasn't taking into account rotating mass.



aerius said:


> According to my notes, the narrow rims were Mavic 230 and the wide ones were Arayas of some sort. Tires were Ritchey Speedmax 1.9" and Z-max 2.1". The Speedmax was always in the 35-40psi range, any lower and it pinch flatted, Z-max was 30-35psi, pinch flatted as well when I went lower. I'd have to plug the numbers into a spreadsheet to be sure, but it looks like all the lap times are within the margin of error.


Ah, so you were running tubes? And it looks like the Arayas only run ~20mm internal? Thanks!


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## Lelandjt (Feb 22, 2008)

TigWorld said:


> I challenge anyone to tell the difference in a blind test between CX-Rays , Revs and Lasers (or between super CX-Rays and superspokes.


I can tell a big difference when building or truing a wheel. Thin, round spokes wind up, especially at the very nigh tensions carbon rims allow. Bladed spokes allow you to use a nice little holder so you can get an exact amount of turn on each nipple. Even if they weren't 50g+ per wheel lighter than 14/15 spokes I'd always use them just for that reason. I never used spokes thinner than 14/15 cuz of the wind up and they just didn't seem to build into strong, stiff wheels. You only saw XC racers using them. What turned me onto the bladed spokes that fit normal hubs was when downhillers started using CX-Rays. I've now used Sapim CX-Rays, DT Aerolites, and Pillar 1420s.

To answer the other half of your question I decided a decade ago that 29-30mm internal rims feel good with DH width tires and 23-25mm rims feel good with XC tires. There was a period in DH where we had some very wide rims to try and I preferred the 29mm Mavic 729 and 30mm Intense Mag 30 to all others when paired with Minion DHF 2.7s (really 2.5"). Back then I was liking the 23-25mm wide Sun Singletrack and Rynolite rims with my 2.2" XC tires.
Now I use Light-Bicycle 30mm rims on my DH and enduro bikes and 23mm rims on my XC bike. I'll bump the latter up to 25mm when it needs new rims if someone makes a sub 400g hookless 27.5 model.


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## hoolie (Sep 17, 2010)

In this blind test, the wheels would need to be covered? Or just go for it with a blind fold on?


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## Shredman69 (Apr 1, 2007)

hoolie said:


> In this blind test, the wheels would need to be covered? Or just go for it with a blind fold on?


Blindfold all the way! Do it.:yesnod:


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## TigWorld (Feb 8, 2010)

Lelandjt said:


> Sapim CX-Rays, DT Aerolites, and Pillar 1420s


Those spokes are all no stronger than their 2.0 / 1.5 mm round equivalents from which they are made (although manufacturers do have some higher fatigue life claims). A CX-Ray is just a flattened Laser that costs three times the price and an Aerolite is just a flattened Rev. They are just as elastic/flexy as any other spoke with the same cross sectional area at the thinnest point. Flattening a round spoke does not magically alter the properties of the metal its made of for the purposes of the present discussion.

If spoke wind-up is an issue for you when building then that's just down to technique and inadequate stress relief during the build. Flat bladed spokes are a crutch in that regard, but if you need that crutch and are happy to pay 3x as much, for no net performance gain then go for it.


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## Lelandjt (Feb 22, 2008)

Pillar 1420s cost $1.60 per spoke. Not so bad. I haven't seen one of these types of bladed spokes break yet but have seen plenty of broken Revs. Of course Revs are still more common. I've also never seen a DH or enduro wheel built with Revs but CX-Rays and Aerolites are pretty popular. Are you hating just cuz of the price or do you love doing the angle-pinch to keep Revs from winding up? Have you used Revs to build a carbon rim or DH rim that can take really high tension? Seems like a nightmare.


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## TigWorld (Feb 8, 2010)

Lelandjt said:


> ...Are you hating just cuz of the price or do you love doing the angle-pinch to keep Revs from winding up? Have you used Revs to build a carbon rim or DH rim that can take really high tension? Seems like a nightmare.


Not hating, just don't like the perpetuation of urban myths or other claims that have no scientific rigor behind them. I haven't built any carbon wheels but have built wheels that can take really high tension. But high spoke tension is another urban myth debunked many times in the past. As long as you have enough tension that a spoke will not go slack while riding, then any higher tension will not result in a stiffer wheel - Wheel Stiffness Test

On the subject of carbon rims and wheel stiffness as perceived by the rider, there's some interesting reading here: Debunking Wheel Stiffness - Slowtwitch.com


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## bholwell (Oct 17, 2007)

Lelandjt said:


> I can tell a big difference when building or truing a wheel. Thin, round spokes wind up, especially at the very nigh tensions carbon rims allow. Bladed spokes allow you to use a nice little holder so you can get an exact amount of turn on each nipple.


I don't claim to be an expert wheel builder, but I have had a couple sets of carbon hoops built up by respected wheel builders, and they both suggested bladed spokes for that very reason. Makes sense to me.



Lelandjt said:


> To answer the other half of your question I decided a decade ago that 29-30mm internal rims feel good with DH width tires and 23-25mm rims feel good with XC tires. There was a period in DH where we had some very wide rims to try and I preferred the 29mm Mavic 729 and 30mm Intense Mag 30 to all others when paired with Minion DHF 2.7s (really 2.5"). Back then I was liking the 23-25mm wide Sun Singletrack and Rynolite rims with my 2.2" XC tires.
> Now I use Light-Bicycle 30mm rims on my DH and enduro bikes and 23mm rims on my XC bike. I'll bump the latter up to 25mm when it needs new rims if someone makes a sub 400g hookless 27.5 model.


I have a feeling that most riders (and rim manufacturers) will eventually settle on the widths for the applications you've described. A possible exception to this might be if a company designs a rim in conjunction with a tire (similar to what was done with fat tires).


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## meltingfeather (May 3, 2007)

Lelandjt said:


> Pillar 1420s cost $1.60 per spoke. Not so bad. I haven't seen one of these types of bladed spokes break yet but have seen plenty of broken Revs. Of course Revs are still more common. I've also never seen a DH or enduro wheel built with Revs but CX-Rays and Aerolites are pretty popular. Are you hating just cuz of the price or do you love doing the angle-pinch to keep Revs from winding up? Have you used Revs to build a carbon rim or DH rim that can take really high tension? Seems like a nightmare.


It's not a nightmare at all (I've built plenty). If you're willing to buy more expensive spokes so your wheelbuilder can use their cute little holder, that's your choice. There is nothing about bladed spokes that affords you, the end user, a benefit.
Incidentally, what benefit do you think a rider with carbon rims gets out of "really high tension," particularly in the overwhelming majority of cases where normal tension in the range of 110-120kgf is plenty adequate?


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## Lelandjt (Feb 22, 2008)

meltingfeather said:


> Incidentally, what benefit do you think a rider with carbon rims gets out of "really high tension," particularly in the overwhelming majority of cases where normal tension in the range of 110-120kgf is plenty adequate?


My experience is with Light-Bicycle carbon rims, Mavic 729s, and Intense Mag 30s that could take really high tension (basically the alloy nipples become the limiting factor) versus Notubes rims that couldn't go over 95-125 depending on model. The stiff rims with high tension resulted in a laterally stiff feeling wheel that didn't go out of true. The low tension NoTubes wheels would go out of true or round especially with hard use like big jump landings.

When you consider that as a wheel spins (or lands from a big jump) the bottom spokes are unloaded while the top ones are loaded it makes sense that a higher spoke tension will reduce the amount of vertical tension/slack that's happening. Despite what the linked articles above say it makes sense that the same holds true for lateral stiffness. A wheel with higher tension certainly feels stiffer than one with low tension and when you look at how lateral cornering force is pulling on the spokes on the bottom/outside of the wheel is makes sense that having those spokes tighter results in less rim deflection.

Regardless of all this theory I can state that all the DT 240/bladed spoke/Light Bicycle wheels I've built for myself and friends have been very light, low maintenance, and felt great. I have yet to find anything better, though of course there's cheaper options if that's your priority.


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## aerius (Nov 20, 2010)

Lelandjt said:


> My experience is with Light-Bicycle carbon rims, Mavic 729s, and Intense Mag 30s that could take really high tension (basically the alloy nipples become the limiting factor) versus Notubes rims that couldn't go over 95-125 depending on model. The stiff rims with high tension resulted in a laterally stiff feeling wheel that didn't go out of true. The low tension NoTubes wheels would go out of true or round especially with hard use like big jump landings.


That's because Stan's rims are soft & weak compared to a Mavic 729, it's the rim, not the spoke tension. A softer more flexible rim (Stan's) will bend more which unloads the spokes and allows them to loosen, that is, in addition to the rim itself bending. It takes far more force to bend a 729 to the point where the spokes will unload & loosen, so even if a Stan's and 729 were both built to the same tension, the Mavic will still be much stiffer, stronger, and better able to stay true.


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## meltingfeather (May 3, 2007)

Lelandjt said:


> When you consider that as a wheel spins (or lands from a big jump) the bottom spokes are unloaded while the top ones are loaded it makes sense that a higher spoke tension will reduce the amount of vertical tension/slack that's happening.


1. the top ones are not loaded in this scenario. the remainder of the spokes in the wheel that do not see the large detensioning do share a roughly equal slight increase, but not the top ones any more than the ones at 3 or 9 o'clock.
2. tension does not reduce the amount of deformation... it changes the point at which the deformation causes slack spokes, and that is a very important difference. this is the important difference that dictates the fact that higher tension does not make stiffer wheels.


Lelandjt said:


> Despite what the linked articles above say it makes sense that the same holds true for lateral stiffness. A wheel with higher tension certainly feels stiffer than one with low tension and when you look at how lateral cornering force is pulling on the spokes on the bottom/outside of the wheel is makes sense that having those spokes tighter results in less rim deflection.


this is another important difference: reality vs. your feelings



Lelandjt said:


> Regardless of all this theory I can state that all the DT 240/bladed spoke/Light Bicycle wheels I've built for myself and friends have been very light, low maintenance, and felt great. I have yet to find anything better, though of course there's cheaper options if that's your priority.


No doubt they build fine wheels... I never said they didn't. They don't offer a benefit over some other options, except the opportunity to spend more money, if that's your priority.



aerius said:


> That's because Stan's rims are soft & weak compared to a Mavic 729, it's the rim, not the spoke tension. A softer more flexible rim (Stan's) will bend more which unloads the spokes and allows them to loosen, that is, in addition to the rim itself bending. It takes far more force to bend a 729 to the point where the spokes will unload & loosen, so even if a Stan's and 729 were both built to the same tension, the Mavic will still be much stiffer, stronger, and better able to stay true.


^^this


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## TigWorld (Feb 8, 2010)

There's also some interesting reading in this article from Nox Composites about vertical compliance and carbon rims - Wheel Building Philosophy and Other Info | Nox Composites Carbon MTB Rims and Wheels

The bottom line seems to be that the carbon rim is twice as radially stiff as the aluminium rim, but the actual amount of deflection for both types of rim is so small as to be imperceptible to humans (eg. 2" root hit at 15mph deflects alu rim by 0.018 inches and carbon rim by 0.009 inches).


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## Lelandjt (Feb 22, 2008)

Clementz just split with Mavic so it'll be interesting to see what his 2015 rims will be made of and how wide they'll be. He told me he likes alloy cuz he can repair dented sidewalls between stages but I haven't heard him comment on width. It reasons that he'll be on something carbon from Sram but I don't know their line.


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## Shredman69 (Apr 1, 2007)

SRAMs top of the line wheel is the Roam 60, which they call a wide angle rim, but it's only 21mm internal, (28ex).


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## JLF1200 (Sep 16, 2009)

jeffreyjhsu said:


> I'm jumping into this argument late but.. I'm a x-country rider weighing about 165 lbs. I've been riding my 29r American Classic Wide Lightning wheels for almost a year now. Much more traction everywhere, better cornering, smoother ride AND I can run 5lbs less tire pressure. 19mm inner rim diameter to 29.5 makes a HUGE difference.


I think this post is the most telling for this (very long) thread.

Lots of people are calling for experience to trump theory here, so I'll just relay my anecdotal experience: all the guys I know who rave about super wide rims are XC and "light trail" riders, mostly on 29ers. All the guys I know who are calling BS on the "hype" are serious descenders, cat 1 DH and enduro guys, etc. The latter group invariably says they hate that the width closes up the drift patch of their tires. The former group mostly doesn't even know what a drift patch is or what it does, and wouldn't ride a tire with such a feature anyway because they tend to roll really slowly. This is just my little world, but it's 100% consistent so far.

I don't have the money to experiment with 38mm wide carbon rims, so this is all I have to go off of. And what it seems like to me is that there are advantages and disadvantages to riding giant width rims (gasp!). Width seems to work out for guys whose average trail speeds are lower, who ride tires with rounder profiles and smaller side lugs. Whereas it seems to bother guys who are leaning their bikes over more because of the speed they carry, (and it's worth noting that a HUGE percentage of these guys are riding Minions or Minion clones like Butchers, or High Rollers, or something that looks like it's designed to shovel dirt sideways at 30mph).

Someone else just pointed out that most of the "wide" rims the pro DH and enduro riders are using are still within the 25mm internal width zone. Makes sense, no?


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## Guest (Jan 7, 2015)

JLF1200 said:


> ...I'll just relay my anecdotal experience...I don't have the money to experiment with 38mm wide carbon rims, so this is all I have to go off of...


Incredible anecdotal experience there. What would we have done without it?

Sometimes perspectives, though explainable, are naive...even among racers. No one would want wagon wheels...until they did. Progress frequently requires relearning and that creates resistance.

What is hated today becomes the standard tomorrow. Today's "long, low, and slack" was yesterday's sluggish handling, wheel flopping, pedal crashing nightmare. Sometimes prejudice is a better explanation. Don't think just because someone says something that it's true.


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## Mountain Cycle Shawn (Jan 19, 2004)

What is true, is they need to start making tires for these wide rims. Then we'll really see some progress.

BTW, I Don't think JLF1200 is far off.


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## JLF1200 (Sep 16, 2009)

craigsj said:


> Incredible anecdotal experience there. What would we have done without it?


Nice job editing out the actual anecdotes. What would we do without your asshatty sarcasm, though?



> Sometimes perspectives, though explainable, are naive...even among racers.


Sure, but clocks don't lie. We can always count on MTBR Trail Brah coming here to talk about how awesomely squishy his 40mm rim makes his tires feel and therefore it's "better," but even if he swears he's faster it's pretty subjective. Someone who competes will generally offer a more valuable opinion regarding performance than someone who doesn't. And the opinion I'm hearing from competitive gravity riders is that super wide rims don't do good things to their tires. Up to you whether you choose to believe that all those guys are "naive" or deluded or whatever. I think that suggests your own bias more than anything else.

The point I was trying to make was that contexts are rarely equal in a thread like this. Some dude who rides XC and carries an average speed of 7mph for 2 hours and spends most of that time climbing has vastly different demands for his wheels and tires than someone who races balls out for 3-15 mins at a time down a fall line and couldn't care less about going uphill. They're in different worlds. Not sure why I have to beat you over the head with this, unless you're just a troll.



> Don't think just because someone says something that it's true.


So you talk sh!t on my post for not being insightful enough, and then drop groundbreaking pearls of wisdom like this?


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## JACKL (Sep 18, 2011)

I'm running Flow Exs (which used to be considered wide) and Hans Dampf 2.35s. Coming from 17mm internal width rims they were a huge improvement. However with these particular tires, 25mm internal width seems just about right to me. I don't feel any wobble at the limit like I did on skinny rims. However I'm not looking for more lateral stability. On a fast bumpy corner, I want some lateral give in the tire.

At least I think I do. I'll have to actually run the wider rims to know for sure. For now I ain't gonna fix what's not broke.


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## Guest (Jan 7, 2015)

JLF1200 said:


> Nice job editing out the actual anecdotes. What would we do without your asshatty sarcasm, though?


You provided no anecdotes, much less anecdotes of your own. Perhaps you should understand what one is.



JLF1200 said:


> Someone who competes will generally offer a more valuable opinion regarding performance than someone who doesn't.


Only if their opinion is on how to compete. Racers generally aren't engineers and frequently know nothing about what they ride.



JLF1200 said:


> Up to you whether you choose to believe that all those guys are "naive" or deluded or whatever. I think that suggests your own bias more than anything else.


Yes, it is up to me and I prefer not to defer to an authority whose understanding is completely unknown and unproven, who are often paid to ride what they ride and told what to say about it. Furthermore, I'm even more uninterested in some unknown guy's summary of those opinions that he claims are his own "anecdotes". Some people lack critical thinking skills...like you.



JLF1200 said:


> Not sure why I have to beat you over the head with this, unless you're just a troll.


If you can't make your case you can always resort to insults. Perhaps you can stomp your feet and scream "Mommy" while you are at it.



JLF1200 said:


> So you talk sh!t on my post for not being insightful enough, and then drop groundbreaking pearls of wisdom like this?


Can't help it if you don't understand it. If you can't demonstrate that you even understand the words you use, why should anyone care what you say?


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## JLF1200 (Sep 16, 2009)

craigsj said:


> You provided no anecdotes, much less anecdotes of your own. Perhaps you should understand what one is.
> 
> Only if their opinion is on how to compete. Racers generally aren't engineers and frequently know nothing about what they ride.
> 
> ...


Ah, now I see what sort of troll you are: the angry engineer, high analytical intelligence, low emotional intelligence, can't refrain from swiping at people on internet forums when you feel they haven't maintained scientific purity in the discussion. A quick search of your posts shows this pattern. Your day job coworkers must love you.



> Only if their opinion is on how to compete. Racers generally aren't engineers and frequently know nothing about what they ride.


I disagree, they are quite intuitive about their equipment and certainly more knowledgable about performance than the enthusiast, but it's understandable that someone like you would want to devalue the observations of faster riders in the face of engineering calculations. It's how your ego protects you from feelings of inadequacy that arise when you get involved with sports. Product testing and rider feedback on the race circuit is a waste of time in your mind, I assume?

The OP is a competitive DH rider, and I was relaying reports from other competitive DH riders about rim width. Pretty valuable and relevant to the topic, if you're the "ignorant" sort who actually races bikes, like we are. Maybe you aren't, and that's ok. You might consider just cordially proposing why my particular observation didn't make sense mathematically, since that's your happy place.

Thing is, this is a fairly simple concept I'm trying (for the third time) to relay: that gravity tire designs (think Minions) don't jive with super wide rims, specifically because the slight change in shape causes the drift channel to not perform as intended and the tire loses bite. Maybe you can't ride fast enough to experience this for yourself, but I'm sure you could do something constructive, like run a MATLAB simulation.:thumbsup:


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> Incredible anecdotal experience there. What would we have done without it?
> 
> Sometimes perspectives, though explainable, are naive...even among racers. No one would want wagon wheels...until they did. Progress frequently requires relearning and that creates resistance.
> 
> What is hated today becomes the standard tomorrow. Today's "long, low, and slack" was yesterday's sluggish handling, wheel flopping, pedal crashing nightmare. Sometimes prejudice is a better explanation. Don't think just because someone says something that it's true.


It was yesterday's sluggish handling, wheel flopping, pedal crushing nightmare, because other changes had to be made for it to work properly. Those changes were made, people learned and now it works great. JLF1200 is correct. The DH and Enduro people aren't embracing this yet, because it doesn't work for them. There are other things that they are slow to embrace. DH racing is extreme and on the ragged edge. These guys aren't going to use something that doesn't work well. It's just going to take some time till the tire makers can make tires for these wide rims.


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## JLF1200 (Sep 16, 2009)

Mountain Cycle Shawn said:


> It was yesterday's sluggish handling, wheel flopping, pedal crushing nightmare, because other changes had to be made for it to work properly. Those changes were made, people learned and now it works great. JLF1200 is correct. The DH and Enduro people aren't embracing this yet, because it doesn't work for them. There are other things that they are slow to embrace. DH racing is extreme and on the ragged edge. These guys aren't going to use something that doesn't work well. It's just going to take some time till the tire makers can make tires for these wide rims.


Thank you-- that's all I was trying to say! Rim choice isn't going to trump tire choice for gravity riders, ever. And the Minion design is probably ridden 3:1 against all others. Tire manufacturing isn't the fastest thing to adapt, so we might end up in a chicken/egg situation (no demand/no offerings) unless a small/scrappy company steps in with a wide-rim, gravity-oriented design.

Someone like bholwell could probably comment on whether this would be as simple as spacing the side lugs away from the center or if it would also involve a differently shaped casing, or other changes.


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## Yody (Jan 21, 2008)

jlf1200 said:


> ah, now i see what sort of troll you are: The angry engineer, high analytical intelligence, low emotional intelligence, can't refrain from swiping at people on internet forums when you feel they haven't maintained scientific purity in the discussion. A quick search of your posts shows this pattern. Your day job coworkers must love you.
> 
> I disagree, they are quite intuitive about their equipment and certainly more knowledgable about performance than the enthusiast, but it's understandable that someone like you would want to devalue the observations of faster riders in the face of engineering calculations. It's how your ego protects you from feelings of inadequacy that arise when you get involved with sports. Product testing and rider feedback on the race circuit is a waste of time in your mind, i assume?
> 
> ...


lmao



jlf1200 said:


> i think this post is the most telling for this (very long) thread.
> 
> Lots of people are calling for experience to trump theory here, so i'll just relay my anecdotal experience: All the guys i know who rave about super wide rims are xc and "light trail" riders, mostly on 29ers. All the guys i know who are calling bs on the "hype" are serious descenders, cat 1 dh and enduro guys, etc. The latter group invariably says they hate that the width closes up the drift patch of their tires. The former group mostly doesn't even know what a drift patch is or what it does, and wouldn't ride a tire with such a feature anyway because they tend to roll really slowly. This is just my little world, but it's 100% consistent so far.
> 
> ...


+100


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## Yody (Jan 21, 2008)

I rode minions on the new Ibis 41MM wide rims. It was almost like the outside knobs were pointing straight up instead of out to the side. Probably good for people who ride most of the time straight up and down.....


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## Guest (Jan 8, 2015)

JLF1200 said:


> Ah, now I see what sort of troll you are: the angry engineer, high analytical intelligence, low emotional intelligence, can't refrain from swiping at people on internet forums when you feel they haven't maintained scientific purity in the discussion. A quick search of your posts shows this pattern. Your day job coworkers must love you.


They do. Unlike you, I'm not so desperate that I feel compelled to search your background to dream up insults. I'd suggest your time is better spent improving your vocabulary.



JLF1200 said:


> I disagree, they are quite intuitive about their equipment and certainly more knowledgable about performance than the enthusiast, but it's understandable that someone like you would want to devalue the observations of faster riders in the face of engineering calculations.


I'm not sure what "engineering calculations" you are speaking of nor "the observations of faster riders". I have seen no examples of either.



JLF1200 said:


> It's how your ego ...


Look who's talking. If there's anything that can be counted on, it's remedial posters who shout "troll", hurl insults, and project their own inadequacies on others when they don't get their way. It's your ego that's the problem here.



JLF1200 said:


> The OP is a competitive DH rider, and I was relaying reports from other competitive DH riders about rim width.


I've followed this thread since the beginning and don't need your help in forming an opinion of the OP's position nor do I have any reason to trust that you were "relaying" anyone's opinion. What are you? The official spokesman for professional downhill riders?



JLF1200 said:


> ...that gravity tire designs (think Minions) don't jive with super wide rims, specifically because the slight change in shape causes the drift channel to not perform as intended and the tire loses bite.


But you have no evidence that this is true generally, if true at all, as opposed to being true only for a select few tires nor can you possibly know what has been tested for these people you claim to be "relaying" information for...plus you've admitted to having no experience with this yourself nor do you intend to gain any. Your opinion is less interesting than everyone else's.



JLF1200 said:


> Maybe you can't ride fast enough to experience this for yourself, but I'm sure you could do something constructive, like run a MATLAB simulation.:thumbsup:


Ah yes, the old "your don't agree because you are an inferior rider" argument. Another classic that the ignorant trot out.

Just think...if you knew what an anecdote was all this could have been avoided. A high school education is a wonderful thing.


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## Guest (Jan 8, 2015)

Mountain Cycle Shawn said:


> It was yesterday's sluggish handling, wheel flopping, pedal crushing nightmare, because other changes had to be made for it to work properly. Those changes were made, people learned and now it works great.


Like what exactly? What changes were made to get a low BB to reduce pedal strikes? What changes were made to make a longer FC fit the same rider? All that's changed is fork offset.

When the Tallboy first came out it took a beating here from many posters for its "too low" BB. Now it's not only not "too low", it's not even low if you believe a post made just today in another thread. Face it, it's popular opinion that's changed on this, nothing technical. "Long, low, and slack" is a trend, not a technical development.



Mountain Cycle Shawn said:


> JLF1200 is correct. The DH and Enduro people aren't embracing this yet, because it doesn't work for them.


You are not agreeing with his position. He claims they don't "embrace" it because it doesn't work...period. There is no "yet" in his claim, there is only speculation why we "slow riders" can't understand why wide rims are bad.



Mountain Cycle Shawn said:


> It's just going to take some time till the tire makers can make tires for these wide rims.


That's very likely a reason, but also time to learn how to take advantage of new capabilities. Given time and resources, DH riders will want to take advantage of additional traction, not intentionally do without it.

There is another active thread here where a specialized tire engineer says that tires are designed with only one target rim width and that varying that width does have significant effects in this regard. Those same tire designers work to make cornering grip progressive and will have to adapt as rim changes improve traction at the limits. It's a good problem to have despite what some "fast riders" think.


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## Guest (Jan 8, 2015)

Yody said:


> I rode minions on the new Ibis 41MM wide rims. It was almost like the outside knobs were pointing straight up instead of out to the side. Probably good for people who ride most of the time straight up and down.....


Another rider who thinks that how a tire looks when it's not touching the ground determines how it performs. You think a tire maintains it's perfect, curved profile when it's in contact with the ground?


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## pharmaboy (Nov 11, 2005)

craigsj said:


> That's very likely a reason, but also time to learn how to take advantage of new capabilities. Given time and resources, DH riders will want to take advantage of additional traction, not intentionally do without it.
> 
> There is another active thread here where a specialized tire engineer says that tires are designed with only one target rim width and that varying that width does have significant effects in this regard. Those same tire designers work to make cornering grip progressive and will have to adapt as rim changes improve traction at the limits. It's a good problem to have despite what some "fast riders" think.


Just as an aside I run a tallboy and a jet rdo, and the BB height makes them pretty different bikes for me.

I'm aware of one tyre designer on this forum, and mostly he's ignored on this thread - on the basis of him knowing **** loads more than me on the topic, his is the opinion that I take most from.

One disadvantage that engineers have, is they tend to ignore behavioural aspects or reviews. There is lot to be learnt from anecdote but a little thought has to go into it sometimes to seperate causes from anecdotal observation.

As far as downhill goes, it's reasonable that tyre design effects wide rim usage more than any pros or cons of wide rims. BUT, joe public will never hear results of in field testing between bike manufacturers and riders unless it agrees with their marketing stance .

No better example than specializeds 29er test on youtube. It's a mistake to assume it's faked, but you are only seeing it because it agreed with their aims - if it had gone the other way, cutting room floor. The filter is as important as the experiment itself.

For us and this topic, the Mtb press is the filter - as they are with other current trends like wide bars, short stems , 27.5, and whatever else is cool this season.

Where critical thinking becomes cynicism though is non too obvious


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## Shredman69 (Apr 1, 2007)

Don't say wide rims don't work unless you've tried them, bottom line. Wide rims, (carbon) are a game changer. I use to have 3 sets of medium width, (25.5) aluminum wheelsets. After I destroyed another aluminum rim, I gave light bikes 33 wide carbons a try. They were such a huge improvement, that I eventually changed all 3 wheel sets. I now have 2 sets of the 33's and 1 set of 38's (for DH). I'm not a pro, but I've been riding and racing Motocross and mountain bikes (DH) on and off since I was a kid and I'm not slow DH. 2 of my riding buddies have now made the switch and they have the had same great experiences, all positive, zero negatives. You can run lower pressures, (tubless) because of the higher volumes, the tire conforms to the trail, like in high speed corners, the sidewall is better supported and doesn't roll like it does on a skinny rim, carbon is much stiffer and the wheel holds a line better....I could go on and on, it's the single best improvement I've made to any of my bikes other than suspension for the first time in the early 90's.


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## meltingfeather (May 3, 2007)

I tend to agree that perceptions in many ways change much more than technical reality. Compare my 2003 GF Mt. Tam 29er, which in this forum is characterized as a "twitchy school bus with old school geometry" to current XC 29ers that are "dialed active and flickable fun machines" and you find little difference, except of course for the words used to describe them.
I also agree that it takes riders (including pros) time to adapt to any innovation and invariably there are TONS of haters on the front end... like there were for suspension, clipless pedals, disc brakes, large volume tires, 29ers... the list goes on and on.


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## JLF1200 (Sep 16, 2009)

craigsj said:


> Another rider who thinks that how a tire looks when it's not touching the ground determines how it performs. You think a tire maintains it's perfect, curved profile when it's in contact with the ground?


And you think performance isn't affected when the orientation of the side lugs changes a visible amount?


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> Like what exactly? What changes were made to get a low BB to reduce pedal strikes? What changes were made to make a longer FC fit the same rider? All that's changed is fork offset.
> 
> *That just goes to show, you don't know what you're talking about.*
> 
> ...


*No **** Sherlock!*


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## JLF1200 (Sep 16, 2009)

(moved to appropriate thread)


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## Mountain Cycle Shawn (Jan 19, 2004)

Y


JLF1200 said:


> The only explanation for craigsj flipping out over my crime of using the wrong word (or whatever) is that he's a sad troll. I'm not even sure he has a dog in this fight, because I seriously doubt he's ever raced down a mountain on a bicycle in any competive fashion, nor is it likely that he's drifted a tire like a Minion at high speed, so he probably has no idea about the performance issue I'm even referring to.
> 
> I'm not a zealot, I would love to get my hands on some giant rims. The positive reviews can't be ignored and certainly aren't hype. I pretty much live to lay my bike over at speed and it seems like wider rims could provide performance advantages in that regard. However, I also can't ignore the consistent complaints I hear, both directly from other DH racers and reports from pros (such as Jill Kintner) that wide rims don't do good things to their preferred tires, usually tires with drift patch designs, such as Minions.
> 
> ...


Just wait about a year and the tire companies will catch up. In my opinion, they are going to find that a slightly narrower tire will work best. The wide rims seem to work better with a slightly narrower tire.


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## JLF1200 (Sep 16, 2009)

Mountain Cycle Shawn said:


> *No **** Sherlock!*


The only explanation for craigsj flipping out over my crime of using the wrong word (or whatever) is that he's a sad troll. I'm not even sure he has a dog in this fight, because I seriously doubt he's ever raced down a mountain on a bicycle in any competive fashion, nor is it likely that he's drifted a tire like a Minion at high speed, so he probably has no idea about the performance issue I'm even referring to.

I'm not a zealot, I would love to get my hands on some giant rims. The positive reviews can't be ignored and certainly aren't hype. I pretty much live to lay my bike over at speed and it seems like wider rims could provide performance advantages in that regard. However, I also can't ignore the consistent complaints I hear, both directly from other DH racers and reports from pros (such as Jill Kintner) that wide rims don't do good things to their preferred tires, usually tires with drift patch designs, such as Minions.

All I'm saying is these gravity tire designs and the new wider rim designs don't seem to be a great match. And it makes sense that people who ride slower, (I mean "slower" literally, XC riders and the like), wouldn't see these negative effects, nor would they even be riding a tire designed to drift at high speed anyway, so they won't see these negative aspects.

Nobody should take insult from that line of reasoning. I'm just offering a possible explanation for why I'm hearing conflicting reports from two different types of rider.


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## pharmaboy (Nov 11, 2005)

Shredman69 said:


> Don't say wide rims don't work unless you've tried them, bottom line..


So you've been charged by the police, only going to use an attorney who's been inside?

Want to build a house, are you going to choose a builder to do design work rather than an architect?

How about, you need a truck built, obviously a truck driver would be the place you'd start?

Seriously, one of the greatest certainties in this consumer world is that someone who bought something loves it, and recommends it - the only other option is for them to admit they made a mistake and were wrong ( in which case you'll notice they blame the manufacturer or someone else) . You may think that admitting mistakes comes easy, but look at your work colleagues etc - everyone loves their own decisions, hence feedback from happy purchasers is pretty much useless.


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## Shredman69 (Apr 1, 2007)

pharmaboy said:


> So you've been charged by the police, only going to use an attorney who's been inside?
> 
> Want to build a house, are you going to choose a builder to do design work rather than an architect?
> 
> ...


WTF are you talking about??? You are seriously out of your mind man! Just stop. Everything you just said made no sense and does not relate to what I said or have experienced.


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## meltingfeather (May 3, 2007)

*deleted*

nvm


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## oldranger (Apr 14, 2011)

Hi Folks, 
OP here..just saying hi again. I still am subscribed to the thread and always look forward to seeing where the discussion goes. (Still regretting I didn't put 'Downhill' in the Thread Subject, BTW)

Here's where I still stand for 2015 downhill riding/racing: I'm going in to a second year with the DT Swiss FR600 (inner 25mm, outer 32mm). I'm also still going to run 2.5" width Maxxis tires for dry or mixed conditions. Most often this will be the Minion DHF and DHR2 (3c). On rare occasion, there are conditions where I use the High Roller 2.5" 60a in the rear. For mud I use Continental Mud King 2.3 with the center lugs cut just a bit. These tires/rims match very well and the tire flexes predictably on the DT FR600 when I have proper pressures. I run tubeless in the front, with relatively low pressures and no burping problems. I use a Welterweight tube in the rear, and I did not have any pinch flats on the rear tire during the 5 or 6 races I competed in last year. From my perspective this spec is working well for me, and from a race results standpoint I achieved what I was hoping for. Note: I am rebuilding the rear wheel for 2015; the FR600 is a bit soft and light for my 190 pound riding weight and style.

With that said:

What are the options for a wide, downhill spec rim in 27.5" diameter?

Does anyone know if DH compound tires that are specifically designed for these wider rims at a 27.5" diameter are in the 'works'?

(At this point in the evolution of the DH Wheel/Tire system - it seems like if you're going to change rims to get faster, you should probably upsize diameter)

Cheers, 
Andy


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## JLF1200 (Sep 16, 2009)

Shredman69 said:


> Don't say wide rims don't work unless you've tried them, bottom line. Wide rims, (carbon) are a game changer. I use to have 3 sets of medium width, (25.5) aluminum wheelsets. After I destroyed another aluminum rim, I gave light bikes 33 wide carbons a try. They were such a huge improvement, that I eventually changed all 3 wheel sets. I now have 2 sets of the 33's and 1 set of 38's (for DH). I'm not a pro, but I've been riding and racing Motocross and mountain bikes (DH) on and off since I was a kid and I'm not slow DH. 2 of my riding buddies have now made the switch and they have the had same great experiences, all positive, zero negatives. You can run lower pressures, (tubless) because of the higher volumes, the tire conforms to the trail, like in high speed corners, the sidewall is better supported and doesn't roll like it does on a skinny rim, carbon is much stiffer and the wheel holds a line better....I could go on and on, it's the single best improvement I've made to any of my bikes other than suspension for the first time in the early 90's.


You're coming in hot!

So, super-duper wide rims give you the stoke. Good to hear that, it helps others who are struggling with the decision to invest. But 29er trail bikes made a lot of mountain bikers happy when they got popular, too, and even though the converts jumped on the interweb to excitedly proclaim big wheels were a GAME CHANGER, and used phrases like "bottom line" and "end of story," just like you are now, the truth was much more nuanced: some people preferred smaller wheels, and there are demonstrable, performance related reasons why one would have such a preference. Just like there are demonstrable reasons why certain riders would hesitate to adopt giant rims for their DH or enduro bikes with today's tire offerings. A lot of them are sticking with 25mm-29mm inner width for a reason.

Perhaps the overall trend will be towards big rims, or maybe it will be like the big wheel thing and it will settle into preferences, or maybe it's just another cycle of experimentation like the one that happened 10 years ago (yes, wide rims have been GAME CHANGERS before, too). Either way, you're dropping the mic a little too early.


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## Shredman69 (Apr 1, 2007)

oldranger said:


> Hi Folks,
> OP here..just saying hi again. I still am subscribed to the thread and always look forward to seeing where the discussion goes. (Still regretting I didn't put 'Downhill' in the Thread Subject, BTW)
> 
> Here's where I still stand for 2015 downhill riding/racing: I'm going in to a second year with the DT Swiss FR600 (inner 25mm, outer 32mm). I'm also still going to run 2.5" width Maxxis tires for dry or mixed conditions. Most often this will be the Minion DHF and DHR2 (3c). On rare occasion, there are conditions where I use the High Roller 2.5" 60a in the rear. For mud I use Continental Mud King 2.3 with the center lugs cut just a bit. These tires/rims match very well and the tire flexes predictably on the DT FR600 when I have proper pressures. I run tubeless in the front, with relatively low pressures and no burping problems. I use a Welterweight tube in the rear, and I did not have any pinch flats on the rear tire during the 5 or 6 races I competed in last year. From my perspective this spec is working well for me, and from a race results standpoint I achieved what I was hoping for. Note: I am rebuilding the rear wheel for 2015; the FR600 is a bit soft and light for my 190 pound riding weight and style.
> ...


I would give Light Bikes, Derby or Ibis rims a try, they all make wide carbon rims. Light Bikes makes a DH specific rim and it's not a bad price for a carbon rim. As for tires try what you like and see how it is.:thumbsup:


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## JLF1200 (Sep 16, 2009)

I didn't think Derby and Ibis made a DH version of their wide carbon rims. Doesn't mean you can't ride "down-hill" on them. Just means nobody will be surprised if/when they explode. LB makes a heavier rim they call "DH," it's the same weight as some of the Derby offerings I think, and their rims explode regularly, but at least they're a cheaper experiment.

As for a competent 27.5" DH tire that is designed for an inner rim width outside of the 2xmm range... that doesn't exist to my knowledge.

[edit]
Another thing to consider is that these are mostly hookless designs. A rim manufacturer PM'd me and mentioned that typical DH tire pressures don't do so well on hookless rims. So if you're running in the 30-40psi range, something to watch out for.

(Yes, I understand that wide rims allow for lower pressure. Good DH riders need pressure. Nobody can execute a competitive run at these punter numbers I keep seeing on wide rim threads. The wheels wouldn't survive, and the riders might not either.)


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## Shredman69 (Apr 1, 2007)

JLF1200 said:


> You're coming in hot!
> 
> So, super-duper wide rims give you the stoke. Good to hear that, it helps others who are struggling with the decision to invest. But 29er trail bikes made a lot of mountain bikers happy when they got popular, too, and even though the converts jumped on the interweb to excitedly proclaim big wheels were a GAME CHANGER, and used phrases like "bottom line" and "end of story," just like you are now, the truth was much more nuanced: some people preferred smaller wheels, and there are demonstrable, performance related reasons why one would have such a preference. Just like there are demonstrable reasons why certain riders would hesitate to adopt giant rims for their DH or enduro bikes with today's tire offerings. A lot of them are sticking with 25mm-29mm inner width for a reason.
> 
> Perhaps the overall trend will be towards big rims, or maybe it will be like the big wheel thing and it will settle into preferences, or maybe it's just another cycle of experimentation like the one that happened 10 years ago (yes, wide rims have been GAME CHANGERS before, too). Either way, you're dropping the mic a little too early.


Hahahaha, dropping the mic a little early, that was funny. Just to be clear though, I don't follow trends. I still run 26" and I probably always will, I don't run super wide straight bars, mine are 700 wide with 40 rise, carbon. I run what works for me and and I don't run or keep stuff if its not an improvement. I don't change just because the industry or a magazine says its better unless, I've tried it and I agree. Anyway, as for wide carbon rims, try it for your yourself and I think you will agree, they are pretty f-ing awesome.


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## Deerhill (Dec 21, 2009)

oldranger said:


> Hi Folks,
> OP here..just saying hi again. I still am subscribed to the thread and always look forward to seeing where the discussion goes. (Still regretting I didn't put 'Downhill' in the Thread Subject, BTW)
> 
> Here's where I still stand for 2015 downhill riding/racing: I'm going in to a second year with the DT Swiss FR600 (inner 25mm, outer 32mm). I'm also still going to run 2.5" width Maxxis tires for dry or mixed conditions. Most often this will be the Minion DHF and DHR2 (3c). On rare occasion, there are conditions where I use the High Roller 2.5" 60a in the rear. For mud I use Continental Mud King 2.3 with the center lugs cut just a bit. These tires/rims match very well and the tire flexes predictably on the DT FR600 when I have proper pressures. I run tubeless in the front, with relatively low pressures and no burping problems. I use a Welterweight tube in the rear, and I did not have any pinch flats on the rear tire during the 5 or 6 races I competed in last year. From my perspective this spec is working well for me, and from a race results standpoint I achieved what I was hoping for. Note: I am rebuilding the rear wheel for 2015; the FR600 is a bit soft and light for my 190 pound riding weight and style.
> ...


I am still trying to find something in 650b that is like the 26 WTB Laserdisc (they were made pretty tough and resistant to dents.. Do you know if the DT FR 570 uses similar alloy as those FR 600 rims?

I still need to look into the Alex offerings also


----------



## Mountain Cycle Shawn (Jan 19, 2004)

Derby makes a HD carbon rim.


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## meltingfeather (May 3, 2007)

JLF1200 said:


> I didn't think Derby and Ibis made a DH version of their wide carbon rims. Doesn't mean you can't ride "down-hill" on them. Just means nobody will be surprised if/when they explode. LB makes a heavier rim they call "DH," it's the same weight as some of the Derby offerings I think, and their rims explode regularly, but at least they're a cheaper experiment.


I think the "DOWNHILL" Derby rims are probably meant for downhill.

What's "punter pressure" and how often is "regularly" when you're talking about the explosion of LB rims? Both seem on their face like smug, douchey comments, FWIW.


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## JLF1200 (Sep 16, 2009)

meltingfeather said:


> I think the "DOWNHILL" Derby rims are probably meant for downhill.


Sounds like a reasonable assumption, LOL. Thanks for doing the hard work of actually navigating to his website. :blush:



> What's "punter pressure" and how often is "regularly" when you're talking about the explosion of LB rims? Both seem on their face like smug, douchey comments, FWIW.


DISCLAIMER: I am still responding to the OP, wherein the context of DH riding and racing was referenced. (Maybe this should be a permanent disclaimer).

LB rims blow up more often than a DH staple like a Mavic 729. One might say "regularly." Sure, they're carbon, but that's not a common rim material to DH folks, so calling out their known explosivity in relation to alloy rims seemed appropriate. Is that smug and douchey? :???: Not sure why. Sorrynotsorry.

Punter pressure means "not enough." Pretty common to run 30psi-35psi on rowdy stuff. PSI in the teens would qualify as punter.

I guess it's not cool to use the word 'punter'? Meh. It's stolen from skiing, but it means the same thing: someone who doesn't know what they're doing. Low tire pressure, soft forks, stiff/underdamped shocks, etc. Punter. Ya know? Maybe you don't know. Either way, not sure why you're offended. Are you racing DH on tires inflated to 17psi?


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## meltingfeather (May 3, 2007)

JLF1200 said:


> Sounds like a reasonable assumption, LOL. Thanks for doing the hard work of actually navigating to his website. :blush:


:arf:



JLF1200 said:


> DISCLAIMER: I am still responding to the OP, wherein the context of DH riding and racing was referenced. (Maybe this should be a permanent disclaimer).
> 
> LB rims blow up more often than a DH staple like a Mavic 729. One might say "regularly." Sure, they're carbon, but that's not a common rim material to DH folks, so calling out their known explosivity in relation to alloy rims seemed appropriate. Is that smug and douchey? :???: Not sure why. Sorrynotsorry.


Well... I don't know how you know any of this... pretty sure you don't actually... so it's all speculation, which is douchey. The smugness is the part where you think you know something you don't and proclaim it as truth. 

I've seen DH riders trash rims... stout ass rims... more than any other kind of rider... more rims per rider all day long, so I'm not sure I even believe the premise that LB rims blow up more often than 729s.
LB doesn't even make make a "DH" rim... so you're comparing a beast DH aluminum rim to a carbon XC/trail rim?
"One might say 'regularly'?"
One might also say rarely... most of they people riding them would say *never*, since for the vast majority of users they have blown up zero times. Zero extrapolates to never in maths.



JLF1200 said:


> Punter pressure means "not enough." Pretty common to run 30psi-35psi on rowdy stuff. PSI in the teens would qualify as punter.
> 
> I guess it's not cool to use the word 'punter'? Meh. It's stolen from skiing, but it means the same thing: someone who doesn't know what they're doing. Low tire pressure, soft forks, stiff/underdamped shocks, etc. Punter. Ya know? Maybe you don't know. Either way, not sure why you're offended. Are you racing DH on tires inflated to 17psi?


Not offended... just clarifying. I kind of like the term, actually.
Not knowing what one is doing and doing something different than you (or even most people) is an important distinction, I think.
Anyway... not here for a pissing match at all. Carry on. :thumbsup:


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## JLF1200 (Sep 16, 2009)

meltingfeather said:


> Well... I don't know how you know any of this... pretty sure you don't actually... so it's all speculation, which is douchey. The smugness is the part where you think you know something you don't and proclaim it as truth.
> 
> I've seen DH riders trash rims... stout ass rims... more than any other kind of rider... more rims per rider all day long, so I'm not sure I even believe the premise that LB rims blow up more often than 729s.


Sigh. I've been doing this a while. A 729 is the cement truck of rims. Lacing it up with straight gauge spokes is the standard for 'indestructible'. It's what you ride if you DGAF about your times or if you're a hulking clyde or just sick of wrecking wheels... They're about 700g and you can basically beat them back into shape if you stack one up. In my shop(s) I've trued and bent so many 729s back from the dead it's hilarious. The LB rim threads are littered with angry people who swear they just looked at a rock funny and cracked their rims, and those aren't coming back. Actually, I think I've never been at a weekend race with*out* seeing detonated carbon wheels-- it happens "regularly," you might say.

I could certainly be biased due to the nature of the failures, however. Alloy rims failures are easy to miss. Carbon failure... is hard to miss. kaBOOM.

I'd also wouldn't be surprised if lab strength tests would favor carbon rims. Their stiffness might be the reason for real world failures. I'm just guessing there, obviously.

[edit]
I suppose it's also possible that carbon actually wears hits better than alloy and then fails suddenly, and in grander fashion. Either way, it's not uncommon for bruisers to run a 729 for years, with all kinds of battle scars. It's inconceivable to me that those guys could have carried a carbon wheel as far.



> LB doesn't even make make a "DH" rim... so you're comparing a beast DH aluminum rim to a carbon XC/trail rim?


I think the LB "DH" rims are probably meant for DH. 



> "One might say 'regularly'?"
> One might also say rarely... most of they people riding them would say *never*, since for the vast majority of users they have blown up zero times. Zero extrapolates to never in maths.


So how much exactly is "vast," when it comes to rim failure? I see what you're saying, though. LB rims might blow up, but not much in comparison to the LB rims that *don't* blow up. In fact, if we just ignore all the failures, it's pretty much a perfect record! :skep:



> Not offended... just clarifying. I kind of like the term, actually.
> Not knowing what one is doing and doing something different than you (or even most people) is an important distinction, I think.
> Anyway... not here for a pissing match at all. Carry on. :thumbsup:


Yes, well now you're veering into relativism. I can get behind that to a point. Jared Graves runs narrow bars (740mm) because he's doing it differently. A punter puts 17psi in his DH tires because he's doing it wrong.

And I do appreciate the jabs. Not trying to piss anywhere, either.


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## meltingfeather (May 3, 2007)

JLF1200 said:


> Sigh. I've been doing this a while.


You're not the only one.  


JLF1200 said:


> A 729 is[...]


I know what a 729 is... that was kind of my point.


JLF1200 said:


> The LB rim threads are littered with angry people who swear they just looked at a rock funny and cracked their rims, and those aren't coming back. Actually, I think I've never been at a weekend race with*out* seeing detonated carbon wheels-- it happens "regularly," you might say


There's reality and then there's rhetoric.
Not gonna split hairs over what "littered" means in a statistical sense, but if your gut feel from the threads you happen to have read is what you mean, that's what I figured and all I need to know.



JLF1200 said:


> I think the LB "DH" rims are probably meant for DH.


Touche... how does that happen?!? Gotta concede hilarity. :blush:



JLF1200 said:


> So how much exactly is "vast," when it comes to rim failure? I see what you're saying, though. LB rims might blow up, but not much in comparison to the LB rims that *don't* blow up. In fact, if we just ignore all the failures, it's pretty much a perfect record! :skep:


Not saying it is a perfect record... not saying I know... you said "regularly" and the fact is you don't know. One fact is that I've seen many more 729s flat spotted and out of true than LB rims. Does that mean anything? Nope... and neither does "regularly."
That's all I'm saying.



JLF1200 said:


> Yes, well now you're veering into relativism. I can get behind that to a point. Jared Graves runs narrow bars (740mm) because he's doing it differently. A punter puts 17psi in his DH tires because he's doing it wrong.


Would you say a punter *punts* 17psi in his DH tires? :arf:


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## JLF1200 (Sep 16, 2009)

After all that, I should add that I'm seriously considering building a set of LB DH wheels up, just in case I was giving the impression that I'm some sort of zealot. I'm not. However, I'm not doing it for the width, I'm more interested in the stiffness, especially in hard leans.


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## JLF1200 (Sep 16, 2009)

meltingfeather said:


> Not gonna split hairs over what "littered" means in a statistical sense, but if your gut feel from the threads you happen to have read is what you mean, that's what I figured and all I need to know.


I could restate it. My observations in real world racing scenarios seem consistent with my observations online: carbon mountain bike wheels crack, fail and blow up a fair amount. But (as I said before), there are possible sources of bias. Carbon fails spectacularly, alloy can do it quietly sometimes. And people get angry when their bling wheels detonate, which causes them to write angry forum posts. If you detonate a 729, well... there's probably a good story, and you're probably not writing a post about the rim.


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## ebenke (Sep 1, 2008)

JLF1200 said:


> I could restate it. My observations in real world racing scenarios seem consistent with my observations online: carbon mountain bike wheels crack, fail and blow up a fair amount. But (as I said before), there are possible sources of bias. Carbon fails spectacularly, alloy can do it quietly sometimes. And people get angry when their bling wheels detonate, which causes them to write angry forum posts. If you detonate a 729, well... there's probably a good story, and you're probably not writing a post about the rim.


Funny stuff man. Around here, everybody including racers are on or going to wider carbon hoops, 27.5, 29, whatever. Plain and simple, they are stiff. That's all.

EBenke


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## meltingfeather (May 3, 2007)

JLF1200 said:


> I could restate it.


Of course you can... but why?
I've seen many more taco'ed al rims than blown up carbon... I've also seen slow-fail carbon ridden for 15-20 miles or more to finish a race... it doesn't explode every time.
Different experiences... which is why experience is a poor basis for deciding how things always are. If that fact could be realized the server space that mtbr occupies would probably fit on a flash drive.


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## ebenke (Sep 1, 2008)

meltingfeather said:


> Of course you can... but why?
> I've seen many more taco'ed al rims than blown up carbon... I've also seen slow-fail carbon ridden for 15-20 miles or more to finish a race... it doesn't explode every time.
> Different experiences... which is why experience is a poor basis for deciding how things always are.


Same here. Currently carbon is winning in my book. Just last week my alloy seat stay on my STJ FSR snapped. Warranty is replacing it with carbon, and I like it!

EBenke


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## Shredman69 (Apr 1, 2007)

ebenke said:


> Same here. Currently carbon is winning in my book. Just last week my alloy seat stay on my STJ FSR snapped. Warranty is replacing it with carbon, and I like it!
> 
> EBenke


I'll add that I've never had or seen a carbon rim "explode" or even have a catastrophic failure. I cracked the rear of my first set of 33 wides, (it was an early version and it had regular hooked beads, the new ones are hookless and have thicker side walls where the tire bead rests and they are much stronger). It had been abused for months at Mammoth Bike Park, Snow Summit bike park and my local DH in So Cal. When it did crack, it made a pop sound and leaked a small amount of sealant. It still held air, was still true and I rode it six miles back to my truck and I stopped babying it after a mile or so. LB warrantied it and sent me a new hookless version, it cost me $40.00 for shipping from China to So Cal, cheaper than a new aluminum rim would have been. No problems with the next set of 33's or 38's since then.:cornut:


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## ebenke (Sep 1, 2008)

Shredman69 said:


> I'll add that I've never had or seen a carbon rim "explode" or even have a catastrophic failure. I cracked the rear of my first set of 33 wides, (it was an early version and it had regular hooked beads, the new ones are hookless and have thicker side walls where the tire bead rests and they are much stronger). It had been abused for months at Mammoth Bike Park, Snow Summit bike park and my local DH in So Cal. When it did crack, it made a pop sound and leaked a small amount of sealant. It still held air, was still true and I rode it six miles back to my truck and I stopped babying it after a mile or so. LB warrantied it and sent me a new hookless version, it cost me $40.00 for shipping from China to So Cal, cheaper than a new aluminum rim would have been. No problems with the next set of 33's or 38's since then.:cornut:


Did you get your wheels from Cyclogical?

EBenke


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## Shredman69 (Apr 1, 2007)

ebenke said:


> Did you get your wheels from Cyclogical?
> 
> EBenke


No, I got the rims directly from LB. I already had Hope Pro 2 EVO's from my old wheelsets. My LBS laced them up to DT Super Comps and aluminum nipples.:thumbsup:


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## oldranger (Apr 14, 2011)

Would one of the proponents of wide DH rims please take a few pictures of your bike and post it? Also please specify the inner width of the rim. I'm curious, because I just don't see these kind of things at the places I ride. It would also be awesome to know if you are a sponsored rider.


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## meltingfeather (May 3, 2007)

oldranger said:


> Would one of the proponents of wide DH rims please take a few pictures of your bike and post it? Also please specify the inner width of the rim. I'm curious, because I just don't see these kind of things at the places I ride. It would also be awesome to know if you are a sponsored rider.


Not a proponent and not my bike, but here's one if you can look past the wheel diameter:
(inner width 27.5mm, conveniently  )


I'm sure you know the FR600 (you might be able to say how many DH World Cups have been won on this rim... I don't know), which has an internal width of 26.5mm (not crazy wide, but above the ideal range according to you):


Here's the >30mm internal LB rims, just cuz this Banshee is sick:


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## Shredman69 (Apr 1, 2007)

oldranger said:


> Would one of the proponents of wide DH rims please take a few pictures of your bike and post it? Also please specify the inner width of the rim. I'm curious, because I just don't see these kind of things at the places I ride. It would also be awesome to know if you are a sponsored rider.


Here are a few of mine. The 33 wide are 27 internal and my 38's are 32 inside. My wife sponsor's me.


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## Salespunk (Sep 15, 2005)

JLF1200 said:


> Sounds like a reasonable assumption, LOL. Thanks for doing the hard work of actually navigating to his website. :blush:
> 
> DISCLAIMER: I am still responding to the OP, wherein the context of DH riding and racing was referenced. (Maybe this should be a permanent disclaimer).
> 
> LB rims blow up more often than a DH staple like a Mavic 729. One might say "regularly." Sure, they're carbon, but that's not a common rim material to DH folks, so calling out their known explosivity in relation to alloy rims seemed appropriate.


LB Rims have not held up well around here in Socal. Between three friends they have broken 11 rears in less than 12 months. None of them has broken a Derby yet. Definitely need to run higher pressures as the speeds go up especially on rocky courses. When racing I am running 25/30 in my Derby's and 21/27 for training. Even though carbon is tougher than aluminum, it is not indestructible.


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## Deerhill (Dec 21, 2009)

Anyone with Derby's or NOX or LB tried the 2.5" Magic Mary? I want to hear your thoughts on this 2.5" tread.. also is there another similar wide tire out there that is closer to matching this wider rim format? 27.5" 2.5" Magic Mary seems like the closest match to the wide carbon rims that I've found so far.


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## ColinL (Feb 9, 2012)

pharmaboy said:


> Seriously, one of the greatest certainties in this consumer world is that someone who bought something loves it, and recommends it - the only other option is for them to admit they made a mistake and were wrong ( in which case you'll notice they blame the manufacturer or someone else) . You may think that admitting mistakes comes easy, but look at your work colleagues etc - everyone loves their own decisions, hence *feedback from happy purchasers is pretty much useless.*


Yes, this is confirmation bias. But isn't no feedback at all the most useless?

Feedback from dissatisfied consumers is likewise colored. Perhaps even moreso... you can love a product and say little, but if you hate a product, in 2015 it seems much more likely that you'll tell the world about it. Vigorously.

So how do we make use of feedback? Trusted experts who are given equipment?

Unpaid reviews only go so far, because manufacturers aren't likely to give more equipment to someone who once gave them a bad review, and many sources of information which are somewhere between blogs, forums and traditional media lack the funds to buy their own equipment to review.

The best we can hope for on MTBR is everyone to share what they have, what they ride, where, how fast, and what they thought of the new equipment.

We can then figure out on our own if the poster is someone whose opinion we would trust a little, a lot, or not at all.


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## beanbag (Nov 20, 2005)

I just randomly poked my head in here again, and I see that civil discourse has broken out, LOL.


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## JLF1200 (Sep 16, 2009)

> I just randomly poked my head in here again, and I see that civil discourse has broken out, LOL.


That's because Craig went back to whatever wheel size debate he normally trolls and we started discussing wide, carbon rims again.


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## Guest (Jan 10, 2015)

JLF1200 said:


> That's because Craig went back to whatever wheel size debate he normally trolls and we started discussing wide, carbon rims again.


Proving once again that you're the king of civil discourse.

Actually, I find your opinions so ignorant that I don't feel exposing them as such is of any service. It appears you aren't aware that others are engaging you in the same way. You're an ignorant groupie, nothing more.


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## JLF1200 (Sep 16, 2009)

I love you too, Craig. Good to see you're still lurking in the shadows. 

Shredman, can you maybe send some tire profile pics of your 38mm wide wheels, and list the tire mounted as well? 

We've been using the term "wide" to describe everything from 25mm to 32mm inner widths. My own concerns are with widths out of the 2xmm range (Derby and the newer LB).


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## Shredman69 (Apr 1, 2007)

These are Intense Edge 2.5's and they are huge, fairly light and have a good profile. I also have some Schwalbe Magic Mary's waiting to go on as well as some Minion DHF 2.5's. I run these with 22psi front and 28 in the rear. With that psi, they feel rock hard like they have 40psi in them, because of the large volume.


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## Deerhill (Dec 21, 2009)

^^Schwalbe's with thicker/SG were like that too.. casing can pretty much hold the weight of the bike, 0 psi they look like they're aired up



Edit- This was on WTB laserdisc @ 26mm, i25 and DL31 @ 25mm


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## pharmaboy (Nov 11, 2005)

ColinL said:


> Yes, this is confirmation bias. But isn't no feedback at all the most useless?
> 
> Feedback from dissatisfied consumers is likewise colored. Perhaps even moreso... you can love a product and say little, but if you hate a product, in 2015 it seems much more likely that you'll tell the world about it. Vigorously.
> 
> ...


It's all useful ColinL, as long as you have put some thought into it, and can give posts the right weight in the decision making process. It's the dogmatic posters who unfortunately confuse the situation though.

The only thing that drew me to this thread was the significant number of people who had cracked carbon wide rims on rocks, and the association of that with running lower pressure than they did on normal alu rims. Those people have tended to blame the carbon rim quality/mold, when it really seems they are just running too low a pressure. If a few people read the discourse and then realise that there is a difference between setting pressure for burp prevention versus rim strike then that might save some rims from destruction.


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## Guest (Jan 10, 2015)

pharmaboy said:


> If a few people read the discourse and then realise that there is a difference between setting pressure for burp prevention versus rim strike then that might save some rims from destruction.


Isn't that the truth. I've seen some absurdly low psi claims attributed to wide rims recently (10 psi on a 2.5" tire!). My pressures are limited by rim strikes, wider rims don't help there.


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> Isn't that the truth. I've seen some absurdly low psi claims attributed to wide rims recently (10 psi on a 2.5" tire!). My pressures are limited by rim strikes, wider rims don't help there.


That's not true, a wider rim will help. In fact you can run lower pressures and get less rim strikes with a wider rim.


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## Shredman69 (Apr 1, 2007)

That is true, on my skinny aluminum rims, I had to run 35psi in the rear and 30 in the front to not get rim strikes/dings. With my wide carbon, 28psi in the rear and 22 front is all I need, and the tires, (regardless of brand) feel much harder with lower pressure and it's because of the larger air volume you get with wider rims.


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## Guest (Jan 11, 2015)

Mountain Cycle Shawn said:


> That's not true, a wider rim will help. In fact you can run lower pressures and get less rim strikes with a wider rim.


Explain how that can be.


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## Guest (Jan 11, 2015)

Shredman69 said:


> ...feel much harder with lower pressure and it's because of the larger air volume you get with wider rims.


Two questions:

1) How does larger air volume make something "feel much harder" despite having less pressure?

2) Why would "feel" affect whether rim strikes occur?

Bottoming out a shock on a given impact is a function of shock pressure, progressively, and shock travel. Same with a tire. Given that, how does a wider rim improve tire bottoming? Pressure is not increased (in fact, you are lowering it), progressively is not increased (it is lowered), and travel is not increased.


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## Shredman69 (Apr 1, 2007)

craigsj said:


> Two questions:
> 
> 1) How does larger air volume make something "feel much harder" despite having less pressure?
> 
> ...


I'm not an engineer, but I think because of the increased air volume, you have more air to cushion impacts. I think the main reason the tire feels harder is because the straighter, (verticle) sidewalls better support the tire, which leads to less rim strikes. But even with wide rims, you obviously can't run ridiculously low pressures especially for high speeds, without rim strikes.


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## oldranger (Apr 14, 2011)

From Enve: their current Downhill rim (M90 Ten, $999 for the rim) has a 25mm internal width. Based on opinion from Outside (online) this was one of the products that revolutionized cycling in 2014.

Still 25mm, just without the bead hooks.
Enve Composites M90 Ten Wheels - Reviews, Comparisons, Specs - Mountain Bike Wheelsets - Vital MTB


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## ebenke (Sep 1, 2008)

craigsj said:


> Explain how that can be.


x2. Sounds counter intuitive.

EBenke


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## oldranger (Apr 14, 2011)

One of the 'bleeding edge' DH Race bikes of 2015 has rims with a 24mm internal width. It seems to me, that the move from 26" diameter to 27.5" diameter would have been the optimal time to also evaluate the benefits of a wider rim. Do you think maybe the engineers at Specialized didn't think about it?

Price is clearly not a concern on a $9,000 bike.

Specialized Bicycle Components


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## ebenke (Sep 1, 2008)

oldranger said:


> Price is clearly not a concern on a $9,000 bike.
> 
> Specialized Bicycle Components


With Specialized price is always a concern. That's why they mix and match parts at all levels. I wouldn't put it past them.

EBenke


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> Explain how that can be.


Well, it's kinda hard to explain. It's not just the air volumn. I'm not really sure there is enough air volumn change, if any, to make a difference. It's because the force being applied to the tire will be going down the sidewall from the edge of the rim to the tread, more evenly. This is why slightly narrower tires work best with wider rims. The wider rim makes the sidwall more perpendicular to the ground. As opposed to a narrow rim, where you have the rim and tire making an egg shape, the force being applied to the tire would go through the sidewall at an angle and at a much thinner section of the sidewall because the sidewall is no longer perpendicular the the ground. Look at it this way: envision how easy it is to grab a light bulb by the fat part and break it off, when it is screwed into a light fixture. Now envision how harder it would be to break a light bulb off if the base was just as wide as the fat part. It could easily take two or three times more force to break the light bulb off. If the sidwall is now in a much stronger position, you can run lower pressures. If I remember correctly Derby recommends 10% of your ridding weight + or - one psi.

Another way to look at it. You can bench press more weight if your forearms are perpendicular to the ground and the bar, as opposed them being angled in towards the center of the bar. The arms are the sidewall in this example.


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## ebenke (Sep 1, 2008)

Mountain Cycle Shawn said:


> Well, it's kinda hard to explain. It's not just the air volumn. I'm not really sure there is enough air volumn change, if any, to make a difference. It's because the force being applied to the tire will be going down the sidewall from the edge of the rim to the tread, more evenly. This is why slightly narrower tires work best with wider rims. The wider rim makes the sidwall more perpendicular to the ground. As opposed to a narrow rim, where you have the rim and tire making an egg shape, the force being applied to the tire would go through the sidewall at an angle and at a much thinner section of the sidewall because the sidewall is no longer perpendicular the the ground. Look at it this way: envision how easy it is to grab a light bulb by the fat part and break it off, when it is screwed in to a light fixture. Now envision how harder it would be to break a light bulb off if the base was just as wide as the fat part. It could easily take two or three times more force to break the light bulb off.


Hmmm, might need a comparative diagram, a visual would be helpful.

EBenke


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## Shredman69 (Apr 1, 2007)

ebenke said:


> Hmmm, might need a comparative diagram, a visual would be helpful.
> 
> EBenke


Wide rim tire sidewalls | |

Narrow rim tire sidewalls / \


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## ebenke (Sep 1, 2008)

Thanks. I don't know though given lower pressures if this would still be the case however. 

A direct impact is going to cause the tire to deform, regardless.


EBenke


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## Mountain Cycle Shawn (Jan 19, 2004)

ebenke said:


> Hmmm, might need a comparative diagram, a visual would be helpful.
> 
> EBenke


I added another example above.


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## Mountain Cycle Shawn (Jan 19, 2004)

ebenke said:


> Thanks. I don't know though given lower pressures if this would still be the case however.
> 
> A direct impact is going to cause the tire to deform, regardless.
> 
> EBenke


It works.


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## Shredman69 (Apr 1, 2007)

ebenke said:


> Thanks. I don't know though given lower pressures if this would still be the case however.
> 
> A direct impact is going to cause the tire to deform, regardless.
> 
> EBenke


That's true, but it, (| |) won't distort as easily as (/ \). The more vertical sidewalls support the weight better.


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## Mountain Cycle Shawn (Jan 19, 2004)

Shredman69 said:


> That's true, but it, (| |) won't distort as easily as (/ \). The more vertical sidewalls support the weight better.


This is true!


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## Mountain Cycle Shawn (Jan 19, 2004)

I would suggest that you guys read:

WIDE rims

Technical Scroll down a little.


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## SS Hack (Jan 20, 2012)

Shredman69 said:


> Wide rim tire sidewalls | |
> 
> Narrow rim tire sidewalls / \


Perfect! I just mounted a 3.0 tire on a 19mm rim and pretty much got that shape - road in my yard only.


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> I would suggest that you guys read:
> 
> WIDE rims
> 
> Technical Scroll down a little.


Do you think Derby rims might have a bias to them?

Edit - on their picture the tyre is now 1/60th bigger. So maybe you can run 29.5psi rather than 30psi? Is that your lower pressure?

Just because something sounds sought of plausible doesn't make it true. Sidewalls have much importance in hysteresis and squirm, but if you have a square edge rock that has an area of 1 square inch as it contacts the tyre, 25psi is 25psi and the distance from outer tyre edge to rim is essentially the same whether it's 25psi or 20psi - but one will stand one fifth more force untill it hits the rim.

Go an do the experiment if you are so confident. Find a nice gutter, sit down on the rear wheel and ride into it with your narrow rims at 30psi - reduce the psi by 2 and keep repeating till you feel the clunk of rim contact. Now go get your super wide carbon rim with the same sized tyre, drop the psi by 5 below your first contact and ride into the gutter again.

Video the experience, if you have derby rims, this might be useful, because if you do happen to crack the rim, you can blackmail them by saying you'll upload the experiment to mtbr if they don't send you a replacement lol.

I'll give you another thought, how much less pressure can you run on a fatbike without rim strikes? The reason for that is on that same gutter, that tyre will have twice the surface area of gutter edge to spread the load


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## Mountain Cycle Shawn (Jan 19, 2004)

Blah, blah , blah! I've spent some time on them and I know how they work. They are better in every way than narrow rims. Ray, the owner of Derby is a very upstanding and extremely honest person, with more experience then most of us put together. I have found that everything he has written or said is the truth. It soulds like to me, you're spending to much time in the gutter.


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## pharmaboy (Nov 11, 2005)

I am not questioning an individuals honesty. There's a billion or 2 people in this world who think the earths only 4 thousand years old - their heartfelt belief doesn't make it true though


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> The only thing that drew me to this thread was the significant number of people who had cracked carbon wide rims on rocks, and the association of that with running lower pressure than they did on normal alu rims.


What rims? And, were they hookless rims. I know one thing for a fact, they weren't Derby rims, which are hookless. The only other wide rim I would consider buying would be the Ibis rims.


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> Do you think Derby rims might have a bias to them?





pharmaboy said:


> I am not questioning an individuals honesty.


What do you think the above statement implies? Dude, you need to shut your **** up, stop trolling here and go try a set. You sound like those stupid idiots that wouldn't shut up about how disc brakes wouldn't work when they first came along.


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## Yody (Jan 21, 2008)

Mountain Cycle Shawn said:


> Blah, blah , blah! I've spent some time on them and I know how they work. They are better in every way than narrow rims. Ray, the owner of Derby is a very upstanding and extremely honest person, with more experience then most of us put together. I have found that everything he has written or said is the truth. It soulds like to me, you're spending to much time in the gutter.


Sometimes guys can really be smart on paper when it comes to mountain biking, but not fast enough/capable/skilled enough to really get past the engineering hype and get real feedback from riding. I've ridden with Ray...very nice gentleman..and really into bikes and engineering.


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## Ridnparadise (Dec 14, 2007)

Mountain Cycle Shawn said:


> What do you think the above statement implies? Dude, you need to shut your **** up, stop trolling here and go try a set. You sound like those stupid idiots that wouldn't shut up about how disc brakes wouldn't work when they first came along.


No point getting frustrated. He's not a troll and there's no harm in asking questions. Most people who have gone to wide carbon rims went from narrow metal ones, so of course it will feel different and better. Not many have gone from narrow to wide carbon - maybe they have at Derby. If so there may be some available experimental evidence comparing distortion, squirm and rim impact.

There are a lot of factors in choosing a rim, not least being the widest option possible for your frame and whether a more "vertical" tyre on a narrow rim would suit better than a "flatter" or rounder profile on a wider rim. ie would a 26" with lower lateral forces at the rim be better with a narrow rim when a bigger wheel may be able to sacrifice more diameter to chase less distortion etc etc


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> What do you think the above statement implies? Dude, you need to shut your **** up, stop trolling here and go try a set. You sound like those stupid idiots that wouldn't shut up about how disc brakes wouldn't work when they first came along.


Relax man. The Giant dealer thinks his **** is the best and so does the Santa Cruz guy. I don't take any bodies word for it when they are peddling their wares - they luv their stuff and are biased - it goes with the territory of selling stuff.

You're holding on way too tight - nobodies going to die here on the width of their rim


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## manitou2200 (Apr 28, 2006)

I've been following this thread as I have an interest in what's discussed here. I have to say it's gotten a bit hostile and that's not really necessary but good points have been made. I'll give you my take. I've been running I9 enduro wheels 28/23.5mm for 7 years 26" and 29" as well as 36mm OD/ 30mm ID DH rims for 4 years, all tubeless, on a variety of bikes from 5-7" and tires from 2.25-2.5". This spring I bought some Roval Fattie SL's, I'm an industry guy so I get pro deals and at the price I figured I'd try them out. My findings are all seat of the pants as well as comparisons with common riding partners. I don't race timed events but we do ride aggressively and are constantly pushing each other.

I bought the fatties for my Spider 29 and Spider Comp which I am building now. I've found I can run lower air pressure with better traction, handling and speed in cornering with my wider rims. Ive had rim strikes and cut tires with all of them flirting with the raged edge of traction trying to find the balance between dirt and rock for the terrain I mostly ride. I've found I can ride 3-5 psi less with the 30mm vs 24mm ID rims and have more control with the exact same tires. It wasn't until I spaced out checking air pressure this November on a cold morning ride that I finally had a rim strike with the Fatties at 15 psi.....dough!!! I cut the tire, booted and tubed it to finish the ride and the trip. 

In summary; I find that I prefer the 30ish ID rim vs the 24ish ID rim with the tires I ride. I like how the tires act on the wider rim, the ability to run lower air pressures, better traction and the more predictable steering as a result. JMHO!


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> flirting with the raged edge of traction trying to find the balance between dirt and rock for the terrain I mostly ride.


I think this is very important. Obviously, every tire, rim and rider combo has a limit as far as tire pressures goes. You gotta find that limit and not cross it.


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## Mountain Cycle Shawn (Jan 19, 2004)

Mountain Cycle Shawn said:


> What rims? And, were they hookless rims? I know one thing for a fact, they weren't Derby rims, which are hookless. The only other wide rim I would consider buying would be the Ibis rims.





pharmaboy said:


> Relax man. The Giant dealer thinks his **** is the best and so does the Santa Cruz guy. I don't take any bodies word for it when they are peddling their wares - they luv their stuff and are biased - it goes with the territory of selling stuff.
> 
> You're holding on way too tight - nobodies going to die here on the width of their rim


Just answer the questions?


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> Just answer the questions?


Well, nobody expected the Spanish Inquisition.

Perhaps, you could answer what your relationship is with Derby rims? Are you neutral, or not?

Wide, light 29" rim? Cracked carbon content... « Singletrack Forum

For instance. So I in that it's only beaded rims that crack? Given the only 2 cracked ones I've seen in the flesh, one was hookless and the other I don't know, I have reasonable suspicion that it's also a marketing dept bit of hype - perhaps because they break, they need to be hookless?

So, what's your relationship to derby?


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> Well, nobody expected the Spanish Inquisition.
> 
> Perhaps, you could answer what your relationship is with Derby rims? Are you neutral, or not?
> 
> ...


No relationship at all. But, I have picked his brain about wide rims. After spending a few hours on a set, I'm going to have my own set built. His rims aren't cheap garbage, like some of the other rims out there. Hookless rims are stronger. And out of the thousands of sets sold, to my knowledge there has only been one failure.


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## ThomasF (Oct 4, 2013)

mtnzj said:


> Don't forget these guys have to run their sponsor's equipment, and many of the mainstream manufacturers have not gone to the wider rims (partially due to old rim safety specifications).
> 
> Additionally, the world's top pro riders would kick ass on most any bike/setup you stick under them.


truth. i'm pretty sure aaron gwin could beat me down a hill riding a huffy.


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## Guest (Jan 12, 2015)

Shredman69 said:


> I think because of the increased air volume, you have more air to cushion impacts.


It works opposite of that, though that is commonly believed. More air means the tire will be less progressive when you need it to be more progressive. Fact is, though, that tires have no progressively at all.

More air would be helpful if you got it through more internal height. Wider rims don't do that though, they only increase width.



Shredman69 said:


> I think the main reason the tire feels harder is because the straighter, (verticle) sidewalls better support the tire, which leads to less rim strikes.


OK, I was thinking you meant "feel" differently. That would be tire-specific.



Shredman69 said:


> But even with wide rims, you obviously can't run ridiculously low pressures especially for high speeds, without rim strikes.


Yes, absolutely. I've seen quotes of 10 psi for a 2.5 tire on a 50mm rim and even 12-14 psi on a sub-2" tire on a 50mm rim so basic common sense alludes some riders.


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## Guest (Jan 12, 2015)

Mountain Cycle Shawn said:


> It's not just the air volumn. I'm not really sure there is enough air volumn change, if any, to make a difference.


Yeah, air volume cannot make any difference. The changes are small and in the wrong direction.



Mountain Cycle Shawn said:


> It's because the force being applied to the tire will be going down the sidewall from the edge of the rim to the tread, more evenly....


Yes, I don't have a problem with any of this explanation, it's just that the magnitude of the differences need to be compared to the magnitude of the forces involved.

Many bicycle tire sidewalls have very little structure and are essentially balloons. There is no doubt that the effective spring rate can change by stiffening the sidewalls through better rim support, the question is by how much?

To be clear, I like wider rims as much as anyone, I just feel that the benefit is in areas other than rim strike reduction. Tires can be made (and are) to benefit from rim width like you describe but they will be heavier and roll more poorly.


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## Guest (Jan 12, 2015)

pharmaboy said:


> Do you think Derby rims might have a bias to them?
> 
> Edit - on their picture the tyre is now 1/60th bigger. So maybe you can run 29.5psi rather than 30psi? Is that your lower pressure?
> 
> ...


Agree with this. Also, the fat bike tire has a lot more internal casing height to compress before a rim strike occurs.

Also there's a difference between avoiding rim strikes and surviving them. Hookless rims stand up to abuse better but they don't reduce strikes at all.


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## oldranger (Apr 14, 2011)

Mountain Cycle Shawn said:


> I would suggest that you guys read:
> 
> WIDE rims
> 
> ...Scroll down a little.


I did. There is some interesting content on there and many pictures of high end trail bikes. Here are a few things I found:


There is a mention of this MTBR Forum on the derbyrims.com 'About Us' page. 
There is also an explanation of the history behind the 'Derby' name - and it happens to be a type of riding (a derby) that is polar opposite of DH racing.
According to content on their 'Technical' page: they make a DH rim by adding carbon-fiber layering inside the hollow "double wall" rims.

There is no other substantial content related to downhill riding or racing on their website that I could find.

Now my conclusion from that read: The content on Derbyrims.com points to their products being a good fit for trail riding where the rider wants "_lower tire pressure when desired for less rolling resistance over rough terrain_", and of course if you ride derbies.


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## meltingfeather (May 3, 2007)

oldranger said:


> I did. There is some interesting content on there and many pictures of high end trail bikes. Here are a few things I found:
> 
> 
> There is a mention of this MTBR Forum on the derbyrims.com 'About Us' page.
> ...


This is _almost_ as clearly biased and nonsensical as the OP. Keep trying... you'll get there again. ut:


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## Mountain Cycle Shawn (Jan 19, 2004)

meltingfeather said:


> This is _almost_ as clearly biased and nonsensical as the OP. Keep trying... you'll get there again. ut:


Some people aren't smart enough to put two and two together.



oldranger said:


> I did. There is some interesting content on there and many pictures of high end trail bikes. Here are a few things I found:
> 
> 
> There is a mention of this MTBR Forum on the derbyrims.com 'About Us' page.
> ...


They sell DH specific lay ups. So everything explained there also pertains to DH rims There is also info there that explains some of the misconceptions in this thread, which pertain to all types of mountain bike riding.


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## oldranger (Apr 14, 2011)

For the sake of the quietly reading majority that are really trying to get some good advice before they drop some $$ on wide rims:

I've never seen Derby Rims on anyone's DH race bike. No contributor on this thread (that has a full fledged DH race bike) uses Derby Rims competitively at a Cat1 or Pro level. In 2014 I spent time at Whistler, Snowshoe, Plattekill, Beech Mtn for USAC GRT, and out on quite a few trails in the SC/WNC area. While the I9's are common...I've never seen one of the Derby Rims. So my personal observations are consistent with what you might find DH race teams using. (Not Derby, and generally speaking - not carbon rims...except the Syndicate)

Given that I'm not very smart...maybe one of you can show me a picture of a downhill bike with these rims.

P.S. Not you melted feather...you're the one that posts pics of bikes that you don't ride, and you also provideded incorrect information on the inner width of a DT Swiss FR600. It is 25mm (http://www.dtswiss.com/Resources/Support/Tech-Specs/Techspecs_RIMS_MTB_2015.pdf). Do you even have a DH bike?


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## JLF1200 (Sep 16, 2009)

> Do you even have a DH bike?


bingo.


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## pharmaboy (Nov 11, 2005)

Thought that perhaps some readers might find this post below useful. Bholwell is a tyre designer and ex maxxis tyre designer, to me, that seems to be about the top of the tree as far respectability and experience goes.



bholwell said:


> For the theoretical change in carcass width and height as rim width increases, see the charts below. Note that this is for carcass width; tread width will change even less as you move to a wider rim. The profile will appear more 'square', however.
> 
> View attachment 862174
> View attachment 862175
> ...


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## J-Ha (Jul 21, 2010)

My Turner DHR equipped with Derby rims, I9 hubs and spokes:

Turner DHR by Oinkideas, on Flickr

Bike in action... for the sake of transparency, I will say that the following shots were taken before the new wheels were installed. They have been posted to indicate the use (rock gardens and road gaps) that the wheels will see.

Timberline Bike Park by Oinkideas, on Flickr


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## meltingfeather (May 3, 2007)

oldranger said:


> Do you even have a DH bike?


Do you even have a set of wide rims?

I have a moron detector that bats 1.000 and it's lit up like a Christmas tree. If you want to post such an inflammatory thread title with such a strong opinion, it might lend some credibility to have some basis for that opinion other than the fact that you see sponsored riders riding their sponsors' equipment.

I might not even disagree with your premise, but your "argument" is a flailing mess drizzled with that always killer combination of ignorance and smugness. :thumbsup:


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## JLF1200 (Sep 16, 2009)

> I have a moron detector that bats 1.000 and it's lit up like a Christmas tree.


Haha yes! I'm definitely re-using that.

But anyway I think it was a reasonable thing to ask, it's just unreasonable to ask it in a dickish manner. Only because I really think the way a downhiller rides is a little different than most other styles, and the shoulder of the tire becomes more critical for them.


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## oldranger (Apr 14, 2011)

JHa. Thanks for the post - I hope to see you out at Snowshoe some day. I look forward to hearing your impressions of how the rims are working.

Melting Feather and friends that continue to attack me personally: Please just walk away then. If I am stupid and dickish (as you have written), please just be the better man you think you are and ignore this thread. Regardless of how you feel about the title of the thread - you can't ignore the # of views and Replies. People are interested in this topic.


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> I know from personal experience that 'wide' rims feel different
> 
> I've ridden these rims on Freeride, DH Racing and DS:
> 
> ...





I'm kinda confused here, because I don't consider these to be wide rims.


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## ColinL (Feb 9, 2012)

It seems to me that Mavic, ENVE, etc have all the money it takes to do the research, and all the engineers to make whatever product they want. I think it is telling that when they moved up from 19mm ID, they did not go to 30mm ID, most of them are in the 24-25mm range even for DH. They have pros riding this stuff, and those pro teams want to win. They claim they don't use custom wheels, they use the regular stuff.

Anyone remember all the hype around the Velocity P35? And then remember all the tacoed wheels and spokes pulling through the rim? What a piece of crap that turned out to be. It turns out that you can't have a wide, light, strong, cheap rim. Who couldn't guessed that? 

To sum up:
I think established companies know the optimal width for rims based on tires, and vice versa for tires on rims. They all saw the sales that came from 29ers, and got on 27.5/650B much faster once it caught fire. They would move to wider rims if it helped.

..someone else probably mentioned this at some point in the past 16 pages, but it was lost in the drama and insults.


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## Mountain Cycle Shawn (Jan 19, 2004)

^ Who said rims have to be cheap. But, you can have wide, light and strong rims. And they work pretty well too!


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## oldranger (Apr 14, 2011)

OK, sorry for the confusion Mountain Cycle Shawn. I only listed the rims I have ridden on so that readers could know what experience I had; that seems relevant. I probably should have edited the OP for some clarity along the way, but felt it best not to.

I will distill my original post down to the two sentences I had *in bold *to try and simplify where I stand. It seems like my other information just caused confusion, but I was trying to show I had done some limited research before posting. Note: DH = Downhill

*So: I think it is all hype. My guess is that the ideal rim width for DH tires on the market today is 23mm - 25mm of internal width.*

Disclaimer: I am not the most coherent writer on this board and this original post from a year ago, was probably my third post on this board, maybe the first or second. I don't remember

Request as the OP: for those of you with 2,000+ posts can you please just stop picking apart my year old post and bashing me, and let me know if I've missed any interesting information like:

_- Maybe MTB tire manufacturers are now designing DH tires for rims with internal widths >25mm
- Maybe there is a race team that has chosen to use wide rim 'X'
- Maybe there is a racer out there kicking ass on some regional series that has improved their times noticeably just by getting wide rims_


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## ColinL (Feb 9, 2012)

oldranger said:


> _- Maybe MTB tire manufacturers are now designing DH tires for rims with internal widths >25mm_


This is possible. I am not aware of any limit on tire sizes, but one could exist somewhere in a UCI rulebook. I've seen DH tires that were rated as 2.7" and weren't actually quite that large, while some 2.4" tires are significantly bigger.

Obviously, the reason pros aren't taking 26x4 up the lifts is because there isn't just a question of traction, it's rolling resistance, handling and even weight as well, since high-level DH races usually do require some pedaling.


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## Brian Damage (Apr 15, 2007)

Pinkbike's take....
On today's Ask Pinkbike they were talking out tubeless & DH with some statements that are relavent to this discussion.

Disclaimer: I am a big fan of the 'ultra wide' rim (Derby etc), I'm not a DH racer, and I'm just relaying what I read on pinkbike

Ask Pinkbike: Correct Shock Length, Tubeless for Gravity, A-Line Paralysis Tips, and Keeping the Bits Out of Your Goggles - Pinkbike

"Few DH pros run tubes, so that is as good an indication as any that tubeless tires can corner hard and not burp air or pinch flat. Almost no enduro racers run tubes as well, but it is worth noting that both groups use wide rims (26 to 30mm inner widths) to stabilize the tires laterally."


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## oldranger (Apr 14, 2011)

Brian Damage said:


> Pinkbike's take...."Few DH pros run tubes, so that is as good an indication as any that tubeless tires can corner hard and not burp air or pinch flat. Almost no enduro racers run tubes as well, but it is worth noting that both groups use wide rims (26 to 30mm inner widths) to stabilize the tires laterally."


Thanks for the link. I haven't checked all the 2015 pro setups yet, but I do see that the Specialized team is killing it on some DT Swiss rims. You know what is interesting about that....they seem to be running the EX471 with an inner width of 25mm, not the FR570 that has an inner width of 27.5mm. They save about 100 grams with that...


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## ColinL (Feb 9, 2012)

The ENVE 27.5 rim that Bryceland won last year on is supposedly the stock 25mm ID rim that anyone can buy, the M90 DH: M90 Ten 27.5 - Wheel | ENVE

So, while I respect Pinkbike and I love their reviews, I'm a little uncertain as to the source and veracity of that link which is authored by 'Pinkbike Staff'.


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## dirtrider76 (Sep 19, 2012)

ColinL said:


> This is possible. I am not aware of any limit on tire sizes, but one could exist somewhere in a UCI rulebook. I've seen DH tires that were rated as 2.7" and weren't actually quite that large, while some 2.4" tires are significantly bigger.
> 
> Obviously, the reason pros aren't taking 26x4 up the lifts is because there isn't just a question of traction, it's rolling resistance, handling and even weight as well, since high-level DH races usually do require some pedaling.


TBH I have a few 2.4 and 2.5 tires that are as wide as 2.7's I have here. The only tires I have on hand that actually are HUGE is the way old school Gazallodi 3.0 DH tires.


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> OK, sorry for the confusion Mountain Cycle Shawn. I only listed the rims I have ridden on so that readers could know what experience I had; that seems relevant. I probably should have edited the OP for some clarity along the way, but felt it best not to.
> 
> I will distill my original post down to the two sentences I had *in bold *to try and simplify where I stand. It seems like my other information just caused confusion, but I was trying to show I had done some limited research before posting. Note: DH = Downhill
> 
> ...


Oh don't be sorry. I understand now. You have absolutely no experience on wide rims. That means zip zilch nada riding time on WIDE RIMS. Give it some time. Like all big changes in this industry, it just takes time for everyone to adapt. Especially when a big change like this requires something else to be changed, in order to get the best out of the first change. You follow that? And, I can tell you that one of the first makers has sold hundreds, if not thousands of wide carbon DH rims with only one failure. That's pretty good! Plus you don't have to be racing DH to expose these wide rims to those forces. This same company has sold thousands of sets of these rims, DH and lighter lay ups to people who are pounding the crap out of them. Probably exposing these rims to more punishment then pro DHers, because their skill level isn't as good, and still only one failure. ONE ****ING FAILURE!


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## meltingfeather (May 3, 2007)

ColinL said:


> The ENVE 27.5 rim that Bryceland won last year on is supposedly the stock 25mm ID rim that anyone can buy, the M90 DH: M90 Ten 27.5 - Wheel | ENVE
> 
> So, while I respect Pinkbike and I love their reviews, I'm a little uncertain as to the source and veracity of that link which is authored by 'Pinkbike Staff'.


It says 'PinkBike staff' at the top because each section is written by a different person.
Richard Cunningham (MTB Hall of Famer and former editor of MBA) wrote the section on DH tubeless.


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## meltingfeather (May 3, 2007)

Ropelato rides the 30mm Roval Fatties on his enduro bike.

He also rode a 29er Enduro at 2013 DH Worlds. Qualified 2nd on it.


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## dirtrider76 (Sep 19, 2012)

ColinL said:


> Anyone remember all the hype around the Velocity P35? And then remember all the tacoed wheels and spokes pulling through the rim? What a piece of crap that turned out to be. It turns out that you can't have a wide, light, strong, cheap rim. Who couldn't guessed that?


That's where the Blunt35 rims started from. They are pretty common place now. I have a set, they mount up tubeless awesome, take a beating without damage, no crack's if they get a hard rim strike. So it was a product that was refined for a better end product. I believe they now have the Blunt35, Blunt and Blunt SL that spawned from those rims and seem to be selling well. Who would have guessed that?


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## manitou2200 (Apr 28, 2006)

I can tell you guys that I really like the Roval SL Fatties. They are light, stiff and seem like very tough wheels/ rims. I've only had that one dumb-ass rim strike with them when I neglected to check and air them up after a big temp drop last November. I'll probably trash the tire because I'm not sure it'll hold tubeless even with a good boot but I can't even tell the rim struck rock. There is not a mark on the edge or sidewall of the rim. 

I'll wager that Specialized/ Roval will have a new SL Fattie DH wheel set this next year based on the success of the SL Fatties. 

I've talked with the guys at I9 and they are not yet convinced of the >26mm ID carbon rim trend yet. Their new hookless Pillar Carbon rims are 24mm ID and made for them by Reynolds. 

As mentioned earlier; time will tell on this fat trend and DH but it wasn't that long ago that 36mm OD/ 30ish ID DH rims were more the norm than narrower rims.


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## manitou2200 (Apr 28, 2006)

Im building a set of Dually rims with I9 Torch hubs for a 29+ set up on my FTW steel frame. The rims looks very nice and they should make for a nice wheel set although all the spoke calculators called for spokes 2mm too long for the hubs and Dually's. Then the DT spokes were mis-matched on the second shipment. Hopefully third times s charm!


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## pharmaboy (Nov 11, 2005)

ColinL said:


> The ENVE 27.5 rim that Bryceland won last year on is supposedly the stock 25mm ID rim that anyone can buy, the M90 DH: M90 Ten 27.5 - Wheel | ENVE
> 
> So, while I respect Pinkbike and I love their reviews, I'm a little uncertain as to the source and veracity of that link which is authored by 'Pinkbike Staff'.


Pinkbike is very opinion based on most matters - they have nailed themselves to both extra wide rims and extra wide bars early on. It's not exactly Nature or Scientific American


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> Oh don't be sorry. I understand now. You have absolutely no experience on wide rims. That means zip zilch nada riding time on WIDE RIMS. Give it some time. Like all big changes in this industry, it just takes time for everyone to adapt. Especially when a big change like this requires something else to be changed, in order to get the best out of the first change. You follow that? And, I can tell you that one of the first makers has sold hundreds, if not thousands of wide carbon DH rims with only one failure. That's pretty good! Plus you don't have to be racing DH to expose these wide rims to those forces. This same company has sold thousands of sets of these rims, DH and lighter lay ups to people who are pounding the crap out of them. Probably exposing these rims to more punishment then pro DHers, because their skill level isn't as good, and still only one failure. ONE ****ING FAILURE!


What is wrong with you?

Are you completely incapable of carrying out a civilised discussion?

There is so much wrong in your post I don't know where to start, so I won't even bother, but your hissy fits and personal attacks sure don't project a considered intelligent poster


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## oldranger (Apr 14, 2011)

manitou2200 said:


> I've talked with the guys at I9 and they are not yet convinced of the >26mm ID carbon rim trend yet. Their new hookless Pillar Carbon rims are 24mm ID and made for them by Reynolds.


Note: their Gravity Rims are very popular amongst the riders in the Southeast. They have a 28.5mm internal width and in the 26" diameter the rim weighs 530g. I just can't afford a set at $1,200-$1,400.

So...I have contacted them and will see if I can get some time with one of their folks to understand how they came up with 28.5 inner width. On their website they write: _"The added traction and support our 28.5mm internal width provides is an incredible upgrade from the industry standard 21mm."_

26\" Gravity


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## manitou2200 (Apr 28, 2006)

oldranger said:


> Note: their Gravity Rims are very popular amongst the riders in the Southeast. They have a 28.5mm internal width and in the 26" diameter the rim weighs 530g. I just can't afford a set at $1,200-$1,400.
> 
> So...I have contacted them and will see if I can get some time with one of their folks to understand how they came up with 28.5 inner width. On their website they write: _"The added traction and support our 28.5mm internal width provides is an incredible upgrade from the industry standard 21mm."_
> 
> 26\" Gravity


You are correct! I should have clarified that they are not yet convinced on the wide carbon rims.


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## mattbyke (Jan 14, 2015)

Belive. Live. It's the mtb dream. It's finally here. Big rubber. Wide rims. Tubeless. 
On my 6.5" big boy bike. And my steel SS. And my trusty road bike. 
Volume. Lower/less tread. Bigger footprint. Lower psi. 
I run pacenti tl28 and dl31. Great rims. Narrow by wide standards. But much wider than the pinner rims of the late 80's 90's. A noticeable difference!


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## oldranger (Apr 14, 2011)

*Pacenti*

Pacenti; that was a new one for me. Never heard of that company but they seem interesting. Nice MSRP at $80 - $90 per rim.

From their website:
_The Pacenti DL31 rim was orignially designed as an Enduro rim, but has proven much tougher than its weight might suggest. For the last 2 seasons the DL31 has been proven on the toughest DH tracks in Europe under several Pro teams; including winning the 2013 Scottish National DH title under Joe Connell. The DL31 has a tubeless friendly design, welded construction and stainless steel eyelets. The DL31 is a wide, light rim designed for hard core trail riding, Enduro racing and the most extreme levels of DH abuse.

DL31 Specifications:

* Size: ISO 559 - 26"
* Width: 31.0mm
* Inner bead width: 26mm
* Section Height: 20mm
* ERD: 538mm
* Weight: 522g
* Welded Construction_


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## Yody (Jan 21, 2008)

this picture sums up why I don't want wide rims. confirms my suspicions and riding experience that these are good for people who like to ride straight up and down, and don't lean. just like too wide of a motorcycle tire on a street bike makes the steering flat, vague, and lazy... until tire companies come up with something, I'll pass


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## ThomasF (Oct 4, 2013)

i'm guessing wide rim on the left? i feel like anything over 27mm is too much, then it blocks the tires and you can't lean the bike over.


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## ColinL (Feb 9, 2012)

Yody said:


> this picture sums up why I don't want wide rims. confirms my suspicions and riding experience that these are good for people who like to ride straight up and down, and don't lean. just like too wide of a motorcycle tire on a street bike makes the steering flat, vague, and lazy... until tire companies come up with something, I'll pass


Is there a shot looking at the profile of the tire, the curvature of the tread face?


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## Guest (Jan 15, 2015)

Yody said:


> this picture sums up why I don't want wide rims.


(1) You should not repost copyrighted images from one site on another. That image comes from this article.

(2) That image is suspicious. The rim on the left is (supposedly) 41mm wide and has a 58mm wide tire on it, yet it appears that we see the rim outside the sidewall. Whatever the white-ish lines on either side are, they are not the (Ibis) rim.

This picture tells us nothing other than that the tread doesn't get wider with wider rims (as some believe).

The article reads like a forum post, but here's an interesting quote:

_"...we did experience some issues when it came to tyre choice. The tyres that perform best with these rims are those with rounded profiles, Maxxis Minions DHF, Schwalbe Hans Dampfs, and Maxxis Shorty's all performed very well. However tyres with defined shoulder knobs or very square edges performed less so, with the breakaway point being moved to a shallower angle of lean and a resultant highly unpredictable handling. ..."​_So the tire in the picture is one that is claimed to work well, as does the Minion DHF. Curious considering the comments here. As for other tires working less well, duh. That has been true since the dawn of time.

Find evidence that wide rims make all tires perform poorly and you might have something.


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## ColinL (Feb 9, 2012)

craigsj said:


> (2) That image is suspicious. The rim on the left is (supposedly) 41mm wide and has a 58mm wide tire on it, yet it appears that we see the rim outside the sidewall. Whatever the white-ish lines on either side are, they are not the (Ibis) rim.


:lol: Suspicious?

The white-ish lines are part of the sidewall of the tire. Look at the next image down. See the sidewall there, with the cross-hatched pattern? That's the reinforced part of the carcass that is intended to protect against cuts and give stability.

It's not visible in the pic on the 23mm rim because it's actually on the sidewall. The 35mm rim is stretching the tire profile enough that the sidewall is much nearer to ground.


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## mattbyke (Jan 14, 2015)

The Pacenti rims were a treat to build up. I love that they have eyelets. The tubeless bead is excellent . With tires snapping into the seat reassuringly with a commpressor. And no obnoxious graphics.


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## oldranger (Apr 14, 2011)

Another relevant comment from the article/review of those wide Ibis rims: 

"Riding in Scotland we could not find any mud tyres that suited the wheels, most common spikes have a narrow tread profile and look like a Mohawk on the burly Ibis rims. "

DH racers should really have a set mud tires. So if you go Ibis wide, be prepared to have another wheel set to support your wet conditions racing. Based on your mud tire of choice, it is possible you will have problems getting that tire to mount and give you the shape you need. I can't imagine seeing my Continental Mud Kings mounted up on these.


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## Yody (Jan 21, 2008)

I've ridden the derbys with minions, same thing, outside knobs point upwards, I don't like the feeling when leaning over far, when you expect the tire to start pushing and drift it just kinda rolls over the knobs and just feels like its gonna tuck, instead of holding on and drifting. That picture shows exactly what I thought was happening. I'm not here to try and win the mtbr online argument. I'm just relaying my experience and opinion. Buy whatever you want I don't give a crap.


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## Yody (Jan 21, 2008)

My buddy has those Pacenti's, they are very light, and soft. Dent very easily


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## mattbyke (Jan 14, 2015)

With big tires , I have not dented these. I use 2.4 chunkey monkey on front and smorgashbord on the rear. 18 and 20 psi . Tubeless. On a full rigid SS.


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## Yody (Jan 21, 2008)

Lol, Shredman says I'm clueless on my reputation sheet. LOL socal Fred has some nerve, I'd ride circles around you with your fancy shiny fred bikes.


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## ColinL (Feb 9, 2012)

Shredman neg repped me as well. He probably went through neg repping anyone that didn't bow down and pay homage to wide rims... because obviously, intelligent discourse should be eliminated. One opinion to rule them all! :thumbsup:


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## oldranger (Apr 14, 2011)

I got a response from Pacenti on a message I sent them. *Note upfront that Pacenti DL 31 rims have a 26mm inner width and therefore are not considered 'wide' in the context of this discussion.*

I have an excellent first impression of this company. Kirk Pacenti (father of the 650b tire diameter for MTB) has the kind of resume we need contributing to this discussion. I haven't asked his permission to quote him, but I will paraphrase a couple things from his very prompt, thorough response to my question. I asked him: _"Hi, Do you offer 'wide' rims for DH use? I hear that today's 'wide' is more like 30mm inner width. But I see you've designed yours differently. I'm interested in your thoughts on the 26mm inner width and why that is best."_

Key points from his response:
1) Once you get over 26-27mm inner width, the tire starts to get very square and doesn't roll over in corners and turns as easily as it should
2) He designed the P35 and found the bike had so much traction you had to change your riding style. It was nearly impossible to break loose when you wanted them to.
3) He prefers a slightly narrower DH rim for real racing
4) They have pro DH teams racing the DL31

I think the DH riders/racers monitoring this thread will well understand the second point I paraphrased from Mr. Pacenti. Yody has already comments on this.

Yody - I can imagine those Pacenti Rims do dent easily. AT 530 grams they would be too light for me - I make mistakes and dent my relatively soft FR600s that weigh in at 600 grams. That said - the DL31 might be a really good race day option and they have a great price point.


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## Deerhill (Dec 21, 2009)

Yody said:


> My buddy has those Pacenti's, they are very light, and soft. Dent very easily


They're about the same as Flow in the dent dept imo. DL31 little easier to fix the half dents, have you compared the newer offerings from Alex or DT?


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## mattbyke (Jan 14, 2015)

I race my pacenti rims. I've also dented every rim I've used sooner or later. My crank brothers iodine wheels are the worst softest rims ever. 
I'm not DH ing though . Only Xc . So stuff lasts longer


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## manitou2200 (Apr 28, 2006)

I've found the higher volume tires like some of the Schwalbes and Maxxis still give me a slightly round profile on the Fatties. I used to really like the Nevegal in 2.5 on my 36mm OD wide 26" rims. I don't have any issues with cornering using Hans Damfs or Nobby Nics on the Fatties, the 2.4 Ardents would also work well. The choice of tires to match the rim width is very important to the overall performance of the combo.


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## jabrabu (Aug 2, 2010)

I'm a hype-believer. I ordered a set of Roval Traverse Fattie SL 29er wheels. Under 1600g with 30mm internal width and 6-degree hub engagement -- sounds pretty sweet to me.


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## ThomasF (Oct 4, 2013)

i feel that for some, wide tires are useful, i feel that for some tires, like the DHF that a wide tire wouldn't block it out too much, i rode some Roval Traverse SL Fattie 650B 142+ wheels, on an Sworks Enduro, and i didn't find any faults in them on the ride, i cornered hard on flat ground, i didn't use many berms on the trail ride for the demo. i didn't think there was anything special about them though, they felt similar to my 23mm wheels, only lighter and stronger. i didn't look at the tires and see if they had an odd shape, but on the trail the felt fine. i didn't find any limitation in cornering, but it was only a 30-45 minute ride, and it was all together a new bike.

It'd be cool to be able to throw on a pair of wide rims on my current bike, ride my favorite trails, and see if there is a noticeable difference. for free that is.


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## mattbyke (Jan 14, 2015)

Wider rims and large casing tires, make rigid SS riding quite nice. For this application I welcome the trend. But this doesn't mean I'll be swapping out the wheels on the other bikes .


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## Guest (Jan 16, 2015)

ColinL said:


> :lol: Suspicious?


Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.

Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.



ColinL said:


> Shredman neg repped me as well. He probably went through neg repping anyone that didn't bow down and pay homage to wide rims... because obviously, intelligent discourse should be eliminated. One opinion to rule them all! :thumbsup:


Intelligent discourse? 

The rep system is worthless and ineffective as is complaining about it in-thread. Simply don't participate.

Even more embarrassing is people who attach insults (_friends don't let friends Fred_) in their footer. It's clear who people are.


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## ColinL (Feb 9, 2012)

craigsj said:


> Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.
> 
> Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.


Actually, when I read your post with 'suspicious' I thought it was an interesting term to use because it seemed as if you believed the photo was taken with the tire on a different wheel. Not wrong, but suspicious. As in fake, or deceptive?

It's not fake, it probably hasn't been photoshopped, and the article does contain several pieces of information (pictures and text) that clearly express the opinion that wide rims are _not_ an improvement for some tires.


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## slowride454 (Jan 11, 2014)

Here are my experiences...not DH. I live in Wisconsin so mostly XC and some AM/TR. I was on a set of skinny rims and 29x2.1s and hated them. Then I went BIG with a set of P35s and Conti Trail King 2.4s. Traction for miles, but I had to re-dish the rear wheel for FD clearance and they rubbed by noodly fork like crazy. Switched to 29x2.2 and fixed the rubbing issues. The tires measured almost 2.4 on the wide rims though. I then switched to a 23mm internal rim and the 2.2 tires now feel much better, but I have to run higher pressures and they slide around much more. All of my experiences follow what was paraphrased above about the P35 rim and changing riding style.


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## Yody (Jan 21, 2008)

craigsj said:


> Yeah, suspicious. Of course the lines have to be part of the tire. I've never produced such a thing on the images I've taken of that same perspective. It's incumbent on the authors and photographers to produce information that informs, not misleads. The other 99 shots out of 100 would not look like that IMO.
> 
> Not sure what that photograph tells anyone once you factor out how peculiar one side looks. It's meaningless.
> 
> ...


I can call you herb instead of Fred if it makes you feel any better, lmao


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## Guest (Jan 16, 2015)

ColinL said:


> Actually, when I read your post with 'suspicious' I thought it was an interesting term to use because it seemed as if you believed the photo was taken with the tire on a different wheel. Not wrong, but suspicious. As in fake, or deceptive?
> 
> It's not fake, it probably hasn't been photoshopped, and the article does contain several pieces of information (pictures and text) that clearly express the opinion that wide rims are _not_ an improvement for some tires.


Yes as in fake or deceptive.

The article did express an opinion clearly, one that seemed no more informed than many forum posts, but the article was not posted here, only a single picture that looked suspicious. There is no reason to believe that picture supports any narrative and the article itself claims that pictured tire works well with the wide rim.


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## Guest (Jan 16, 2015)

Yody said:


> I can call you herb instead of Fred if it makes you feel any better, lmao


I would have to respect you in order to care what you called me.


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## Yody (Jan 21, 2008)

craigsj said:


> I would have to respect you in order to care what you called me.


The feeling is mutual then, because i have zero respect for armchair quarterback engineers who can't ride for **** but love to argue online about specs and millimeters and lazer beams and convince themselves that they are right because they win the internet. I bet you ride by yourself all the time because nobody wants to hear your techno babble the whole ride, lmao


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## OriginalDonk (Jul 8, 2009)

Well this is fun guys. Sounds like it's time for some back to back to back to back testing. Unfortunately most of us don't have the coin to drop on multiple wheelsets to put through the wringer. If only there were "people" with "relationships" with these "companies" that could ride competing "products" and share something approaching objective "comparisons." We could of course decide how relevant those comparisons for each of us. Not sure a 120 pound woman at Vital is gonna get the wheel to flex like a Clyde. If you ride with a unique style, unique terrain, or just consider yourself too damn unique, it'll be up to you to compare directly.

Let's start hammering on the editors/moderators of the MTBR, Pinkbike, Vital, and the Euro Mags to tackle this issue. I'm pretty damn impressed by the commitment demonstrated by John Schafer here at MTBR to compare POV cameras. Trying to run more than two wheels at once would unfortunately kick you out of the whole "bi-cycle" thing.


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## Yody (Jan 21, 2008)

Not back to back, but one weekend I rode a DH trail in Santa Cruz (short loops) 5 times on a new Ibis Demo HD3 with Derbies and Minions. (I've been running minions on and off for more than a few years so I know the feel of them). Then went back a week or so later and rode it again multiple times on my 26" HD with Minion front and 28MM wide rims (23 internal)

I definitely felt like the wider wheels/minions felt awesome until you get to the drift point, you know that feeling as you load up the tire into a decreasing turn, and as it gets tighter you go to load more and get the wheel to start pushing..... I didn't like the way it felt on the wide rims. Didn't give me confidence, it would just try and tuck the front end. As well the minion on rear felt like way too much tire and wouldn't break loose ever, didn't like that but thats kind of a different matter. Traction up and down was really good and the bike felt super planted. But really I want max performance where it really counts


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## meltingfeather (May 3, 2007)

Yody said:


> Not back to back, but one weekend I rode a DH trail in Santa Cruz (short loops) 5 times on a new Ibis Demo HD3 with Derbies and Minions. (I've been running minions on and off for more than a few years so I know the feel of them). Then went back a week or so later and rode it again multiple times on my 26" HD with Minion front and 28MM wide rims (23 internal)
> 
> I definitely felt like the wider wheels/minions felt awesome until you get to the drift point, you know that feeling as you load up the tire into a decreasing turn, and as it gets tighter you go to load more and get the wheel to start pushing..... I didn't like the way it felt on the wide rims. Didn't give me confidence, it would just try and tuck the front end. As well the minion on rear felt like way too much tire and wouldn't break loose ever, didn't like that but thats kind of a different matter. Traction up and down was really good and the bike felt super planted. But really I want max performance where it really counts


So it just sounds like it was a little different than you are used to... when at the same time comparing a different wheel size altogether (the HD3 is 650b, right?).


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## manitou2200 (Apr 28, 2006)

I'm kind of thinking that the reasons you stated about drift and lean angle are why most of us with wider rims are finding lower air pressures with wide rims compared to narrower rims feel better on the handling side of things. I think the tires need more squash with the lower air pressure to allow more lean angle and the lower pressure also creates a bigger footprint.


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## manitou2200 (Apr 28, 2006)

I have some I9 Enduros w/ Flow rims and the SL Fatties both currently mounted with 2.35 Nobby Nics. I'll try to take some photos this weekend and air them up to the to identical pressure before hand for comparison sakes. I'm still playing around with the fatties to find the ideal tire to use with them.


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## Guest (Jan 17, 2015)

OriginalDonk said:


> Let's start hammering on the editors/moderators of the MTBR, Pinkbike, Vital, and the Euro Mags to tackle this issue.


Wide rims will evolve much like larger wheel sizes did, only more rapidly, and if you want to understand the market reaction, just read up on the 5 stages of grief. A fun exercise is to identify the stages of certain posters here. 

One things for sure, reviews by the people you mention won't tell us anything. Read what howell has to say instead. Tire designers actually work with this stuff. The market will accept wider rims and tires will evolve, just like they always have.


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## oldranger (Apr 14, 2011)

craigsj said:


> Wide rims will evolve much like larger wheel sizes did, only more rapidly...Tire designers actually work with this stuff. The market will accept wider rims and tires will evolve, just like they always have.


Has anyone found information that indicates tires are evolving for these wider rims?

Craigsj, when do you think the tire manufacturers and Pro DH race teams will get caught up with the wide rims (> 28mm internal width) movement?


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## dirtrider76 (Sep 19, 2012)

28 internal isn't even a new thing, I had those 4 years ago.


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## HillDancer (Dec 10, 2012)

A tire's contact patch under load in dynamic operation does not resemble its unloaded static image. 

When applying steering input, the tire contact patch lags behind the vertical centerline of the wheel (pneumatic trail), and deviates to the inboard side of a turn. This deviation is called slip angle. The greater the slip angle, the more understeer is introduced. Understeer is mostly derived from the tire's tendency to continue in its original direction in deference to steering input. There are other factors involved, but for simplicity sake I'm focusing on the tire & rim role. For the same size tire & air pressure, increasing rim width shortens the contact patch and increases its width, contact area remains unchanged. The shorter the contact patch, the shorter the lag behind the wheel's vertical centerline. Relatively widening the rim, widens leverage for the tire sidewall, which stabilizes the tire laterally, and reduces contact patch deviation inboard to a turn, resulting in reduced slip angle. low slip angle inhibits understeer characteristics. Some riders in this thread consider understeer (drifting, push) to be a positive attribute. I prefer steering response and bike direction to closely match steering input. I find an appropriate width rim to perform as intended; not hype.


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## Yody (Jan 21, 2008)

oldranger said:


> Has anyone found information that indicates tires are evolving for these wider rims?
> 
> Craigsj, when do you think the tire manufacturers and Pro DH race teams will get caught up with the wide rims (> 28mm internal width) movement?


Lol, just because a bunch of weekend warriors like a new product that makes them feel better, does not mean that everyone else is gonna get "caught up with the movement".


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## ColinL (Feb 9, 2012)

HillDancer said:


> A tire's contact patch under load in dynamic operation does not resemble its unloaded static image.
> 
> When applying steering input, the tire contact patch lags behind the vertical centerline of the wheel (pneumatic trail), and deviates to the inboard side of a turn. This deviation is called slip angle. The greater the slip angle, the more understeer is introduced. Understeer is mostly derived from the tire's tendency to continue in its original direction in deference to steering input. There are other factors involved, but for simplicity sake I'm focusing on the tire & rim role. For the same size tire & air pressure, increasing rim width shortens the contact patch and increases its width, contact area remains unchanged. The shorter the contact patch, the shorter the lag behind the wheel's vertical centerline. Relatively widening the rim, widens leverage for the tire sidewall, which stabilizes the tire laterally, and reduces contact patch deviation inboard to a turn, resulting in reduced slip angle. low slip angle inhibits understeer characteristics. Some riders in this thread consider understeer (drifting, push) to be a positive attribute. I prefer steering response and bike direction to closely match steering input. I find an appropriate width rim to perform as intended; not hype.


Slip angle and steering! Haha. That could be a quote from various car handling books or forums.

MTBs are not cars. Problem #1 with your assumption that they act the same is that bicycles are leaned into turns at speed. Problem #2 is that MTB tires are designed to lean and have tread on the shoulder that only gets traction when the tire is leaned.

When you flatten the tread face of a MTB tire beyond what the tire designer intended, the shoulder knobs cannot be used as designed. Additionally, the profile of the tire is no longer as rounded, which supports the ability to transition smoothly from left, center and right of the tire.

This was all said many times in this thread, but no one else came in here quoting Skip Barber...


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## Guest (Jan 18, 2015)

Yody said:


> Lol, just because a bunch of weekend warriors like a new product that makes them feel better, does not mean that everyone else is gonna get "caught up with the movement".


Sounds like someone's afraid the bike daddy bought them isn't gonna be what the cool kids ride anymore. Lol.


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## Guest (Jan 18, 2015)

ColinL said:


> Slip angle and steering! Haha. That could be a quote from various car handling books or forums.


Agreed, but the most basic reason this does not apply you've overlooked.

A wider rim on MTB does not make the contact patch wider and shorter. MTB tires contact the ground through their tread and the tread doesn't widen just because the rim does. If the tire were a smoothie on a smooth surface then things would be different, knobs change things considerably.

People should go back to post #378 in this thread and read the bhowell quote. There's a lot of solid information there that is commonly misunderstood.


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## HillDancer (Dec 10, 2012)

craigsj said:


> ...A wider rim on MTB does not make the contact patch wider and shorter...People should go back to post #378 in this thread and read the bhowell quote...


Your reading comprehension is poor. Originally Posted by bholwell_ "As the internal width of the rim increases, the contact patch will become wider and shorter" 
_
A lugged bike wheel does not tip-toe through a corner.



ColinL said:


> ...no one else came in here quoting Skip Barber...


Neither did I, those are my words.


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## Yody (Jan 21, 2008)

Hilldancer and craigsj are probably the same person, trolls


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## Guest (Jan 18, 2015)

HillDancer said:


> Your reading comprehension is poor. Originally Posted by bholwell_ "As the internal width of the rim increases, the contact patch will become wider and shorter"
> _


A full quote is called for here, not a butchered one to mislead others:

_"As the internal width of the rim increases, the contact patch will become wider and shorter (assuming the inflation pressure and load is kept constant.) However if the shoulder lugs are already in contact with the ground, the contact patch cannot grow wider; instead it becomes more squared off, and the pressure distribution within the contact patch changes."​_This is not a demonstration of my reading comprehension either. bhowell and I agree because we both understand how it works, not because I've paraphrased what he has said.



HillDancer said:


> A lugged bike wheel does not tip-toe through a corner.


Congratulations on your deepity. You've shown that you're both an idiot _and_ an a-hole.


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## IPunchCholla (Dec 8, 2013)

craigsj said:


> A full quote is called for here, not a butchered one to mislead others:
> 
> _"As the internal width of the rim increases, the contact patch will become wider and shorter (assuming the inflation pressure and load is kept constant.) However if the shoulder lugs are already in contact with the ground, the contact patch cannot grow wider; instead it becomes more squared off, and the pressure distribution within the contact patch changes."​_This is not a demonstration of my reading comprehension either. bhowell and I agree because we both understand how it works, not because I've paraphrased what he has said.


Ok, I'm in the market for new wheels and am looking at wider rims. Mostly because I my pressures go lower without rim strikes but get too squirmy. So I have been following this thread with interest even though I would describe my riding as all mountain as opposed to downhill.

I understand that the claim is that contact patch doesn't get wider and shorter (relative to narrower rims) if the shoulder lugs are in contact with the ground. Does this mean both left and right shoulder lugs? In other words wheel is vertical? Or does it mean if any shoulder lugs (wheel is tilted)? Does the reference to the contact patch not growing wider mean relative to narrower rimmed tires or mean growing wider under the load of the turn? Just trying to understand. thanks.


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## mattwright999 (Jun 25, 2014)




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## Blatant (Apr 13, 2005)

I'm sure Craig can explain it to you in small words. He's the smartest person on MTBR. Now if folks would just stop quoting his responses, my ignore function would work properly.


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## oldranger (Apr 14, 2011)

I'm no engineer, but in my opinion, the picture mattwright999 just posted should be considered marketing hype. 

"The tire folds and can even jump out of the rim". 

Really? Wow, there is so much bad information. This is why I still fall back to: show me a pro race DH team that is going with wide rims >28mm internal width. Or show me a tire manufacturer that is redesigning tires intended for wider rims.

I was thinking about it again...the fact the Specialized DH Race team is using the DT Swiss EX471 for racing instead of the wider, heavier rims is yet another solid indicator of what is important. They could choose any rim they wanted from the DT lineup, and they don't choose the widest one.


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## IPunchCholla (Dec 8, 2013)

Specialized DH team choice is interesting in light of their enduro team riding 30mm internal width rims this last year.


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## aerius (Nov 20, 2010)

oldranger said:


> Really? Wow, there is so much bad information. This is why I still fall back to: show me a pro race DH team that is going with wide rims >28mm internal width. Or show me a tire manufacturer that is redesigning tires intended for wider rims.
> 
> I was thinking about it again...the fact the Specialized DH Race team is using the DT Swiss EX471 for racing instead of the wider, heavier rims is yet another solid indicator of what is important. They could choose any rim they wanted from the DT lineup, and they don't choose the widest one.


Funny that you mentioned Specialized, in theory at least, they have the capability to design their own tires to go with wider rims, should they choose to run them. Trek I'd think does as well since they run Bontrager, and both of them have the size, market clout, and vertical integration to go all in on wide rims & tires. For whatever reason, nether Trek nor Specialized has gotten on the wide rims & tires train yet.

On the other hand it looks like the Ibis Enduro team will be on wide carbon wheels for the upcoming season. Guess we'll find out how well they work when Anne-Caroline Chausson & the rest of the team gets some races on them this year. If ACC cleans up this year then I we can say there might be something to them, if she and Tracy Moseley end up splitting the series again, I'd say it's inconclusive at best.


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## ThomasF (Oct 4, 2013)

aerius said:


> Funny that you mentioned Specialized, in theory at least, they have the capability to design their own tires to go with wider rims, should they choose to run them. Trek I'd think does as well since they run Bontrager, and both of them have the size, market clout, and vertical integration to go all in on wide rims & tires. For whatever reason, nether Trek nor Specialized has gotten on the wide rims & tires train yet.
> 
> On the other hand it looks like the Ibis Enduro team will be on wide carbon wheels for the upcoming season. Guess we'll find out how well they work when Anne-Caroline Chausson & the rest of the team gets some races on them this year. If ACC cleans up this year then I we can say there might be something to them, if she and Tracy Moseley end up splitting the series again, I'd say it's inconclusive at best.


bro... roval.


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## Blatant (Apr 13, 2005)

Have you ever ridden a pro rider's bike? Most of them would be completely foreign to an average joe like me and, presumably, most MTBR users.

Which is a roundabout way of saying I don't base any cycling parts decisions on what professional teams are running. But I still run skinny-ish rims, too, so what do I know.


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## jonshonda (Apr 21, 2011)

Girl Fight!!


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## manitou2200 (Apr 28, 2006)

I'd say settle down a bit. We're only talking about wheels and rim width! Folks also need to ride all these wheels with wider rims before they make such strong statements for or against. I've got wheels with rim widths from 21-40mm and they all have a place in mountain biking. I'm not saying ditch your skinnier rims but I've also found that the wide rims have great purpose. 

Girl fights are fun too though!!


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## manitou2200 (Apr 28, 2006)

Wow I hope I wasn't a buzz kill here!!😬


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## blcman (Feb 1, 2007)

manitou2200 said:


> Wow I hope I wasn't a buzz kill here!!😬


That's what happens here when rational thinking and reasoning are introduced!


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## manitou2200 (Apr 28, 2006)

blcman said:


> That's what happens here when rational thinking and reasoning are introduced!


Haha! There was some very good discussion going on in this thread but also some butt hurt pissing matches which are never good!

I hope all those carrying on here can engage in constructive discussion. I know the op was referencing downhill but most of it also applies to all mountain riding which is a much larger group of riders.


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## slowride454 (Jan 11, 2014)

I might have to see how my Conti Trail King 29 x 2.4 look on a 15mm internal vs the P35s.


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## pharmaboy (Nov 11, 2005)

mattwright999 said:


> View attachment 956503


I'm with old ranger on this one - the picture above is drawn and is typical of an ad agencies drawing - competing red and green ( good versus bad)is a dead giveaway it's for marketing purposes. It may or may not be accurate, but it's source is biased and designed to tell a story in favour of wide.

That picture therefore is evidence for the "hype" posited at the start of the thread.


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## pharmaboy (Nov 11, 2005)

manitou2200 said:


> I'd say settle down a bit. We're only talking about wheels and rim width! Folks also need to ride all these wheels with wider rims before they make such strong statements for or against. I've got wheels with rim widths from 21-40mm and they all have a place in mountain biking. I'm not saying ditch your skinnier rims but I've also found that the wide rims have great purpose.
> 
> Girl fights are fun too though!!


I get what you are are saying, but first hand experience isn't all it's cracked up to be. People will defend what they have bought till the ends of the earth, and especially if they seem to know a vendor. : D

No idea how to test them empirically and reliably.

I think I'm a moderate on this one - I've read all I can find, and have been swayed by the professional design engineers on the subject. I think places like pinkbike are far from neutral ( or thoughtful) - though to be fair, I've seen behind the scenes in public relations versus journalism, and regrettably the smarter people are driving the marketing and can pull the wool over the eyes of a journalist with remarkable ease.

Anyway, I think there is an advantage to wider rims upto around 25mm


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## IPunchCholla (Dec 8, 2013)

pharmaboy said:


> I get what you are are saying, but first hand experience isn't all it's cracked up to be. People will defend what they have bought till the ends of the earth, and especially if they seem to know a vendor. : D
> 
> No idea how to test them empirically and reliably.
> 
> ...


Why do you call the limit at 25mm? Is that due to current tire design? Or something inherent in the width of the rim itself? I am asking because I am in the market for some new wheels and am trying to decide between 25mm and 30mm. I am more of an AM rider than DH, but I push speed through some steep, fast, chunky, singletrack. I am also not a racer and am relatively new to MTB (1.5 years riding) so I am not sure that at my skill level I would necessarily be able to tell the difference, At the same time, I don't want to get something that is actually going to decrease performance, so I have been following (most) of this debate with interest.

From what I can glean most of those favoring the not so wide rims (28mm and less?) do so because of the adverse affect on the tire profile that the wider rims have on high speed cornering performance. This seems to be an issue for people who are going DH speeds and happens because the tread closes up as the rim becomes wider changing the performance of the tire. Most find this change negative. A few positive, ay least when considering the ability to run lower pressures without tire squirm.

I noticed that at EWS Whistler at least, and I think for the whole series, the Specialized riders were on the 30mm interior Traverse Fatties and were on standard Slaughter and Butchers. Specialized's data from the bikeradar review indicates that 30mm interior rims have around 18-20% less deflection than a 23mm int rim and they state that they think the sweet spot right now in terms of wheel weight vs rim width is 30mm.

I guess I am wondering how application specific rim width is right now? Perhaps for those of us not going DH race speeds on the descents, a 30mm interior rim is perfectly fine, stabilizing the tire at lower PSI, allowing more traction through that PSI while avoiding squirm while at DH speeds the change in tire profile combined with the more aggressive lean angles is actually more detrimental to performance than any traction/rolling benefit gained while not cornering super aggressively.

Just trying put together a summary overview of this thread for myself.


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## oldranger (Apr 14, 2011)

More information from a late 2014 race on one of the most extreme downhill tracks ever conceived: Redbull Hardline.

Red Bull Hardline Dan Atherton

I put this in here so those readers that may not know how dramatically different Downhill racing is from XC or Enduro can get a glimpse of where the DH sport is heading. This is an extreme event for 10 of the top riders in the world.

2.4 - 2.5 width tires and conventional, aluminum DH rims seem to be the prevalent choice at a venue where it seemed 'anything goes'. The winner was riding on Easton Havoc rims, and the track builders were riding narrow, cut mud spike tires in dry, loose conditions. (Conti Mud King 2.4)


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## ThomasF (Oct 4, 2013)

i think 27mm is the limit. its wider, but not WIDE its been used by DT swiss for some time now, and on a 2.5 or 2.4 inch tire it'd still be perfectly useable for DH and FR. i think 25mm is good for any application. 

But idc too much. ride whatever you want to ride, you guys need to stop bickering. some people want to buy the $3,000 carbon wide rims, and others of us will settle with 1,100 dollar alloy rims that are just as strong, just as capable, and not as wide, but a little heavier.


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## Mountain Cycle Shawn (Jan 19, 2004)

You guys need to keep bickering. In fact kick some ass while you're at it!!


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## pharmaboy (Nov 11, 2005)

IPunchCholla said:


> Why do you call the limit at 25mm? Is that due to current tire design? Or something inherent in the width of the rim itself? f.


Yep, the 2 tyre designers on these forums talk about designed rim size and not moving too far away from that. Second, the manufacturers who have the ability and testing facilities aren't screaming off into 30mm widths. Advances in width have been incremental over the last couple of years, jumping straight up to 30 from 23 (current flows) seems a big leap of faith.


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## manitou2200 (Apr 28, 2006)

I can feel the added support of the wider 30mm rims of my Fatties on the high volume 2.35+ size tires. As compared to my I9 Enduro/ Flow 25mm wide rim wheels there isn't any loss in cornering or ability to lean the bike in the turns. 

I feel that for tires under 2.3"/ high volume casings type tires that the gains would not be there and for smaller casing tires it might be detrimental to the handling. I think it's very much tire size related and especially tire volume. Like comparing gen 1 High Roller 2.35 to a Hans Damf or 2.4 Ardent or 2.4 trail King. There is no comparison in casing volume or tread width, the HR while a good tire is no where near as big as the others.

On the other hand install a Surley Knard 3.0 on a 24/26mm wide rim and see how that performs. It's not happening that's for sure!

It's a matter of choice and matching tires and wheels. I get pro deals from pretty much all the manufactures so I'm able to try stuff out and see what I like. I sell off stuff I don't like and I'm not selling my SL Fatties. I'm also not selling my Flow rim Enduros either. I'll set them up for different conditions and riding types. I'm going to put heavier weight tires on my Enduros that I'll use when shuttling runs and use the lighter fat tires on the Fatties.


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## Guest (Jan 23, 2015)

pharmaboy said:


> Yep, the 2 tyre designers on these forums talk about designed rim size and not moving too far away from that. Second, the manufacturers who have the ability and testing facilities aren't screaming off into 30mm widths. Advances in width have been incremental over the last couple of years, jumping straight up to 30 from 23 (current flows) seems a big leap of faith.


Advances in width haven't been incremental, they've been dramatic, and "jumping straight up" wouldn't be a "big leap of faith", it would be naive. The language you use suggests manufacturers are worried about going too far; that's not what's happening here.

There's a whole lot more at play than just the objective facts of how a rim works yet these things are conveniently ignored by those who don't want their narratives spoiled. Designers _could_ optimize for wider rims but they'd like a large market of wide rim riders to sell to first. We ride bicycles, not rims.

If 80% of the market was 30+mm rims you can bet that tires would be designed to work well on them and people would laugh at narrow-rim riders. That's not a statement of superiority, it's just how things are. This is the case today with narrow rims and it has, until recently, been the case for juvenile wheel sizes. Progress isn't instantaneous.

The fact is, racers (who drive a large portion of the cycling market) will not leave performance on the table once it's staring them in the face. The problem with wider rims is that they are making tires work better than intended and that actually causes problems in certain cases. Racing will adapt. New technologies are usually NOT greeted with optimized complimentary technologies out of the gate. It takes time.


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## pharmaboy (Nov 11, 2005)

Sorry, Craig, I haven't been clear. When I say incremental, I'm not including small niche manufacturers in particular over the near term, but the big guys who have moved from 19 then to 21 and out to 23 over the last 4 years or so.

I agree we buy bikes and don't think manufacturers are being conservative because of worry, it's more likely simply engineer driven - there are plenty of smart people working in industrial design, frankly, a whole lot smarter and better trained than a few journalists that ride bikes.

That after all is what the original "hype" question is what it's all about - lots of emotional words and unprovable concepts


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## Guest (Jan 23, 2015)

pharmaboy said:


> Sorry, Craig, I haven't been clear. When I say incremental, I'm not including small niche manufacturers in particular over the near term, but the big guys who have moved from 19 then to 21 and out to 23 over the last 4 years or so.


Ah, yes that's true.

I find it very disappointing how seldom advances come from larger manufacturers.


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## OriginalDonk (Jul 8, 2009)

I'm really wondering if and when tire manufacturers are going to assume that there are going to be enough wide rim owners to buy wide rim optimized tires. Sounds like WTB may already be on that track given their open discussion on Pinkbike but I'm wondering if and when Maxxis and Schwalbe may go down that road. 

I always find Country-specific tax and duty situations to be really interesting. I'm seeing more and more 30+ internal rims used in the U.S. and Canada, presumably because they're easier to get over her with Ibis, Derby, NOX, etc. It seems like 90% of European and "Commonwealth" (Australia, New Zealand, South Africa, etc.) riders are rolling around on narrow Euro produced products given the tax and duty situation. They're just so much cheaper. Anybody can order Light Bicycle rims or bring some Derbies over but few seem to want to fight their way through customs and pay those duties. The wide rims available at lower costs in the U.S./Canada are at a large economic disadvantage in Europe. 

The U.S. and Canada are huge markets but I think a Euro wide rim champion (in addition to Syntace) may be needed before tire companies decide to invest in the effort to design wide-specific tires.


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## Jon Richard (Dec 20, 2011)

My LBS is lacing up a set of Derby's for me, going from Crest's the difference should be evident if it's tangible.

I have high hopes, but I ride trails, not a dedicated downhiller. I leaned forward in my seat when the discussion started toward differences in rim width exhibiting attributes that suggest, as most things mountain bike, it can be either a benefit or a detriment depending on rider and intended use.


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## pharmaboy (Nov 11, 2005)

OriginalDonk said:


> I'm really wondering if and when tire manufacturers are going to assume that there are going to be enough wide rim owners to buy wide rim optimized tires. Sounds like WTB may already be on that track given their open discussion on Pinkbike but I'm wondering if and when Maxxis and Schwalbe may go down that road.
> .


Be careful with wtb. Their tyres are their own system and mate well with wtb rims with their rubber rim strip, but don't play well with stans rim and rim strip - burp far easier than say schwalbe on stans.


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## manitou2200 (Apr 28, 2006)

I agree with Craig's statement, it takes a critical mass to progress and make changes. Tire manufacturers are not going to invest in design and tooling to make tires for rims that are just a relatively small portion of the market. 

I do believe that some of the bigger players will be making moves into this wider rim trend and tires will eventually follow. Specialized is not exactly a small company in the bike biz. You can bet if they see enough success with their Fatties then the tires for them will come as well as more DH specific rims and tires. 

I'll also add to this discussion that larger tires also equate to additional clearance on forks and bike frames. You can't change one thing without impacting another. We do ride bikes, they're not really that complex but the components need to be compatible to make the whole bike work. 

What pharmaboy says is true regarding wtb tires and Stan's rims. They really don't fit on Stans rims at all! WTB does not even recommend the combination of their tires on Stans rims.


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## oldranger (Apr 14, 2011)

Quick Update: I9 did not respond (in any way) to the question I posed to them via their website. So I have nothing to report back.


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## scottie mac (Nov 3, 2011)

My camber evo came equiped with Fattie ALs and I rode it one time that way before switching to my normal wheels - roval control carbons. I do feel the wider profile rim with Purgatorys front and rear did have a slight handling advantage over the narrow carbon controls. A buddy of mine who comes from the MX world, who is extremely in tune with his set ups, just purchased a pair of roval fattie carbon traverse wheels. He loves them. He also uses Purgatory tires on the front and we measured his tire profile and mine back to back. His tires were around 2.3mms wider than mine, matted, tubeless running his desired preasure (23psi). I typically run 24-25psi on mine. 

I think there is an ever so slight advantage to the fatties, but it isn't anything like going from a 2.0 tire to a 2.3. Having said that, as mentioned above, with advances in tire designs, I can only see the advantages in the handling department only getting better. I don't think they are going to be a manadatory upgrade for everyone, but for those who like to push the edge, espescially pointed down, I could see it. 

Just my opinion. 

Scottie


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## meltingfeather (May 3, 2007)

craigsj said:


> I find it very disappointing how seldom advances come from larger manufacturers.


I agree, though I also don't find it surprising. The bigger the mfr, the more the beureaucratic/administrative momentum is built into each move.
Now throwing money to an "edgy" sub-brand or "development" entity could be interesting, but most shareholders are looking for quarterly dividends and couldn't care less about anything other than performance.


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## jmcdev1 (Jan 1, 2011)

Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?
Planning to put a wheelset with some wider rims on my 2012 specialized S works epic with longer travel after market fork, that is used for trail riding/AM rather then cross country. Have to deal with very slippery wet roots/rocks commonly where I ride, which require running lower pressures for traction. Would like to get rid of the tire squirm and gain better traction in corners in the wet with fatter rims. 
Presently running stock roval control sl wheelset w/ 21mm ID W/ Nobby Nic 2.35's fr & back, 17 & 19 psi, and no, for all the flamers in this forum (more than the usual bunch of immature people in here), I have never broken a rim, in spite of riding faster than most of the other people in our area. 
Thanks for your help.


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## ThomasF (Oct 4, 2013)

i rode the Roval traverse fatties with a butcher control up front and slaughter in back. it didn't feel too blocked off, could still turn just fine with 650b


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## Ridnparadise (Dec 14, 2007)

meltingfeather said:


> I agree, though I also don't find it surprising. The bigger the mfr, the more the beureaucratic/administrative momentum is built into each move.
> Now throwing money to an "edgy" sub-brand or "development" entity could be interesting, but most shareholders are looking for quarterly dividends and couldn't care less about anything other than performance.


So what you are saying is that the people with the capacity and financial security to R&D stuff prefer to exploit those who don't to test the market and for increased corporate gain?


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## oldranger (Apr 14, 2011)

jmcdev1 said:


> Not to hijack the OP's thread, but...


http://forums.mtbr.com/29er-components/roval-traverse-sl-fatties-922275.html


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## Junersun (Jun 10, 2014)

jmcdev1 said:


> Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
> Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?
> Planning to put a wheelset with some wider rims on my 2012 specialized S works epic with longer travel after market fork, that is used for trail riding/AM rather then cross country. Have to deal with very slippery wet roots/rocks commonly where I ride, which require running lower pressures for traction. Would like to get rid of the tire squirm and gain better traction in corners in the wet with fatter rims.
> Presently running stock roval control sl wheelset w/ 21mm ID W/ Nobby Nic 2.35's fr & back, 17 & 19 psi, and no, for all the flamers in this forum (more than the usual bunch of immature people in here), I have never broken a rim, in spite of riding faster than most of the other people in our area.
> Thanks for your help.


I just got some Derby DH rims on my Ibis. I'm using butcher and slaughter for my tires and they are incredible in regards to traction. I can feel when the breaking point is though a lot sooner but it doesn't bother me. I live in Washington so I deal with a lot of slippery wet terrain. I have heard that slaughter is not very good for wet... I don't have enough experience using different tires. It's been working great for me!


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## jmcdev1 (Jan 1, 2011)

Thanks for the link to that thread, old ranger. Wasn't aware of it. 
I will also get a chance to try the butcher and slaughter on this wheel set when I borrowed my friends wheels soon. Thanks for the feedback guys.


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## LyNx (Oct 26, 2004)

I built a front Dually 45mm rimmed wheel to try 29+ for my rigid, was trying to figure what I'd run on the rear since it won't take a 29+, so widest would be a 29er 2.4" and wasn't sure if a Dually45 for that size tyre would be overkill or a 35mm rim would be enough. Decided to do some experimenting and threw a 2.25" Smorgasbord on the wheel, it's casing grew by 4mm _(as wide as the 2.4" Chunky Monkey on an i25 rim)_. Rode it and couldn't believe the change in the tyre, no rolling or squirming, just turn or lean the bike into the corner and you had solid traction _(I tried this tyre on the front once, did not like it)_.

Decided to pull that tyre off and mount a 2.4" Chunky Monkey, it's casing grew about 3.5mm and profile flattened out a bit, will be riding it tomorrow, but I think it'll grip insane. These two tyres IMHO are a good choice as on "normal <25mm internal rims, the tread is quite round and it squares off just a bit on the 45mm rims making the edge knobs just that bit easier to get too without extreme lean angles.

Pics attached of the Chunky Monkey on Dually45 and WTB i25, so that's an internal width difference of 14mm. Needless to say, I'm no pro anything, I absolutely love what the wider rim has done to how the tyre works and how solid it now is at low pressures without squirm, just like when I put my first set of decent "Fig" rims on my car coming from the standard factory rims, night and day difference.



jmcdev1 said:


> Not to hijack the OP's thread, but the majority of this thread has not dealt with downhill riding anyway. Just read all 20 pages of this thread trying to get some insight.
> Question for the one or two folks who posted that they ride the roval traverse fattie wheels in this thread: what tires have you tried with his wheel set and which ones worked the best in your opinion?...... Thanks for your help.


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## manitou2200 (Apr 28, 2006)

Just for some reference here; Mitch Ropelato is running the Roval Traverse SL Fatties on his Specialized Enduro 29r pro enduro bike as was stated earlier in this thread. I saw a video of his enduro bike on Vital MTB and he runs the Butcher and Slaughter tires on the SL Fatties. He also used the same Enduro 29 bike to race the Taxco Urban DH race with the SL Fatties and same tires above. There are at least 4 riders that I know of on the pro enduro circuit racing on these wide carbon wheels so it looks to be more than just hype. Here's a link to Kelly McGarry's Taxco DH run to give you and idea of what Ropelato ran these wheels and tires down.


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## zephxiii (Aug 12, 2011)

LyNx said:


> I built a front Dually 45mm rimmed wheel to try 29+ for my rigid, was trying to figure what I'd run on the rear since it won't take a 29+, so widest would be a 29er 2.4" and wasn't sure if a Dually45 for that size tyre would be overkill or a 35mm rim would be enough. Decided to do some experimenting and threw a 2.25" Smorgasbord on the wheel, it's casing grew by 4mm _(as wide as the 2.4" Chunky Monkey on an i25 rim)_. Rode it and couldn't believe the change in the tyre, no rolling or squirming, just turn or lean the bike into the corner and you had solid traction _(I tried this tyre on the front once, did not like it)_.
> 
> Decided to pull that tyre off and mount a 2.4" Chunky Monkey, it's casing grew about 3.5mm and profile flattened out a bit, will be riding it tomorrow, but I think it'll grip insane. These two tyres IMHO are a good choice as on "normal <25mm internal rims, the tread is quite round and it squares off just a bit on the 45mm rims making the edge knobs just that bit easier to get too without extreme lean angles.
> 
> Pics attached of the Chunky Monkey on Dually45 and WTB i25, so that's an internal width difference of 14mm. Needless to say, I'm no pro anything, I absolutely love what the wider rim has done to how the tyre works and how solid it now is at low pressures without squirm, just like when I put my first set of decent "Fig" rims on my car coming from the standard factory rims, night and day difference.


Hmm i'd like to see that same tire mounted on an Arch EX for comparison.


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## Preston67 (Mar 20, 2008)

I won't bring anything scientific to the discussion just my own experience.

I put on some Roval Fattie Carbons on my E29. Previously I had been running 23mm iWidth light-bicycle rims. These wheels arrived in January after ordering them in August. I put them on and actually "forgot" about them until I cranked up the season a few weeks ago. So I had no expectations when I headed out as opposed to the normal "Hey I bought this expensive thing let's see if I can tell the difference". 
I used the same tires, Butcher 2.3 front and Purgatory 2.3 back, normal pressure (26psi). 

I remember thinking "wow, really hero dirt today", and "man I'm getting nice grip in the corners" several times. It was only when I got home that I remembered I had a brand new "wide" wheelset on the bike. 

So for kind of a blind test, I felt the wheels made a noticeable improvement in cornering grip or at least cornering confidence. I had been running my previous setup all summer/fall going riding every weekend and more so I was very familiar with how the last setup felt.

Plus, they make the tires look really burly so that's cool.


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## PhxChem (Aug 4, 2010)

Is anyone REALLY hyping wider rims??









Nevermind.....carry on......


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## Guest (Feb 22, 2015)

PhxChem said:


> Is anyone REALLY hyping wider rims??
> 
> View attachment 966505
> 
> ...


If you think that's hype you should look up the definition of the word.

Here are a few from this site:
_2. Exaggerated or extravagant claims made especially in advertising or promotional material...
3. An advertising or promotional ploy...
4. Something deliberately misleading; a deception: ... To publicize or promote, especially by extravagant, inflated, or misleading claims...​_The example you provide meets none of these definitions. Not all ads are hype, this one is remarkably understated.


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> If you think that's hype you should look up the definition of the word.
> 
> Here are a few from this site:
> _2. Exaggerated or extravagant claims made especially in advertising or promotional material...
> ...


Except for the picture. Most people can't do that on a mountain bike. And the ad might suggest that you can in an indirect or subliminal way, if you buy their wide rims.


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## tigris99 (Aug 26, 2012)

Mountain Cycle Shawn said:


> Except for the picture. Most people can't do that on a mountain bike. And the ad might suggest that you can in an indirect or subliminal way, if you buy their wide rims.


Lmao, and kids belief they can be superman. Wth is the difference? Oh wait there isn't one. Pretty much no one except little kids and those with no education beyond elementary school would "think the rims makes them able to do that"


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## Mountain Cycle Shawn (Jan 19, 2004)

tigris99 said:


> Lmao, and kids belief they can be superman. Wth is the difference? Oh wait there isn't one. Pretty much no one except little kids and those with no education beyond elementary school would "think the rims makes them able to do that"


You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.


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## dirtrider76 (Sep 19, 2012)

Mountain Cycle Shawn said:


> You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.


Agreed


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## Guest (Feb 22, 2015)

Mountain Cycle Shawn said:


> You can laugh all you want, but subliminal advertising works on the subconscious mind and is an effective marketing tool.


But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.


It can be hype, please see post number 490.


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## pharmaboy (Nov 11, 2005)

craigsj said:


> But subliminal advertising is not hype. The suggestion was that this ad was an example of hype. It's just an example of plain old advertising.


Most advertising is hype. They make claims they can't back up. "Wider profile" is probably the only statement there that is unambiguous and can be backed up, the rest is puffery


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## Mountain Cycle Shawn (Jan 19, 2004)

It's a pretty good ad. And, it's not an all out lie like some ads you see.


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## JLF1200 (Sep 16, 2009)

"No actually if you look at it from a certain angle it's TOTALLY UNHYPED." 

Why the f*ck is this argument even happening?


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## Guest (Feb 23, 2015)

Mountain Cycle Shawn said:


> It can be hype, please see post number 490.


I saw post 490. Nowhere in the picture do they suggest you can ride like that if you had wider rims. If they did then that would be hype, instead it's merely advertising. There's a difference.



pharmaboy said:


> Most advertising is hype. They make claims they can't back up. "Wider profile" is probably the only statement there that is unambiguous and can be backed up, the rest is puffery


No, most advertising is not hype. Hype means something specific.

Now, if you think "more support, more traction, more control" are exaggerated or extravagant claims then you may claim hype...but you will lose that argument. Wider rims are used across many industries for just these reasons. It's a circular argument and those who reject these basic claims are deniers, nothing more.


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## Mountain Cycle Shawn (Jan 19, 2004)

craigsj said:


> I saw post 490. Nowhere in the picture do they suggest you can ride like that if you had wider rims. If they did then that would be hype, instead it's merely advertising. There's a difference.
> 
> No, most advertising is not hype. Hype means something specific.
> 
> Now, if you think "more support, more traction, more control" are exaggerated or extravagant claims then you may claim hype...but you will lose that argument. Wider rims are used across many industries for just these reasons. It's a circular argument and those who reject these basic claims are deniers, nothing more.


Haha, I guess you didn't understand what we were talking about when we were talking about subliminal advertising. That's a type of subliminal advertising.


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## Guest (Feb 23, 2015)

Mountain Cycle Shawn said:


> Haha, I guess you didn't understand what we were talking about when we were talking about subliminal advertising. That's a type of subliminal advertising.


Haha, and I guess you need it explained to you what the difference between hype and effective advertising is.

Do you believe that drinking Budweiser gets you the girls? Do you believe that are literally claiming that in their commercials? After getting turned down at the bar with Bud in hand, would you run home and start a forum thread entitled "Budweiser? Don't believe the hype..."?


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## eb1888 (Jan 27, 2012)

Preston67 said:


> I won't bring anything scientific to the discussion just my own experience.
> 
> I put on some Roval Fattie Carbons on my E29. Previously I had been running 23mm iWidth light-bicycle rims. These wheels arrived in January after ordering them in August. I put them on and actually "forgot" about them until I cranked up the season a few weeks ago. So I had no expectations when I headed out as opposed to the normal "Hey I bought this expensive thing let's see if I can tell the difference".
> I used the same tires, Butcher 2.3 front and Purgatory 2.3 back, normal pressure (26psi).
> ...





scottie mac said:


> My camber evo came equiped with Fattie ALs and I rode it one time that way before switching to my normal wheels - roval control carbons. I do feel the wider profile rim with Purgatorys front and rear did have a slight handling advantage over the narrow carbon controls. A buddy of mine who comes from the MX world, who is extremely in tune with his set ups, just purchased a pair of roval fattie carbon traverse wheels. He loves them. He also uses Purgatory tires on the front and we measured his tire profile and mine back to back. His tires were around 2.3mms wider than mine, matted, tubeless running his desired preasure (23psi). I typically run 24-25psi on mine.
> 
> I think there is an ever so slight advantage to the fatties, but it isn't anything like going from a 2.0 tire to a 2.3. Having said that, as mentioned above, with advances in tire designs, I can only see the advantages in the handling department only getting better. I don't think they are going to be a manadatory upgrade for everyone, but for those who like to push the edge, espescially pointed down, I could see it.
> 
> ...


You'll get even more out of the wide rims when you drop your pressure by 4-5psi. Think fat bikes. Wider wheels/tires=lower pressure=more traction.
I'm at 15-16 front and 20 rear with 2.2 XR1s.


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## oldranger (Apr 14, 2011)

For those of you reviewing this thread, in the hopes there might be a relevant comment. Don't try 15psi front and 20psi rear on a downhill (DH) bike with the rims and tires available in 2015. The only conditions I can think of that would warrant those low pressures are a VERY muddy race course where traction is severely limited, and you don't have mud spikes to use. 

On average conditions - those pressures wouldn't even support my 95lbs. 11 year old in the turns or rocks.

Edit: again, I'm providing these recommendations for a downhill bike. To clarify, that means you do not have to pedal it uphill, and for the majority of the time, you are pointed downhill at speeds between 15 mph and 35mph encounter rocks, turns and berms at those speeds. Maybe faster.


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## meltingfeather (May 3, 2007)

Ridnparadise said:


> So what you are saying is that the people with the capacity and financial security to R&D stuff prefer to exploit those who don't to test the market and for increased corporate gain?


not at all... wtf?


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## ColinL (Feb 9, 2012)

oldranger said:


> For those of you reviewing this thread, in the hopes there might be a relevant comment. Don't try 15psi front and 20psi rear on a downhill (DH) bike with the rims and tires available in 2015. The only conditions I can think of that would warrant those low pressures are a VERY muddy race course where traction is severely limited, and you don't have mud spikes to use.
> 
> On average conditions - those pressures wouldn't even support my 95lbs. 11 year old in the turns or rocks.
> 
> Edit: again, I'm providing these recommendations for a downhill bike. To clarify, that means you do not have to pedal it uphill, and for the majority of the time, you are pointed downhill at speeds between 15 mph and 35mph encounter rocks, turns and berms at those speeds. Maybe faster.


The forum won't let me give you any more rep right now, sorry. But a normal 26, 27 or 29" MTB tire does not have enough air volume to run 15psi without riding the rim. It's very basic physics. The notion of wider rims allowing lower tire pressures was thoroughly debunked several times in this thread, but people still believe it. LOTS of people who are probably itching to give you and me negative rep right now! 

Fatbikes can run 15 psi - they have a tad more air volume. 29+ (29x3) can probably do it as well.

Explanations for extremely low pressures on normal MTB tires:
1) defective air pressure gauge
2) rolling around on their rims without knowing it
3) never takes a fast corner
4) doesn't drop or jump
5) doesn't hit rocks or roots at high speed


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## OriginalDonk (Jul 8, 2009)

Thoroughly debunked? 

What I see here is a mix of anecdotal musings and a bit of marketing material. No doubt people have very disparate opinions about what, if any, performance changes you can expect from going to a wider rim. Some "feel" no change and some "feel" a huge difference. There are so many variables involved (terrain, tire design, riding style, etc.) and we are nowhere close to thoroughly debunking anything. Your perspective on things should dictate whether you spend your coin on a wider wheel or not. 

I've started a list of professions you probably aren't involved in:

1) Statistician
2) Physicist
3) Mechanical engineer
4) Judge
5) Economist
6) Political scientist
7) Theoretical mathematician


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## aerius (Nov 20, 2010)

ColinL said:


> Fatbikes can run 15 psi - they have a tad more air volume. 29+ (29x3) can probably do it as well.


In the old days of Nokian Gazzaloddis, we did run under 20 psi. But that's a 26x3" tire with a stupidly stiff casing that required motorcycle tire levers to install onto a rim. Darn thing would practically hold up the weight of the bike with no air in it.


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## tigris99 (Aug 26, 2012)

Simple issue is this, wider means lower pressure allowed, simply based on increase in contact patch (which is where weight is supported). Same weight over increased area allows lower pressure to support the load.

Increased contact patch also mean more rubber in contact with the ground. Equals more traction.

In comes the hype: The changes aren't that big, in a scientific type sense. Lower pressures, from a 17mm inner to a 30mm inner width, ya that's something you'd notice with a few psi. 23/25 up to 30mm inner, its nothing more than pressure variance you get with weather changes. Really low pressures people think is the greatest thing, ya if your a low speed rock crawler. Beyond that there is a reason why burping is a problem, same reason any tubeless tire on car, motorcycle, etc, can and does loose tire off bead on a hard turn. Low pressures at speed is just asking for problems. wonder why I never dinged a rim....oh wait cause I run enough pressure to support the weight so I don't tag my rims when it gets rough. 

Fat bikes low pressures, its for float and allowed pressures are directly an effect of volume. You increase contact patch by 2-3x, you can run less pressure, increase contact further for more float and traction.

Traction, that's been proven for decades, wider is better. No hype or anything there. Just like going from a 1.9 tire to a 2.4, traction just BETTER. Equal tire, bike, etc, wider is going to be better for traction in all aspects.


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## ColinL (Feb 9, 2012)

tigris99 said:


> Simple issue is this, wider means lower pressure allowed, simply based on increase in contact patch (which is where weight is supported). Same weight over increased area allows lower pressure to support the load.
> 
> Increased contact patch also mean more rubber in contact with the ground. Equals more traction.


I think we can all agree that bicycle tires are supported by air pressure, and that the tire carcass itself does not offer any meaningful support. Isn't that evident by handling any unmounted tire, or by observing a bicycle at rest on a flat tire? The specific pressure required is determined by the tire, certainly - but the manufacturer has thoughtfully printed this on the side of the tire.

Consider this in contrast to run-flat car tires, which are specifically built to have a really tough sidewall and tire carcass that can support the weight of the car temporarily with low / no air pressure. You can't do that with a mountain bike tire.

So, regardless of the shape of the contact patch, with the same tires on different wheels you have the same air volume --excluding any differences to the rim bead depth & shape-- and same air pressure required to support a given usage.

Also, let's not overlook that the side knobs on tires are angled and meant to be used when the bike is leaned into a corner. If they're fully engaged when the bike is upright, yes, I would agree you've got more traction. You've also got a lot more rolling resistance, and square tires are kind of hard to lean compared to rounded.


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## JLF1200 (Sep 16, 2009)

MTBR is hilarious. It's really the only bike forum where you can find this kind of stuff. "You are CLEARLY not a statistician or a physicist!"

ZING. Got him!

But anyway...



> Explanations for extremely low pressures on normal MTB tires:
> 1) defective air pressure gauge
> 2) rolling around on their rims without knowing it
> 3) never takes a fast corner
> ...


This is pretty accurate.


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## Mountain Cycle Shawn (Jan 19, 2004)

ColinL said:


> I think we can all agree that bicycle tires are supported by air pressure, and that the tire carcass itself does not offer any meaningful support.


This is so untrue, I don't even know where to start.


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## turbodog (Feb 28, 2004)

Some of the lack of experience in this thread is breathtaking.


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## Mountain Cycle Shawn (Jan 19, 2004)

turbodog said:


> Some of the lack of experience in this thread is breathtaking.


To say the very least! I'd probably get in trouble If I said what I really wanted to say.


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## manitou2200 (Apr 28, 2006)

turbodog said:


> Some of the lack of experience in this thread is breathtaking.





Mountain Cycle Shawn said:


> To say the very least! I'd probably get in trouble If I said what I really wanted to say.


So very true and I'm also trying to behave myself here.

To all here: It would be great to keep this discussion to constructive input! If you haven't ridden any of the wider rims then I suggest you take a test ride on any of them then bring your feedback from that experience here. Otherwise it's all theories and suppositions!


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## Mountain Cycle Shawn (Jan 19, 2004)

It's all opinion with nothing to back it up. And you know what they say about that!


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## Junersun (Jun 10, 2014)

I came from Stan Flow Ex and now I have a pair of Derby's. Stuck with the same specialized butcher up front and now run slaughter in the back. Granted a lot of things changed; Alu to Carbon, wide to WIDE, tire pressure difference, etc etc. but I am thoroughly enjoying my wide rims. traction is incredible but I do feel it breaking loose on flat turns sooner. I'm looking forward to tire companies accompanying these wide tires someday.

Maybe a 2.2 inch tire with some crazy side knobs?


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> It's all opinion with nothing to back it up. And you know what they say about that!


OK, you obviously have opinions but I haven't found much substance to them here in this thread. So why don't you pick a DH trail, same day, bike, same tires with your normal AM/ DH rim and a set of wide rims. Run them back to back multiple times, average your times in each then let us know what your findings are.


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## MontrealMarc (Dec 17, 2014)

ColinL said:


> ...So, regardless of the shape of the contact patch, with the same tires on different wheels you have the same air volume --excluding any differences to the rim bead depth & shape-- and same air pressure required to support a given usage....


No true.
A quick schematic:







Same tire on both, the wider the rim get, the more volume you have.


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## oldranger (Apr 14, 2011)

Can you redo that diagram with a realistic difference between the internal rim widths?

In that image you are comparing a 19mm wide rim to a 35mm wide rim. Try 25mm to 29mm. That's more appropriate.


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## MontrealMarc (Dec 17, 2014)

The exact numbers are irrelevant. If it's a wider rim you'll have a bigger volume, that's all.
You may think that a small increase in rim width won't add enough volume to make a difference and I won't argue with you.
The point is ColinL was just way too far in his arguments.


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## ColinL (Feb 9, 2012)

You might also re-draw it with a tire that doesn't inflate like a balloon.

Assuming the tire doesn't change, it would not be possible for it to fit on a wider rim and yet not lose any height / rolling diameter.

That extra contact patch has to come from somewhere, right? And it comes from a change in tire profile. It is more square and less round, in real life, unlike your drawing.


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> OK, you obviously have opinions but I haven't found much substance to them here in this thread. So why don't you pick a DH trail, same day, bike, same tires with your normal AM/ DH rim and a set of wide rims. Run them back to back multiple times, average your times in each then let us know what your findings are.


I'm not you. You need to go do those things for yourself to decide if they are right for you. We could tell you how much better wide rims are, till we're blue in the face. You won't get it, till you try it. Go try it. This is the whole problem here. At least half of you want to spout off at the mouth and have never tried wide rims.


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## MontrealMarc (Dec 17, 2014)

It doesn't matter, any profile you fancy, it will still have a bigger volume if the rim is wider.
In the drawing above, the curve representing the tire section is the exact same lenght in both views.


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> I'm not you. You need to go do those things for yourself to decide if they are right for you. We could tell you how much better wide rims are, till we're blue in the face. You won't get it, till you try it. Go try it. This is the whole problem here. At least half of you want to spout off at the mouth and have never tried wide rims.


Dude, I already know the difference and benefits of the wider rims. I own rims with ID's from 22-40mm. I have a set of flow rims and the Roval SL Fatties mounted with the same tires. I'm just tired of all the ******** comments from so called riders here who've never ridden wider rims yet seem to know or are trying to hypothesize that they do not work.

The other dumb ass argument going on here is the volume change debate. Think about this, if the bed width of the rim widens, then there is more area between the beads of the tire when they are seated. The internal circumferential cross section of the tire itself will not change so that's a given area. Wider rims give tires more volume period!

Edit: My mistake I confused you for one of the naysayers of wide rims.


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## oldranger (Apr 14, 2011)

Another fact that still holds true a year after I started this thread is that in 2015 the bike manufacturers and race teams are still NOT spec'ing their downhill (DH) bikes with rims any wider than 23mm - 27.5mm inner width.

And NO tire manufacturers are making DH casing tires specifically designed for these wider rims that are on the market from Niche players like Derby.

In over a year, no one has proven this false. So I'm done contributing to this thread until that changes. I'll see you guys at the races on my old 26" DT Swiss FR600s. My name is Andy Richter. I'm an old guy, so if you pass me...try not to throw too much roost on me from your awesome wide rims. I'll keep my money for new tires, bearings, brake pads, and lessons for my son.

P.S. Thanks for the vigorous debate.
P.S. Traction is only one of many functional requirements of a tire.


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## eb1888 (Jan 27, 2012)

So, moving on with the riders who have wide rim experience, we see added volume and a larger contact area. The area increase gives some more traction. 
The added volume allows lower air pressure before you get rim hits. From this we get an even larger contact patch with more deformation when going over bumps for even better contact and more traction. 
What else. 
The larger volume and lower pressure adds tire compliance from the standpoint of ride comfort. Small bump compliance that helps some forks which lack enough of that. This can be really good for hardtails. Maybe give added life to aluminum frame bikes.
And more.
The spreading apart of the tire beads gives better sidewall support. This is pretty significant for my riding. That support stops the tire tread from abruptly losing grip like when the less supported sidewall rolls over under quick cornering moves. I don't washout from a tracking mistake...basically anymore. I have time to recover instead of hitting the dirt. That's a big plus. 
It could be especially valuable for slow healers.


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## bholwell (Oct 17, 2007)

eb1888 said:


> So, moving on with the riders who have wide rim experience, we see added volume and a larger contact area. The area increase gives some more traction.
> The added volume allows lower air pressure before you get rim hits.


I can't say that I completely agree with you here. The area of the contact patch is solely dependent upon the load carried by the tire and the inflation pressure within it. A wider rim will change profile of the tire, which in turn will have an effect on the shape of the contact patch, and the pressure distribution within it.

And added tire volume should actually make for a more linear spring rate while deforming over an obstacle, which would make rim hits more likely. Larger tires are less prone to pinch flats simply because there is a greater distance the tire must deform before the tire is totally compressed against the rim. But moving to a wider rim while using the same tire doesn't have much of an effect on the tire's section height.


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## Mountain Cycle Shawn (Jan 19, 2004)

bholwell said:


> I can't say that I completely agree with you here. The area of the contact patch is solely dependent upon the load carried by the tire and the inflation pressure within it. A wider rim will change profile of the tire, which in turn will have an effect on the shape of the contact patch, and the pressure distribution within it.
> 
> And added tire volume should actually make for a more linear spring rate while deforming over an obstacle, which would make rim hits more likely. Larger tires are less prone to pinch flats simply because there is a greater distance the tire must deform before the tire is totally compressed against the rim. But moving to a wider rim while using the same tire doesn't have much of an effect on the tire's section height.


Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.


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## bholwell (Oct 17, 2007)

Mountain Cycle Shawn said:


> Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.


You seem to be making quite a few assumptions.

Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?


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## turbodog (Feb 28, 2004)

bholwell said:


> You seem to be making quite a few assumptions.
> 
> Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?


I know, right...?


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## Mountain Cycle Shawn (Jan 19, 2004)

bholwell said:


> You seem to be making quite a few assumptions.
> 
> Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?


It makes the sideway of the tire a lot stronger. The verticle force with a wide rim is able to be transferred up/down the whole length of the sidewall, instead of crossing the thin part of the sidwall because the sidewall is no longer shaped like a light bulb. It's the single biggest reason that makes wider rims better. In fact, it makes the sidewalls so much stronger that you are able to run much lower pressures. It's not the small increase of volumn that allows lower pressures, it's the better position of the sidewalls. And, roadies are also benefiting from wider rims, for the same reasons.


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## meltingfeather (May 3, 2007)

Mountain Cycle Shawn said:


> Except, you don't seem to realize, probably because you haven't read the whole thread or other threads on the same subject, that a wider rim puts the sidewalls of the tires in a position to make them much stronger.


Yeah... professional tire designer doesn't realize what rim width does to profile, which he could (should?) have learned from MTBR, according to you. 
C'mon, dood.


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## pharmaboy (Nov 11, 2005)

bholwell said:


> You seem to be making quite a few assumptions.
> 
> Do you claim that because the sidewalls of the tire are slightly more vertical, they are able to take a compressive load, and that "makes them stronger"?


While you are here, can you please give your take on pressure. My understanding of the physics is that wider allows lower pressure before burping becomes an issue, but that rim strikes will occur more often because of the lower pressure - ie there is no real difference between normal and wide for rim strike occurrence.


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## Mountain Cycle Shawn (Jan 19, 2004)

meltingfeather said:


> Yeah... professional tire designer doesn't realize what rim width does to profile, which he could (should?) have learned from MTBR, according to you.
> C'mon, dood.


Tire designers have done the best they can with what they have been given. People want big tires, regardless of the skinny rims and that's what the tire companies have given us. Wait till tire companies start making tires for these wide rims. Then you'll really see some performance gains. The stronger sidewall is one reason why the narrower tires seen to work better with wide rims. Again, it's all about sidewall strength at supper low pressures that allows more tread to be in contact with the ground, without rim strikes.


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## aerius (Nov 20, 2010)

Mountain Cycle Shawn said:


> It makes the sideway of the tire a lot stronger. The verticle force with a wide rim is able to be transferred up/down the whole length of the sidewall, instead of crossing the thin part of the sidwall because the sidewall is no longer shaped like a light bulb. It's the single biggest reason that makes wider rims better. In fact, it makes the sidewalls so much stronger that you are able to run much lower pressures.


If this were true I could let all the air out of a tire mounted on wide rims and it'll hold the weight of the bike off the ground, whereas the same tire on a normal rim will bottom out under the weight of the bike. Too bad it doesn't work that way. You're telling me that a flimsy tire sidewall can support heavy compressive loads if you could just make it vertical, yeah, and you can push on a string if it's in a straight line. Pull the other one.


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## bholwell (Oct 17, 2007)

pharmaboy said:


> While you are here, can you please give your take on pressure. My understanding of the physics is that wider allows lower pressure before burping becomes an issue, but that rim strikes will occur more often because of the lower pressure - ie there is no real difference between normal and wide for rim strike occurrence.


Your understanding of the physics behind it jive with my own. Spacing the beads further apart gives the tire a more stable "base"; less of a pivot point. Imagine a rim so narrow that the beads are touching. I'd wager you'd be able to roll the inflated tire laterally with your hands fairly easily. Rider rim = more stable base = less lateral roll = less burping while cornering or landing a jump sideways. I think this is mostly why people claim they can ride a wider rim at lower pressures.

Regarding rim strikes, since the volume of the tire is greater, the spring rate will be more linear, so based on that alone the likelihood of rim strikes should increase. There may be other factors at play, however. Imagine running over a tall skinny root at high speed. The height of the root is such that when the root is directly over the wheel's axle and the tire is compressed all the way to the rim, the tire does not come into contact with the ground at all. In this scenario, the contact patch of the tire is only contacting the root. A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.


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## Mountain Cycle Shawn (Jan 19, 2004)

aerius said:


> If this were true I could let all the air out of a tire mounted on wide rims and it'll hold the weight of the bike off the ground, whereas the same tire on a normal rim will bottom out under the weight of the bike. Too bad it doesn't work that way. You're telling me that a flimsy tire sidewall can support heavy compressive loads if you could just make it vertical, yeah, and you can push on a string if it's in a straight line. Pull the other one.


Now you're just getting stupid. Of course the tire has to have air in it to do its job. That's the way it was all engineered. Mountain bike tires aren't Runflats. You wouldn't let all the air out of your air shock and expect it to work properly. Well, maybe you would but the rest of us wouldn't do that.


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## Mountain Cycle Shawn (Jan 19, 2004)

bholwell said:


> Your understanding of the physics behind it jive with my own. Spacing the beads further apart gives the tire a more stable "base"; less of a pivot point. Imagine a rim so narrow that the beads are touching. I'd wager you'd be able to roll the inflated tire laterally with your hands fairly easily. Rider rim = more stable base = less lateral roll = less burping while cornering or landing a jump sideways. I think this is mostly why people claim they can ride a wider rim at lower pressures.
> 
> Regarding rim strikes, since the volume of the tire is greater, the spring rate will be more linear, so based on that alone the likelihood of rim strikes should increase. There may be other factors at play, however. Imagine running over a tall skinny root at high speed. The height of the root is such that when the root is directly over the wheel's axle and the tire is compressed all the way to the rim, the tire does not come into contact with the ground at all. In this scenario, the contact patch of the tire is only contacting the root. A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.


This is also true. Less of a light bulb effect going on.


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## rfxc (Oct 18, 2004)

As a guy who's done everything in the last 14 years from cat 1 XC in Wisconsin, Iowa, and the midwest, to DH runs in CO and CA and UT, let me just share this perception/observation: people ride mountain bikes VERY differently. even one person's "aggressive rocky DH run" is different than another's. 
So, for one person: "works great, no rim strikes at less psi, etc" good for you.
For another person: "too many rim strikes, destroying rims, x tires work fine, y tires don't." Also good for you.

Some people push bikes HARD on tame terrain, other people are easy on harsh terrain, and vice versa. 

Apples and oranges. 

Given that, thanks everyone for sharing your personal experiences with as much context as possible, and I appreciate the conversation, both the storytelling and the hypothesizing.


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## giangnguy3n (Nov 14, 2012)

May be friday u work?


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## meltingfeather (May 3, 2007)

rfxc said:


> As a guy who's done everything[...] hypothesizing.


So what you're saying is one rider's subjective trail impressions don't mean anything necessarily to the next rider... which is my motto. On MTBR though, each person's opinion is gospel (to them) and a universal law that applies to everyone.


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## ca_rider (Feb 3, 2008)

Mountain Cycle Shawn said:


> Now you're just getting stupid. Of course the tire has to have air in it to do its job. That's the way it was all engineered. Mountain bike tires aren't Runflats. You wouldn't let all the air out of your air shock and expect it to work properly. Well, maybe you would but the rest of us wouldn't do that.


You contradict your previous argument with this one. The point you make here is that the load is supported by the internal pressure, not the sidewalls. Yet previously you claim the opposite.

It may be useful for you to clarify your use of 'work properly'. Are you saying that when inflated, the sidewalls support compressive loads? If so, it is useful to note that while riding the resulting deflection of the sidewall is supported by the internal pressure, not the sidewall itself. This mechanism of support, namely by pressure, is not controlled by the direction of the sidewall orientation. Instead, the sidewall is supported by the transfer of force via internal pressure which seeks to balance the tensile stresses and compressive forces on the tire. However, pressure is a scalar and not a vector quantity so there is no fundamental mechanism to support your argument.

Said another way, pressure has no directionality so it cannot operate differently based on the angle of the sidewall.

Please let me know if I missed an alternate mechanism you may be considering.


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## meltingfeather (May 3, 2007)

ca_rider said:


> Said another way, pressure has no directionality so it cannot operate differently based on the angle of the sidewall.


uh... yes it does. Pressure always acts normal to the surface it is acting on. Change the angle of the surface (sidewall) and you change the resultant force (vector). Changing the action-reaction at the rim bead, which this translates to, as well as the sidewalk buckling, changes the behavior of the interface on both ends: tire-rim and tire-ground.
Ever heard of a Hemi?


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## ca_rider (Feb 3, 2008)

I know you are a CE - I suggest you reconsider wrt projected area.

Cheers.


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## Yody (Jan 21, 2008)

Funny watching people argue engineering points. everyone doesn't want huge tires that create steering lag and become very heavy. just skip the whole wide rim thing and just go full fat bike if that's what you want. wide rims are not new, neither are big tires. I've found people who like this setup spend most of their time straight up n down and not leaned. traction is cool and all but is not the end all of riding. you want traction but you also need some loss of traction in a predictable fashion. normal tires on ultra wide rims do not do that.


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## meltingfeather (May 3, 2007)

ca_rider said:


> I know you are a CE - I suggest you reconsider wrt projected area.
> 
> Cheers.


If this was directed at me (being a CE):
F (vector) = PA is not independent of the orientation of the A. The orientation of the surface that the pressure is acting on defines the directional (vector) component of the force. This is not engineering but high school physics. Even a 5 minute lesson on wikipedia's pressure page will tell you that.


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## pharmaboy (Nov 11, 2005)

meltingfeather said:


> So what you're saying is one rider's subjective trail impressions don't mean anything necessarily to the next rider... which is my motto. On MTBR though, each person's opinion is gospel (to them) and a universal law that applies to everyone.


That's the situation across the Internet, personal experience trumps science. That's how we have an anti GMO movement, anti vaxers etc. The world is full of people who think anecdote trumps understanding.

That anecdotal stuff is what originally drove the creation if this thread - people who have tried and loved the Kool Aide, convinced wide is better in every respect without a downside. Basic applied logic should tell anyone, that there has to be a downside and that there also has to be a point where wider is worse.

The only reason I joined this thread is because one aspect of the preaching is about lower pressures, and the advice on the Chinese rims thread, has been about 5psi less with wider rims, and people are amazingly surprised that they are striking the rims and breaking them.

The outcome of lower pressure is predictable by rudimentary physics, nay, even rudimentary logic, yet people continue to get advice to go far lower.


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## Mountain Cycle Shawn (Jan 19, 2004)

ca_rider said:


> You contradict your previous argument with this one. The point you make here is that the load is supported by the internal pressure, not the sidewalls. Yet previously you claim the opposite.
> 
> It may be useful for you to clarify your use of 'work properly'. Are you saying that when inflated, the sidewalls support compressive loads? If so, it is useful to note that while riding the resulting deflection of the sidewall is supported by the internal pressure, not the sidewall itself. This mechanism of support, namely by pressure, is not controlled by the direction of the sidewall orientation. Instead, the sidewall is supported by the transfer of force via internal pressure which seeks to balance the tensile stresses and compressive forces on the tire. However, pressure is a scalar and not a vector quantity so there is no fundamental mechanism to support your argument.
> 
> ...


Air pressure is a constant here. Tires depend on air in them to keep the tire in the correct position so the tire can do its job properly. I'll give you my example: Spinergy Enduro wheels with a 26mm rim setup tubeless, can be pinch fattened by me at 25psi. With X King 2.4" tires. This setup has a lightbulb look to it. Where the rim is the part that screws into the socket and the tire is the light bulb. At 25 psi you can grab the tire with your hand and flex it back and forth. The tire is so round at the sidewalls that its in a very bad position to resist the forces acting on it. The same exact setup with 40mm rims can't be pinch flattened by me even at 15psi. Grab this tire with your hand and you can't flex the tire as much as the other setup. This setup no longer has the lightbulb look to it. You can now see, just by looking at it that the tire can now better handle the verticle forces being applied to it, because the sidewall is more verticle. And side loads are handled better because of the wider rim. The difference is not caused by air volumn. Because there is almost no change in air volumn between the two setups. This is because with the 40mm rims the tires circumference doesn't change, the side knobs actually get a tiny bit more narrow, but they stand up higher, the top of the tread flattens out a bit. The very center wants to fold in towards the rim, but it can't because of the increased sidewall tension. So, there are three things here that make the tire stronger with a 40mm rim. The tire sidewall is in a better position to handle verticle loads, the sidewall now has more tension and the wide rims help the tire deal with the side loads better. Now picture two light bulbs the same size. One has a 26mm socket end and one has a 40mm socket end. It's going to take a lot more force for you to grab and break off the light bulb with the 40mm base. It would also be harder to break that same bulb by holding the socket end and slamming it straight down on a flat surface, compared to the bulb with the 26mm base. Just picture in your mind how a big volumn tire changes as it goes from having a narrow width at the bead to having a wide width at the bead. Play that over and over in your mind until you see it and you'll understand. It just takes a while to get it.


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## beanbag (Nov 20, 2005)

bholwell said:


> A tire on a wider rim might allow the tire to spread out (width-wise) across the root more, effectively yielding a larger contact patch, and thereby helping reduce the chance of pinch-flatting. I would like to test this theory, but I'd need to make a bicycle wheel adapter for my company's Ektron vertical load tester.


This makes sense to me too. I think it has very little to do with the vertical-ness of the sidewalls, but rather that the force that the tire pushes back with is related to the pressure x length (or area) of the "flat-spot" due to tire deformation. And a wider rim causes a tire to put down a bigger flat spot. However, tire deformation forces are rather complicated due to a non-stretchy casing, so probably a real test is best instead of hypothesizing.
Also, this benefit is totally cancelled out if you run a lower pressure.


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## Guest (Feb 26, 2015)

pharmaboy said:


> That anecdotal stuff is what originally drove the creation if this thread - people who have tried and loved the Kool Aide, convinced wide is better in every respect without a downside.


One read of the original post shows this not to be true. The "anecdotal stuff" came from the OP, not the other way around. You're showing your bias here.



pharmaboy said:


> The only reason I joined this thread is because one aspect of the preaching is about lower pressures, and the advice on the Chinese rims thread, has been about 5psi less with wider rims, and people are amazingly surprised that they are striking the rims and breaking them.


Yes, there is stupidity on both sides of the argument. That's what you get with tribalism and this has never been anything but a tribalist thread. When winning is all that matters, good information loses.


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## bholwell (Oct 17, 2007)

beanbag said:


> This makes sense to me too. I think it has very little to do with the vertical-ness of the sidewalls, but rather that the force that the tire pushes back with is related to the pressure x length (or area) of the "flat-spot" due to tire deformation. And a wider rim causes a tire to put down a bigger flat spot. However, tire deformation forces are rather complicated due to a non-stretchy casing, so probably a real test is best instead of hypothesizing.
> Also, this benefit is totally cancelled out if you run a lower pressure.


Absolutely. I'd wager I'm the only one in this thread who has actually performed vertical displacement testing on a tire in the lab. The sidewall of a bicycle tire does not handle vertical loads, as Mountain Cycle Shawn believes. The carcass of today's bicycle tires are so thin, it's simply not possible. Now if we're talking about 8 Ply Industrial tires at very low pressures on very narrow rims (compared to the design rim width), then yes, this theory has merit. But these tires are 8 ply in order to have a very high operating pressure to be able to carry a very high load, and they are always used on the specified design rim.


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## Mountain Cycle Shawn (Jan 19, 2004)

In a light bulb shape tire and rim the load crosses a thin section of tire as if going through the side of the tire because of the tires angle. With a wide rim the force is able to travel through a much longer section of the sidewalk because the sidewall is now more verticle. There's a reason why they don't use rims and tires that have a lightbulb shape on dirt bikes.


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## bholwell (Oct 17, 2007)

Mountain Cycle Shawn said:


> In a light bulb shape tire and rim the load crosses a thin section of tire as if going through the side of the tire because of the tires angle. With a wide rim the force is able to travel through a much longer section of the sidewalk because the sidewall is now more verticle.


No.



Mountain Cycle Shawn said:


> There's a reason why they don't use rims and tires that have a lightbulb shape on dirt bikes.


Yes, and it's because the tires are better supported laterally. The rim and tire widths of off-road motorcycles have nothing to do with supporting a vertical load. I honestly cannot believe you are attempting to educate me on tire dynamics.


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## ColinL (Feb 9, 2012)

bholwell said:


> I honestly cannot believe you are attempting to educate me on tire dynamics.


ROFLMAO.

I'm pleased to see that I was right about air pressure supporting the tire, and I humbly admit that I was wrong about the air volume changing on a wider rim. However, the actual change is considerably less than montreal marc's original diagram.

Still, I'm here to learn. I know the difference between opinion and fact. It's perfectly fine for people to have the opinion that they _like_ wide rims. It remains to be seen that they are _factually_ better in measurable ways.


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## eb1888 (Jan 27, 2012)

Anecdotal stuff has its value because it usually involves a direct comparison between two different things. Tire A on 21mm inside rim and tire A on 30mm inside rim over the same terrain. A person gets very familiar with terrain features and handling limits when he rides the same loop many multiple times.
No engineering degree is needed to register a ride and handling difference.
A degree may help if a finite quantification of any difference was necessary.
It's just not necessary for a large group of riders. They can get the experience without the numbers.
You engineering guys who haven't ridden wides in a direct comparison aren't going to add much for that large group.
Those who can make a direct comparison or do some other testing could be helpful for the non riding engineers.















Here's my example from actual riding.
Nobby Nic vs XR1, pretty similar handling and sized tires.
There is a major difference over the hardpack with rocky rooty segment and lots of different turn type terrain I have ridden thousands of times.
That sidewall support at 4 psi lower pressure will not abruptly washout and put me on the dirt. The added volume and lower psi without rim hits contributes a lot of comfort from tire compliance. I know the feel of each feature of my trail. No way would I ever go back to skinny rims.
The tire on the 30mm rim doesn't even look wide anyway, it looks normal. The ArchEx setup looks goofy.


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## IPunchCholla (Dec 8, 2013)

ColinL said:


> ROFLMAO.
> 
> I'm pleased to see that I was right about air pressure supporting the tire, and I humbly admit that I was wrong about the air volume changing on a wider rim. However, the actual change is considerably less than montreal marc's original diagram.
> 
> Still, I'm here to learn. I know the difference between opinion and fact. It's perfectly fine for people to have the opinion that they _like_ wide rims. It remains to be seen that they are _factually_ better in measurable ways.


I believe it has been shown , factually, that wider rims support higher lateral loads with less deflection (as per Specialized's testing). What this means is that, IF your riding style/terrain allows you to run lower pressures without rim strikes, then you can benefit from riding wider rims as they will allow those lower pressures (hence larger patch, hence more traction) without the tire rolling on the rim. Of course that is assuming traction is a goal and the change in tire profile isn't too much of a trade off.


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## HillDancer (Dec 10, 2012)

Some relevant statements made by Specialized engineer Jason Chamberlain: "...contact patch doesn't change size with different wheel sizes - it just changes shape. The only way to truly increase your contact patch is to lower your pressure. The only way to lower your pressure is with larger volume." "...wider rims gives you more volume without increasing tire size and adding casing. It also better supports the sidewalls..." Roval Traverse Fattie SL Wheels - NSMB.com

A review with images of the devices used by Specialized to measure deflection: First Ride: Roval Traverse Fattie Wheels - Super Wide and Super Fast - Pinkbike

Art's Cyclery Blog with more relevant input on this subject: Art's Cyclery Blog » Science Behind the Magic | Wide MTB Rims


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## Mountain Cycle Shawn (Jan 19, 2004)

HillDancer said:


> It also better supports the sidewalls...


Oh gosh, ****ing imagine that!!


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## JLF1200 (Sep 16, 2009)

Here's what I-9 had to say:

"Optimized inner rim width - With class leading Inner width to weight ratios already in place for our Torch series Aluminum rims, Industry Nine is no stranger to the recent push for wider inner width (IW) rims. So if wide is good, wider is better right? Based on our testing however, we found that there are optimal inner widths for each category of bike and tire:
- Current Mtb. tire technology is based on established rim profiles. Tire designers create tread profiles with a specific orientation on the tire casing to function optimally on a given rim inner width. If the IW of a given rim is too far outside of this range the tread pattern (particularly the shoulder blocks) can no longer function properly. 
Based on our testing and feedback from tire manufacturers, we came to a consensus on ideal rim widths for given tire categories. XC and intermediate Trail tires (usually 1.9-2.25" widths) are designed to function best on 18-25mm IW rims. Aggressive Trail and Enduro tires (usually 2.2-2.4mm widths) are optimized for 21-29mm IW rims, and DH/Park tires (usually 2.3-2.7" widths) are optimized for 25-31mm IW rims. "Plus" size and Fat Bike tires form their own categories and are designed specifically for much wider rims, with 40+mm inner widths on "plus" size rims, and 60-90+ mm inner widths for fatbike rims depending on tire widths. 
- As many riders have experienced, rims on the narrow end of the IW scale offer poor tire support and tires easily fold over and lose traction under hard cornering, so in comparison narrow "old school" rims, a wider inner width offers a lot of advantages vs. traditional narrow IW rims.
- Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so "square" that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail. 
- Rim and Tire Sidewall impact protection - with wider inner widths comes wider rim profiles overall. So for example a 35mm IW rim is generally going to have a 40+ mm outer width. On technical rocky trails a wider rim is much more susceptible to sidewall impact damage as the tire does not shield the rim from loose rocks, lateral impacts etc. Additionally the cornering tread blocks no longer shield the tire sidewalls from rocks leaving the tire much more susceptible abrasion and damage due to rock impacts. 
- Weight - all things being equal, a wider rim is going to be heavier. More surface area requires more carbon, which can completely offset the weight benefit of carbon rims. 
Taking this into account we designed the Pillar carbon series rims with inner widths which are in line or slightly wider than our current aluminum rim widths (depending on the model). The rims feature a hookless bead wall, which optimize the inner rim width of each model to be on the wide end of the spectrum for the intended tire and usage category. As tire design evolves there is no doubt that their will continue to be opportunities for wider rim technologies (after all no one wants to ride a 4.8" fatbike tire on a 19mm IW rim). However, we feel the PillarCarbon rims offer the prefect balance of IW, lateral stiffness, strength, and weight to accommodate today's XC, Trail, and Enduro Tires."

First comment below the article:
First Look: Industry Nine PillarCarbon Wheels - Mtbr.com


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## oldranger (Apr 14, 2011)

Here's what I-9 built for DH: 
First introduced in 2006, the I9 Enduro wheelset was built for those who wanted a bulletproof wheelset for aggressive riding. Tested extensively on the rigorous trails of Pisgah and Dupont State Forest, the new PillarCarbon Enduro 27.5-inch wheelset is ideally suited for long-travel full-suspension bikes. Featuring 32-spoke construction, 26.25mm inner rim width and 31mm outer rim width, the PillarCarbon Enduro 27.5-inch wheelset is still ultralight at just over 1400 grams while accommodating riders up to 220 pounds.


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## oldranger (Apr 14, 2011)

Sorry guys, I'm going back on my promise to leave the thread...I just couldn't pass up the latest comments with folks trying to 'school' bholwell on tire design.

Bholwell, I didn't come right out and ask you last year what rim width you would recommend for competitive DH racers using the Minion DHR2, Minion DHF, and High Roller tires...but I would love to know your opinion.


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## eb1888 (Jan 27, 2012)

Many riders have experienced a 30mm inside or larger rim working with a broad range of tires with a rounded tread profile. Relatively few tires are squaring off. 
It becomes possible to get more performance from the next lighter less aggressively profiled faster rolling tire offered in a manufacturer's line. So you don't always need as much knob for traction anymore. 

"- Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so “square” that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail." 

I don't think this statement by I-9 is specific enough to have value right now until a list is developed. Ibis says to pick tires with a rounded tread cap.

Riding XC to All Mountain terrain where lower pressure will work without rim hits. Could be the areas that see the most benefit. DH not so much.


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## ColinL (Feb 9, 2012)

JLF1200 said:


> Here's what I-9 had to say:
> (snipped)
> 
> First comment below the article:
> First Look: Industry Nine PillarCarbon Wheels - Mtbr.com


I sure hope everyone read this.


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## SS Hack (Jan 20, 2012)

ColinL said:


> I sure hope everyone read this.


Makes perfect sense - rims should be matched to tires more or less.


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## bholwell (Oct 17, 2007)

oldranger said:


> Sorry guys, I'm going back on my promise to leave the thread...I just couldn't pass up the latest comments with folks trying to 'school' bholwell on tire design.
> 
> Bholwell, I didn't come right out and ask you last year what rim width you would recommend for competitive DH racers using the Minion DHR2, Minion DHF, and High Roller tires...but I would love to know your opinion.


I designed the DHR2, High Roller II, and Shorty tire profiles on a rim with an inner width of 25mm. This isn't because I believe that a rim IW of 25mm is ideal for downhill riding/racing, but rather because that's what most people were running at the time. So if you don't stray too far from 25mm (say 30-32mm max) you'll likely be fine.

This quote by I9, though worded strangely, is very apt:


> Rims with exceptionally wide inner widths (for a given category) paired with a tire designed for much narrower rims, cause the cornering blocks on many tires to become so "square" that they no longer contact the trail surface in their the intended shear plane - causing a dramatic reduction in traction at the cornering limit or on of camber objects or sections of trail.


Once one leans in a flat corner at such an acute angle to the ground that the inside edge of the shoulder lug no longer makes good contact with the ground, cornering traction can dramatically drop off. So it makes sense that an XC tire that was designed on a 21mm IW rim will not perform well on a 40mm IW rim. In an ideal situation, the tire and rim should be designed to work together. The reality, however, is that severely limits your market. I can't imagine many people would want to buy a tire that was designed to work optimally on a rim with an inner width of A, when they own a rim with an inner width of B.

Could I envision rims with an inner width of 36 or 40mm eventually becoming the norm for downhill racing? Yes. But it will likely be a slow evolution due the the reason given above.


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## sherwin24 (Jul 23, 2010)

So what it comes down to is: wider is better in certain applications, and narrower is better in certain applications. More importantly, as bholwell points out along with I9, is matching tire to rim and the intended purpose.

At some point, wider rims, means wider tires, which means designing chainstays/seatstays and forks to allow for the extra width. This means longer cs/ss, higher bb, basically a geometry redesign. Which is fine, the industry has proven they can make 29" wheels work, so this is not a huge issue, and right now the rims are not wide enough to cause too much trouble with most bikes AFAIK.

Maybe that is the reason behind the "+"size tires and bikes to match those, to fill in the gap between xc/trail/enduro bikes and fat bikes?

Wider rims/ bigger tires means more weight. Right now I don't lack traction so I choose less weight. I could care less about ramming my bike into a curb and seeing if the wider rim makes it absorb better, I hop over the curb, and rocks when possible.


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## turbodog (Feb 28, 2004)

HillDancer said:


> A review with images of the devices used by Specialized to measure deflection: First Ride: Roval Traverse Fattie Wheels - Super Wide and Super Fast - Pinkbike
> [/url]


Wanted to jump in and point this out from the above article:



> The dozen or so journalists on hand provided a sample group for pinch flats and sidewall tears. There were only four, maybe five punctures over three full days of riding, three were sidewall injuries which required tubes. The rest were slow leaks which took longer than normal for the sealant to heal. Most took place on stage five, which began with a flat-out run over imbedded rocks. Looking back at the body of evidence, it appears that the survivability of a tire on the Traverse Fattie wheels is about the same as that same model fitted to a narrower rim.


So, this works out to one tire failure in 10 rider-days. Last time I checked, that is not acceptable if you're a tire buyer, but it's great if you sell tires lol. These failures come from riding low pressures, presumably for better traction and more compliance on rough terrain - the wide rim is needed to maintain tire stability at these lower pressures. This altogether makes the wide rim concept a false premise:

- If you're riding smoother terrain where there is little issue with sidewall flats, why are you riding low pressures? Higher pressures roll better and traction should be plentiful. Riding around on smooth terrain with wide rims and low tire pressures makes no sense. There is no need for an extra wide rim.

- If you're riding rough terrain where rim strikes and sidewall tears could be much more frequent, you need to increase tire pressures accordingly to keep your wheels and tires intact. So with this extra pressure, tire stability should not be a problem on normal width rims. There is no need for an extra wide rim.

I've only found one setup that let me do aggressive riding with very low pressures without sidewall tears or rapid rim damage - 2ply downhill tires with 500g motocross bike tubes - which provided padding for the rim and was extremely durable, though gradual rim damage did occur. Clearly not acceptable for trail riding with climbing involved.

IMHO, people gravitating to wider rims and low pressures are often under gunned in their tire selection for trail riding - too narrow tires with wimpy knobs or marginal rubber compounds. Selecting gripper tires that still have low rolling resistance and acceptable weight solves the traction issue without having to resort to unreasonably low pressure and extra wide rims to accommodate it.


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## Mountain Cycle Shawn (Jan 19, 2004)

sherwin24 said:


> So what it comes down to is: wider is better in certain applications, and narrower is better in certain applications. More importantly, as bholwell points out along with I9, is matching tire to rim and the intended purpose.
> 
> At some point, wider rims, means wider tires, which means designing chainstays/seatstays and forks to allow for the extra width. This means longer cs/ss, higher bb, basically a geometry redesign. Which is fine, the industry has proven they can make 29" wheels work, so this is not a huge issue, and right now the rims are not wide enough to cause too much trouble with most bikes AFAIK.
> 
> ...


This isn't all true. Most of the wide carbon rims are as light or lighter then the aluminum rims they are replacing. Just because the rims are getting wider, that doesn't meant the tire people will make the tires wider for these rims. Hopefully, they will make tires that work best for these rims. And, that doesn't necessarily mean that they have to be wider then they are now. Part of the reason wide rims work so good, is the fact that the tire isn't to wide for the rim. So, it doesn't make sense to just keep making the tires wider. And, right now, it seems that the narrower tires actually work better on wider rims. Then there is the weigh penelty, if tires get any wider. We don't want heavier tires.


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## sherwin24 (Jul 23, 2010)

Sorry, I meant wheels of the same material. a narrower carbon rim is still lighter than a wider carbon rim typically. It would seem that aluminum in over 30mm internal would become weight prohibitive by having to add more material to support the width. Carbon would definitely be the best for wider for that reason alone. Perhaps that will help bring the cost of carbon down some over time, as more companies spec carbon wheels just to give the masses a wide wheel with decent weight.

I am not against wide rims, been riding 25mm internal rims for a year and that was wide not long ago. But given the choice, I will take less weight over wider considering I don't feel I need any of the advantages wider offers given where and how I ride.


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## beanbag (Nov 20, 2005)

bholwell said:


> But it will likely be a slow evolution due the the reason given above.


I dunno, the bike industry was pretty ruthless in killing off the 26" wheel.


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## eb1888 (Jan 27, 2012)

sherwin24 said:


> Sorry, I meant wheels of the same material. a narrower carbon rim is still lighter than a wider carbon rim typically. It would seem that aluminum in over 30mm internal would become weight prohibitive by having to add more material to support the width. Carbon would definitely be the best for wider for that reason alone. Perhaps that will help bring the cost of carbon down some over time, as more companies spec carbon wheels just to give the masses a wide wheel with decent weight.
> 
> I am not against wide rims, been riding 25mm internal rims for a year and that was wide not long ago. But given the choice, I will take less weight over wider considering I don't feel I need any of the advantages wider offers given where and how I ride.


AC Wide Lightnings are 1569g and 29.3 inside aluminum. Roval has aluminum Fatties and Syntace has several sizes.

You can lace your own Chinese carbons with Dt 350 hubs for just over $600.


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## Legbacon (Jan 20, 2004)

Tires don't need to be wider but the knobs repositioned for the new profile. Wide doesn't have to mean heavy and a smaller tire can be used for a big footprint. Tire design may not be there yet but I'm sure it will the way things are going. I'm still using the old wide Flow EX.


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## cycloxer13 (Oct 27, 2014)

Travis Bickle said:


> Tires don't need to be wider but the knobs repositioned for the new profile.


Exactly. There is an opportunity to design a wider tread trail-category tire that has a similar casing width to today's tires. Then it could be mounted on a wider rim and still fit in today's frames and forks without clearance issues. I'd think that would be a winner.


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## cycloxer13 (Oct 27, 2014)

bholwell said:


> The sidewall of a bicycle tire does not handle vertical loads, as Mountain Cycle Shawn believes. The carcass of today's bicycle tires are so thin, it's simply not possible.


I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?


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## Mountain Cycle Shawn (Jan 19, 2004)

^ I think you're correct and I think we'll eventually see tires made for these wide rims. There are a lot of tires out there that work good with wide rims. But, they can get better. I mean what other industry has tires that are more than twice as wide as the rims?


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## cycloxer13 (Oct 27, 2014)

I'll tell you I have learned so much about tires and pressure this year as a result of my fat bike. I am not saying traditional mtb's should all go fat, but there is something to be said for the performance of wide tires and rims. I am actually really excited about the potential now that wide carbon rims are a reality. It really changes the game imho.


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## sherwin24 (Jul 23, 2010)

L


cycloxer13 said:


> I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?


Wouldn't a shorter sidewall invite more rim strikes unless tire pressure were increased? And wouldn't that negate some of the wide rim advantages?

Sorry for playing devils advocate, just trying to wrap my mind around what is real expectations with continuing to go wider.


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## cycloxer13 (Oct 27, 2014)

I don't mean shorter as in closer to the ground. I mean shorter in that the shape of the inflated tire will be more semi-circular and less pinched in at the bead like a light bulb. This would be more like a motorcycle tire. That's what I envision.


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## ColinL (Feb 9, 2012)

cycloxer13 said:


> I don't mean shorter as in closer to the ground. I mean shorter in that the shape of the inflated tire will be more semi-circular and less pinched in at the bead like a light bulb. This would be more like a motorcycle tire. That's what I envision.


Sounds heavy. There was quite recently some discussion of why MTB tires and wheels are different than motocross or dual-sport tires and wheels. I assure you all that was considered and some of it even tried since MX predates MTB.


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## cycloxer13 (Oct 27, 2014)

A wide carbon rim can be made pretty freakin light - probably even lighter than tire casing rubber. Mtb tire casing shape hasn't evolved much at all. This 'shape' if you will pre-dates carbon rims as well as tubeless systems. I think there are plenty of advances yet to come with a few tweaks.

I am not saying we should be riding a perfectly semi-circular tire as on a road motorcycle, but I do think we could get a lot closer to that and realize performance gains. In fact, the 4.6" tire on 90mm rim on my fat bike is a lot closer. I say just scale that down a bit to a summer XC version and you have a winner.


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## beanbag (Nov 20, 2005)

A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.


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## eb1888 (Jan 27, 2012)

beanbag said:


> A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.


Some tires don't work with wide rims because the tread cap becomes too squared when mounted on wide rims. The arc is inside.
But.
It's tough to discount future innovation once something like a wide rim being more readily available gives tire designers new opportunities.
Who knows what they will come up with?

With all the complexities of tire design and construction I feel it's incredibly unusual dumb luck that I am getting so much more performance from using tires in a way outside their original design perimeters.


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## cycloxer13 (Oct 27, 2014)

beanbag said:


> A bike tire will make a constant-radius arc from one bead to the other.


Is that shape the same or different on a wide rim? The point of the wide rim is to give the tire a better shape.


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## bholwell (Oct 17, 2007)

beanbag said:


> A bike tire is not like a car or motorcycle tire that has belts to maintain a certain cross sectional shape. A bike tire will make a constant-radius arc from one bead to the other.


Not exactly. Bicycle tires are definitely not like belted radial light truck or passenger tires. But they are quite similar to off-road motorcycle and non-belted bias ATV tires. The construction of a typical XC or AM bicycle tire is one body ply turned up over the beads. The turn-up is of adequate length to overlap in the center, underneath the tread. So you end up with two plies at the sidewall, and three plies underneath the tread.
If you'd like to see a picture:Basic Tire Construction | Maxxis USA

DH bicycle tires, off-road motorcycles tires, and non-belted bias ATV tires typically have two plies turned up over the beads, but the turn-ups are much shorter. In DH tires, the turn-ups end near the sidewall and tread junction, and in ATV tires the turn-ups are much lower.

All of the aforementioned tires have a bias construction, meaning that the direction of the cords within the body plies lie at an angle perpendicular to the direction of rotation. This angle is important because it gives the tire strength and sidewall stability. The greater the angle (if no angle is zero, or equivalent to a radial tire) the shorter the section height and the wider the section width of the tire. So a tire with a very high bias angle will have a flatter tread arc.


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## bholwell (Oct 17, 2007)

cycloxer13 said:


> Is that shape the same or different on a wide rim? The point of the wide rim is to give the tire a better shape.


It will be a different shape. But I don't agree that it's necessarily a better shape, especially if the rim is much wider than the tire design engineer intended.


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## cycloxer13 (Oct 27, 2014)

Blank sheet of paper. If you could match a new carbon rim to a new design tire for trail use, would you go wider than today's 'normal' 20mm rims?


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## bholwell (Oct 17, 2007)

beanbag said:


> I dunno, the bike industry was pretty ruthless in killing off the 26" wheel.


Yes, but that was for a different reason entirely, imo. There's a lot of performance overlap between the 26" and 27.5" wheel, and carrying the same models in both wheel sizes doesn't make a heck of a lot of sense. But one company can't simply say rims widths under 26mm are dead, and start designing all of their tires for rims with an internal width of 35mm. They'd be missing out on a lot of sales.


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## bholwell (Oct 17, 2007)

cycloxer13 said:


> Blank sheet of paper. If you could match a new carbon rim to a new design tire for trail use, would you go wider than today's 'normal' 20mm rims?


Absolutely. Although I think today's rims are actually wider than that. Not long ago, the typical XC rim was 17 or 19mm wide internally. Stan's rims became very popular, and their first model was the 355 which was 19mm wide internally. Now the Crest is 21mm wide. And when they release the next generation rims, they'll be even wider.

That's XC, and AM rims are even wider.

Where will we ultimately end up? I don't know. Weight will still be a consideration, because even though carbon rims can be made lighter, wider rims are still heavier, and unless the price of carbon comes way down the majority of rims will continue to be Al. But with the weight consideration aside, from a performance standpoint I think the optimal rim width is much closer to off-road motorcycle rims (as a percentage of rim width to tire section width) than where we are currently.


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## bholwell (Oct 17, 2007)

cycloxer13 said:


> I'm not a tire design engineer (but I am an ME), so correct me if I am wrong. I think tire shape when inflated is important. I think there is potential to design a tire with a wider tread pattern and shorter sidewalls that could be used in conjunction with a wide carbon rim. I would think this would work better than the traditional hourglass shape on a narrow aluminum rim. What do you think?


Yes, I agree. Doing so will result in better traction, particularly cornering performance.

But go too far in the extreme and you'll be extending your tread arc (relocating the shoulder lugs further apart, further down the sidewall), and this will add under-tread rubber, which will add weight and rolling resistance. Not good for XC.


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## cycloxer13 (Oct 27, 2014)

I agree 100%. I can't wait to see the first 'wide rim specific' trail tire. I'd imagine you could wrap the tread a littler wider and see a performance improvement.

My 4.6" Ground Controls are shaped a lot more like a motocross tire than a mountain bike tire. Of course they also weigh 1,500 grams each.


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## Yody (Jan 21, 2008)

Nobody remembers the michelin 2.8's and the sun doubles? Wide rims and tires have already been done. Great for straight line plowing or making up for lack of skill/correct body english. 

I think these ultra wide rims will go the way of the long travel 29r. All the intermediate riders are going to rant and rave and swear its the wave of the future. After awhile common sense will prevail and they will stilll be available but will not be dominating the market. Yes they will give you gobs of traction and be great in a straight line, but the extra weight and gyro affect will make them less nimble. Everyone wanted 29r Downhil bikes and 6" trail bikes, but how many of those do you see now?

Like everything, there is a middle ground. I think 25-30mm wide internal width is the ticket for most trail/all mountain/Dh bikes. Save the ultra wide rims for the guys on ridgid and single speeds where you need a big huge volume tire at low pressure to make up for a lack of suspension.


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## SS Hack (Jan 20, 2012)

Wide tires also provide tons of traction in corners and frankly I like the fact that they make up for my lack of skills - which a full suspension bike also does. I do ride a rigid SS and may have different priorities than some. I'm turning 45 in a couple days and don't mind "cheating" if it keeps my face off the ground.


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## Yody (Jan 21, 2008)

Well the current wide rims with normal tires do not make for tons of traction if you actually lean the bike over hard, as you roll right past those side knobs.....

I'm not completely discounting them. Im just saying that this new trend of people who think these wide rims and the best thing since suspension forks are not looking at this from all angles.


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## Lelandjt (Feb 22, 2008)

Yody said:


> Nobody remembers the michelin 2.8's and the sun doubles? Wide rims and tires have already been done. Great for straight line plowing or making up for lack of skill/correct body english.
> 
> I think these ultra wide rims will go the way of the long travel 29r. All the intermediate riders are going to rant and rave and swear its the wave of the future. After awhile common sense will prevail and they will stilll be available but will not be dominating the market. Yes they will give you gobs of traction and be great in a straight line, but the extra weight and gyro affect will make them less nimble. Everyone wanted 29r Downhil bikes and 6" trail bikes, but how many of those do you see now?
> 
> Like everything, there is a middle ground. I think 25-30mm wide internal width is the ticket for most trail/all mountain/Dh bikes. Save the ultra wide rims for the guys on ridgid and single speeds where you need a big huge volume tire at low pressure to make up for a lack of suspension.


^This. In skiing there is gear that helps intermediates do the best they ever have but holds back experts. There is gear that experts love but intermediates struggle with (I'm talking straight, stiff skis and stiff boots). Soft suspension and overly wide rims fit in the former category in the MTB world. Pros use firm suspension and rims that create a rounder tire shape. Pick the gear that works best for you and enjoy the ride. The "hype" would be believing that one thing is best for everyone and every condition.


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## Mountain Cycle Shawn (Jan 19, 2004)

Yody said:


> Well the current wide rims with normal tires do not make for tons of traction if you actually lean the bike over hard, as you roll right past those side knobs.....


That's your opinion. Pick the right tire and you can lean like hell on them and the silly grin you get on your face lasts till you hit the next corner, where the silly grin gets refreshed, and it just keeps going.


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## Deerhill (Dec 21, 2009)




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## cycloxer13 (Oct 27, 2014)

We need some new tires designed specifically for wide rims. Fortunately that is doable. It's a huge opportunity for the tire manufacturers. Everyone loves throwing on a fresh set of rubbers and even the most expensive tire don't break the bank.


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## Alias530 (Apr 1, 2013)

Is there any consensus on whether wide rims are the way to go?


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## IPunchCholla (Dec 8, 2013)

Alias530 said:


> Is there any consensus on whether wide rims are the way to go?


I don't think there is even a consensus on what the word wide means.


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## Alias530 (Apr 1, 2013)

My dilemma is--is going from 24->30mm internal going to be worth the ~9% weight penalty or should I stick with 24mm for trail riding?


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## manitou2200 (Apr 28, 2006)

Yody said:


> Well the current wide rims with normal tires do not make for tons of traction if you actually lean the bike over hard, as you roll right past those side knobs.....
> 
> I'm not completely discounting them. Im just saying that this new trend of people who think these wide rims and the best thing since suspension forks are not looking at this from all angles.





Lelandjt said:


> ^This. In skiing there is gear that helps intermediates do the best they ever have but holds back experts. There is gear that experts love but intermediates struggle with (I'm talking straight, stiff skis and stiff boots). Soft suspension and overly wide rims fit in the former category in the MTB world. Pros use firm suspension and rims that create a rounder tire shape. Pick the gear that works best for you and enjoy the ride. The "hype" would be believing that one thing is best for everyone and every condition.


There's definitely a sweet spot with rim width and appropriate tire selection and I feel that the sweet spot currently for most AM and DH tires is the 23-30mm rim width range. Most Important is tire selection based on rim width and intended use. I also like my 45mm wide rims with the 29+ tires on my rigid 29r! There is no one rim tire combo that works for everything and that's the bottom line!

It's no different with skis, bindings and boots. Big area days with big lines and big snow is best enjoyed with big skis and boots. If I'm logging big vert and long BC days I'm not going to ski my biggest skis or boots! Ski mountaineering objectives are even more select with the lightest setup to ski technical lines. There is no one is best for everything and don't kid yourself thinking that wide rims and big tires are good for do it all that won't happen.


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## ColinL (Feb 9, 2012)

cycloxer13 said:


> We need some new tires designed specifically for wide rims. Fortunately that is doable. It's a huge opportunity for the tire manufacturers. Everyone loves throwing on a fresh set of rubbers and even the most expensive tire don't break the bank.


Tires wider than 2.4 don't clear many mid travel forks and frames. So even if we are headed back towards 3", it can't happen overnight. And of course with fat bikes, there is an established limit. A 27.5 DH tire probably will not get near fat bike size.


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## cycloxer13 (Oct 27, 2014)

Alias530 said:


> My dilemma is--is going from 24->30mm internal going to be worth the ~9% weight penalty or should I stick with 24mm for trail riding?


Very tough question. I personally went with 25 internal until we get some wide-specific tires on the market. I was also worried about frame/fork clearances.


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## Alias530 (Apr 1, 2013)

cycloxer13 said:


> Very tough question. I personally went with 25 internal until we get some wide-specific tires on the market. I was also worried about frame/fork clearances.


I have a Pike on a Stumpjumper Evo, tons of clearance here. Typically run a DHF 29x2.5 up front and DHR2 29x2.3 or Ardent 29x2.25 in the back depending on the time of year.

I have no issues with traction as-is but if wide rims are as much of an improvement as tubeless or dropper posts were for me, I don't want to miss out on wide rims. But if they're just nonsense hype, I'd rather save the weight.


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## cycloxer13 (Oct 27, 2014)

You only need to take a few rides on a fat bike to understand what wide tires and rims can do - particularly if you are not racing and just trail/mtn riding for fun. Do you want ultimate grip or ultimate speed? It is a balance, of course. We are nowhere near optimal shape right now for traditional mtb's being ridden for fun, imho. Seriously, I laugh when I see 'normal' mtb rim/tire setups. They look so stupid and wrong.


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## Mountain Cycle Shawn (Jan 19, 2004)

cycloxer13 said:


> You only need to take a few rides on a fat bike to understand what wide tires and rims can do - particularly if you are not racing and just trail/mtn riding for fun. Do you want ultimate grip or ultimate speed? It is a balance, of course. We are nowhere near optimal shape right now for traditional mtb's being ridden for fun, imho. Seriously, I laugh when I see 'normal' mtb rim/tire setups. They look so stupid and wrong.


I say with wide rims you can have both. The lower pressures allow you to roll over rough terrain easier, allowing to to roll faster in a straight line. Maybe if you get into fat bikes that changes, I don't know. But, with a 40mm external width rim, with the proper tire, I don't see any negatives at all. I take that back, if your going from a narrow carbon to wide carbon, it'll be heavier. But, most people are going from a narrow aluminum rim to a wide carbon rim and saving some weight at the same time.


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> I say with wide rims you can have both. The lower pressures allow you to roll over rough terrain easier, allowing to to roll faster in a straight line. Maybe if you get into fat bikes that changes, I don't know. But, with a 40mm external width rim, with the proper tire, I don't see any negatives at all. I take that back, if your going from a narrow carbon to wide carbon, it'll be heavier. But, most people are going from a narrow aluminum rim to a wide carbon rim and saving some weight at the same time.


Like I've stated before I like my 30mm wide IW rims and I feel the current selection of tires for this rim width works pretty well. If you think that dropping tire pressure and increasing the area of contact patch is going to make you faster in a straight line then you're smoking crack because that's not anywhere near the truth. I do believe that lower tire pressures as a result of wider rim and tire combos can yield better handling, more control and make you faster overall but it's not by making your bike roll faster.


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## eb1888 (Jan 27, 2012)

manitou2200 said:


> Like I've stated before I like my 30mm wide IW rims and I feel the current selection of tires for this rim width works pretty well. If you think that dropping tire pressure and increasing the area of contact patch is going to make you faster in a straight line then you're smoking crack because that's not anywhere near the truth. I do believe that lower tire pressures as a result of wider rim and tire combos can yield better handling, more control and make you faster overall but it's not by making your bike roll faster.


Wide rim/lower pressure means more traction from tires that roll faster then what you used before but don't provide enough traction for your terrain when used with skinnier rims. Kind of roundabout but still the same faster rolling outcome. Like the rolling difference between a Racing Ralph you can use now when you had to use a slower rolling Nobby Nic on a skinny.

You could maybe pedal more too.


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## manitou2200 (Apr 28, 2006)

eb1888 said:


> Wide rim/lower pressure means more traction from tires that roll faster then what you used before but don't provide enough traction for your terrain when used with skinnier rims. Kind of roundabout but still the same faster rolling outcome. Like the rolling difference between a Racing Ralph you can use now when you had to use a slower rolling Nobby Nic on a skinny.


What??? That combo won't allow you to roll faster but you maybe able to carry more speed through twisty and rough terrain thus making you faster overall but it not because of lack of rolling resistance as you state. Your tire comparison is also a moot point larger contact patch through lower pressure yields higher rolling resistance. That's why you'll have more traction!


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## eb1888 (Jan 27, 2012)

Sounds like you need to do a little more testing.


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## Mountain Cycle Shawn (Jan 19, 2004)

Mountain Cycle Shawn said:


> I say with wide rims you can have both. The lower pressures allow you to roll over rough terrain easier, allowing to to roll faster in a straight line. Maybe if you get into fat bikes that changes, I don't know. But, with a 40mm external width rim, with the proper tire, I don't see any negatives at all. I take that back, if your going from a narrow carbon to wide carbon, it'll be heavier. But, most people are going from a narrow aluminum rim to a wide carbon rim and saving some weight at the same time.





manitou2200 said:


> What??? That combo won't allow you to roll faster but you maybe able to carry more speed through twisty and rough terrain thus making you faster overall but it not because of lack of rolling resistance as you state. Your tire comparison is also a moot point larger contact patch through lower pressure yields higher rolling resistance. That's why you'll have more traction!


Rough terrain is what I said. They sure don't make you roll or carry less speed.


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## manitou2200 (Apr 28, 2006)

eb1888 said:


> Sounds like you need to do a little more testing.


I don't think so buddy! Have you any experience with any of what we're talking about here or are you just theorizing this stuff you post?

I'll wager I have and had more wheel and tire combos than you'll ever ride in your lifetime.

I'm saying for most of the type of riding I do I think I'm faster on the wider rim tire combos with slightly lower pressure but it's not because of lower rolling resistance and it also not because of using a less aggressive tire like a Racing Ralph. LOL


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## eb1888 (Jan 27, 2012)

I'm faster on my 35/30 rim/tire combo because of better traction for sure. And I haven't noticed more rolling resistance from lower pressure and larger contact patch.. That's where our testing results seem to differ. 
But I haven't yet tried to go even faster on a tire I couldn't get enough traction from on a 21mm ArchEx but which was a slightly faster rolling tire than I am using now. I will try that combo, or actually a Thunder Burt instead of a Racing Ralph when the snow is gone this season. And on the pedaling, I can probably go faster with my present combo because of the increased traction by just pedaling more and taking more speed into the corners.


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## ebenke (Sep 1, 2008)

9%? Just how many ounces are you talking? Go with a light carbon build and you won't be gaining any weight.


EBenke


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## Alias530 (Apr 1, 2013)

ebenke said:


> 9%? Just how many ounces are you talking? Go with a light carbon build and you won't be gaining any weight.
> 
> EBenke


I did the percentage in my head, but it turns out it's actually 7.7%

420g for the 30mm internal width rim or 390g for the 24mm internal width rim. Both Light Bicycle carbon rims. Compared to the whole bike and the rider and everything, 2 ounces is nothing, but it is on the rim, which arguably matters most.

I knew a guy who used to drag race and he would take out his CD player, empty his coin tray, etc to get a faster time and that's WAY less in proportion to a car so it's not THAT crazy to at least discuss the difference of 60g of rim weight.


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## cycloxer13 (Oct 27, 2014)

The Nextie NXT29H06 (25mm ID) weigh 380 grams. That is pretty light for a moderately wide rim.


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## Mountain Cycle Shawn (Jan 19, 2004)

A lot of LB breakages out there.


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## rfxc (Oct 18, 2004)

I'm considering the LB 38mm rims, 31.6mm internal... But wondering if that's too wide for a 2.25 ardent.


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## Alias530 (Apr 1, 2013)

rfxc said:


> I'm considering the LB 38mm rims, 31.6mm internal... But wondering if that's too wide for a 2.25 ardent.


I hope not... I'm about to order 30mm internal width rims and I run an Ardent 2.25 in the back in the summer.


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## meltingfeather (May 3, 2007)

manitou2200 said:


> larger contact patch through lower pressure yields higher rolling resistance.


This is incorrect.
In general overall rolling efficiency goes up (resistance goes down) as pressure goes down on rough surfaces.


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## Alias530 (Apr 1, 2013)

meltingfeather said:


> This is incorrect.
> In general overall rolling efficiency goes up (resistance goes down) as pressure goes down on rough surfaces.


There has to be a point where the curve changes directions though... if pressure gets too low, you're fighting the sidewall constantly crumpling.

I ran my cross bike at the max recommended pressure for the tire on the stock rims... when I went wide (17mm stock - > 22mm... wide for a CX bike anyway ), I ran 5psi less but the tire didn't look nearly-flat under my heavy self lol


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## Brian Damage (Apr 15, 2007)

Alias530 said:


> I hope not... I'm about to order 30mm internal width rims and I run an Ardent 2.25 in the back in the summer.


I run an Ardent 2.25 on my LB 35-O/30-I rim no problem. I do think the 2.25" ardent is too narrow for my Derby 40-O rim however although I know some guys who run 2.25 on their Derbys.


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## Brian Damage (Apr 15, 2007)

Mountain Cycle Shawn said:


> A lot of LB breakages out there.


I can attest to 2 broken LB rims.. The first one of their hooked older versions they replaced no questions asked (I paid ~$50 for shipping). The 2nd they offered me a $15 credit on my next order. To be fair I dinged a rock pretty hard, but I don't think it should have cracked through the way it did. On principle I may not be able to order from LB again. Won't go back to AL rims tho.


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## rfxc (Oct 18, 2004)

Brian Damage said:


> I can attest to 2 broken LB rims.. The first one of their hooked older versions they replaced no questions asked (I paid ~$50 for shipping). The 2nd they offered me a $15 credit on my next order. To be fair I dinged a rock pretty hard, but I don't think it should have cracked through the way it did. On principle I may not be able to order from LB again. Won't go back to AL rims tho.


Similar story. I've had 6 LB rims in my household, broke two racing enduro/ dh at keystone in 2013 (prior to their hookless offerings). Learned my lesson. 
I'll always have an alum set around for my roughest days, but the carbon stiffness and weight is so addictive...


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## ColinL (Feb 9, 2012)

And the air pressure you were running when you all broke your LB rims was...?


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## Brian Damage (Apr 15, 2007)

ColinL said:


> And the air pressure you were running when you all broke your LB rims was...?


Lower than it should have been :nono:
Both were rear wheels. I usually run 30 psi but figure I was down around 25 when it happened


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## JLF1200 (Sep 16, 2009)

This thread is folding back on itself. About 75 posts ago I said I was used to seeing carbon rims-- especially LB rims-- blow up at races more often than alloy, and that I'd had quite a few gravity riders (DH/enduro) who had tried very-wide rims mention to me that they closed down the shoulder lug spacing on their tires. Then some of the typical MTBR math police swarmed me because I couldn't "prove" anything I was saying, and because "racers don't know anything about the bikes they ride" compared to engineers (presumably, these were engineers). 

Now we've got a tire designer and a wheel manufacturer confirming the importance of "rim size to tire" relationship, as well as the shoulder lug orientation issue if your rim is too wide, and a bike racer mentioning their LB carbon rims blew up easier than they should have.

I guess we'll wait for the all-knowing ones to chime in and let us all know how wrong we are, again.


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## Yody (Jan 21, 2008)

JLF1200 said:


> This thread is folding back on itself. About 75 posts ago I said I was used to seeing carbon rims-- especially LB rims-- blow up at races more often than alloy, and that I'd had quite a few gravity riders (DH/enduro) who had tried very-wide rims mention to me that they closed down the shoulder lug spacing on their tires. Then some of the typical MTBR math police swarmed me because I couldn't "prove" anything I was saying, and because "racers don't know anything about the bikes they ride" compared to engineers (presumably, these were engineers).
> 
> Now we've got a tire designer and a wheel manufacturer confirming the importance of "rim size to tire" relationship, as well as the shoulder lug orientation issue if your rim is too wide, and a bike racer mentioning their LB carbon rims blew up easier than they should have.
> 
> I guess we'll wait for the all-knowing ones to chime in and let us all know how wrong we are, again.


Lol I love your breakdown. I would give rep but already gave it to you in the beginning of post


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## cycloxer13 (Oct 27, 2014)

I think wide carbon rims are here to stay and I think they will only get better. I'm just waiting for wide-design tires to hit the market. We're just going through some growing pains. There is still so much potential and room for improvement

Fwiw, I am running carbon rims on my road bike, my mtn bike, my fat bike, and I used to have them on my cyclocross race bike. Other than a broken Spinergy circa 2005, I have yet to break any of the newer carbon offerings. I do weigh 142#, but I don't see myself ever riding an aluminum rim again. The carbon offerings simply superior, imho.


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## JLF1200 (Sep 16, 2009)

cycloxer13 said:


> I think wide carbon rims are here to stay and I think they will only get better. I'm just waiting for wide-design tires to hit the market. We're just going through some growing pains. There is still so much potential and room for improvement
> 
> Fwiw, I am running carbon rims on my road bike, my mtn bike, my fat bike, and I used to have them on my cyclocross race bike. Other than a broken Spinergy circa 2005, I have yet to break any of the newer carbon offerings. I do weigh 142#, but I don't see myself ever riding an aluminum rim again. The carbon offerings simply superior, imho.


I'd say you're right. But the thread was originally started to discuss the viability of extra-wide rims in DH racing-- curious that we don't see them anywhere, from the World Cup on down. This suggests that there are limits to the "awesomeness" that virtually all of the average joe consumers report about switching to Derby or LB rims. I, among others on the thread, offered some reasons why the rims just don't work for riders who, on average, go faster and demand more from their tires. Those ideas were countered with shouts of "BLASPHEMY!" and other such sore-ego outrage, along with "bike racers don't know much about their own bikes" as an alternative explanation of wide rim absence in DH. So the opposing school of thought basically held that the world's fastest downhillers, and their mechanics, and the engineers who support them, and the corporate component firms invested in their riders winning at all costs, were all clueless. I'm just reiterating this in case the trolls return, and so newcomers to the thread understand why the thread seems to have a suspicious tone even while the wide rim trend has been improving the stoke for the vast majority of consumers who buy in.


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## JLF1200 (Sep 16, 2009)

... Oh, and my personal favorite was the explanation that DH racers are slow to adopt new technologies.


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## ebenke (Sep 1, 2008)

I wouldn't touch LB with a 10' pole, way too many failures. I went with Derby's and saved weight going with Sapim CX Ray Spokes.


EBenke


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## manitou2200 (Apr 28, 2006)

meltingfeather said:


> This is incorrect.
> In general overall rolling efficiency goes up (resistance goes down) as pressure goes down on rough surfaces.


Sorry but this is so far off its funny! All things being equal in a straight line as you lower air pressure in a tire and increase the contact patch, rolling resistance will increase. There isn't any way that you can explain the contrary!

I stated earlier that given terrain changes with twists, turns and berms and direction changes you will most likely be faster because of the increase in traction but it will not be because of lower rolling resistance. I do know this from personal experience with repeats over the same terrain.


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## manitou2200 (Apr 28, 2006)

Alias530 said:


> I hope not... I'm about to order 30mm internal width rims and I run an Ardent 2.25 in the back in the summer.





Brian Damage said:


> I run an Ardent 2.25 on my LB 35-O/30-I rim no problem. I do think the 2.25" ardent is too narrow for my Derby 40-O rim however although I know some guys who run 2.25 on their Derbys.


The Ardents are a high volume tire but given a 30+mm IW the 2.25 size is less ideal as a front tire. It's ok as a rear tire but you should really run the 2.4 Ardent or another HV 2.35 tire like the Hans Damf, Trail King or Nobby Nic on the front.


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> A lot of LB breakages out there.


2 obvious things

1. You need to know how they many they sell - there have been 6 LBS, 2 nextie , and 2 enves bought in my riding group in 2014, one broken LB rim by the most aggressive rider in the group. Never even seen a derby or ibis rim anywhere , not even in big event races.

2. The guy who cracked a rim, was also running 5psi than he used to with alu rims.

So the big freaking pink elephant in the room - is stop telling people they can run super low pressures on their carbon rims. Dog knows how many rims have been busted because of the rubbish advice that comes out of forums such as these.

Widish rims are awesome, but they don't suspend physics, even for derby


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## Mountain Cycle Shawn (Jan 19, 2004)

JLF1200 said:


> I'd say you're right. But the thread was originally started to discuss the viability of extra-wide rims in DH racing-- curious that we don't see them anywhere, from the World Cup on down. This suggests that there are limits to the "awesomeness" that virtually all of the average joe consumers report about switching to Derby or LB rims. I, among others on the thread, offered some reasons why the rims just don't work for riders who, on average, go faster and demand more from their tires. Those ideas were countered with shouts of "BLASPHEMY!" and other such sore-ego outrage, along with "bike racers don't know much about their own bikes" as an alternative explanation of wide rim absence in DH. So the opposing school of thought basically held that the world's fastest downhillers, and their mechanics, and the engineers who support them, and the corporate component firms invested in their riders winning at all costs, were all clueless. I'm just reiterating this in case the trolls return, and so newcomers to the thread understand why the thread seems to have a suspicious tone even while the wide rim trend has been improving the stoke for the vast majority of consumers who buy in.


I think one reason is that DH tires are much heavier and stronger then the light tires that all of us trail and AM riders use. Maybe that type of tire just doesn't need a wide rim, and maybe they just don't work any better with wide rims.


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## cycloxer13 (Oct 27, 2014)

I think the DH'ers are worried about impact strength. DH'ers also benefit the least from a light rim, though I think they could benefit the most from a wie rim with a matching tire. It takes time to perfect new technologies. Consider what you could buy for mtb carbon rims only 3 years ago - not much. The pace of change is actually quite rapid in this space.


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## meltingfeather (May 3, 2007)

manitou2200 said:


> Sorry but this is so far off its funny! All things being equal in a straight line as you lower air pressure in a tire and increase the contact patch, rolling resistance will increase. There isn't any way that you can explain the contrary!
> 
> I stated earlier that given terrain changes with twists, turns and berms and direction changes you will most likely be faster because of the increase in traction but it will not be because of lower rolling resistance. I do know this from personal experience with repeats over the same terrain.


You need to educate yourself.
This topic has been discussed exhaustively on this forum. The main mechanism is that lower pressure allows the bike and rider to roll "through" irregularities in the trail rather than firmer tires causing bumps in the trail to actually lift the rider and bike (using momentum). Lifting a 150-lb. bike+rider and not recovering that momentum robs quite a bit more energy than the hysteresis of the tire deflection, which is obvious once you look at the work that has been done on this topic.
Then again, if you're a disciple of your own opinion and think your experience establishes the laws of the universe, you will be impermeable to facts.


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## Haymarket (Jan 20, 2008)

manitou2200 said:


> Sorry but this is so far off its funny! All things being equal in a straight line as you lower air pressure in a tire and increase the contact patch, rolling resistance will increase. There isn't any way that you can explain the contrary!
> 
> I stated earlier that given terrain changes with twists, turns and berms and direction changes you will most likely be faster because of the increase in traction but it will not be because of lower rolling resistance. I do know this from personal experience with repeats over the same terrain.


It may be counter intuitive, but it is well established that on rough terrain, rolling resistence is REDUCED with lower pressures. You can Google it, but that is not arguable as it has been exhaustively tested.


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## IPunchCholla (Dec 8, 2013)

Haymarket said:


> It may be counter intuitive, but it is well established that on rough terrain, rolling resistence is REDUCED with lower pressures. You can Google it, but that is not arguable as it has been exhaustively tested.


First. I run lower pressures 20F/24R and I believe that they give me both more traction and less rolling resistance. But, I can only find the one study by Schwalbe, which is indicative, but hardly conclusive. Are there other studies? Everything else is anecdotal, and while I agree with it I would hardly call it exhaustively tested if Schwalbe's is the only one.


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## ColinL (Feb 9, 2012)

meltingfeather said:


> You need to educate yourself.
> This topic has been discussed exhaustively on this forum. The main mechanism is that lower pressure allows the bike and rider to roll "through" irregularities in the trail rather than firmer tires causing bumps in the trail to actually lift the rider and bike (using momentum). Lifting a 150-lb. bike+rider and not recovering that momentum robs quite a bit more energy than the hysteresis of the tire deflection, which is obvious once you look at the work that has been done on this topic.
> Then again, if you're a disciple of your own opinion and think your experience establishes the laws of the universe, you will be impermeable to facts.


I could see this being true for a rigid bike.

Is it actually true for a full suspension bike? It seems evident that the suspension or lack thereof in the tire is several orders of magnitude less than the (usually air) springs and dampers on the bike.


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## BikeIntelligencer (Jun 5, 2009)

Have you tried raising the psi????



JLF1200 said:


> This thread is folding back on itself...


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## meltingfeather (May 3, 2007)

JLF1200 said:


> I'd say you're right. But the thread was originally started to discuss the viability of extra-wide rims in DH racing-- curious that we don't see them anywhere, from the World Cup on down. This suggests that there are limits to the "awesomeness"


There are half-witted "arguments" on both sides of this issue.
The contention that the fact that wide rims are not prevalent right now on the World Cup circuit means there is some fundamental performance reason being one.
I don't have an opinion on what works for somebody else on their bike, but I do respect the opinions of people who know what they're talking about, and not those of trolls like the OP who have an axe to grind and pick some topic on MTBR a as their outlet.


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## turbodog (Feb 28, 2004)

JLF1200 said:


> This thread is folding back on itself. About 75 posts ago I said I was used to seeing carbon rims-- especially LB rims-- blow up at races more often than alloy, and that I'd had quite a few gravity riders (DH/enduro) who had tried very-wide rims mention to me that they closed down the shoulder lug spacing on their tires. Then some of the typical MTBR math police swarmed me because I couldn't "prove" anything I was saying, and because "racers don't know anything about the bikes they ride" compared to engineers (presumably, these were engineers).
> 
> Now we've got a tire designer and a wheel manufacturer confirming the importance of "rim size to tire" relationship, as well as the shoulder lug orientation issue if your rim is too wide, and a bike racer mentioning their LB carbon rims blew up easier than they should have.
> 
> I guess we'll wait for the all-knowing ones to chime in and let us all know how wrong we are, again.


I'm with you on this. Very wide rims came and went 15 years ago. Interesting to see the trend being recycled.


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## oldranger (Apr 14, 2011)

meltingfeather said:


> There are half-witted "arguments" on both sides of this issue.
> The contention that the fact that wide rims are not prevalent right now on the World Cup circuit means there is some fundamental performance reason being one.
> I don't have an opinion on what works for somebody else on their bike, but I do respect the opinions of people who know what they're talking about, and not those of trolls like the OP who have an axe to grind and pick some topic on MTBR a as their outlet.


Geesh. Nice personal attack.

OK, then tell us why YOU think there are no rims wider than 27mm internal width on the World Cup DH circuit, or on any of the premium DH bike specs.

I don't have an axe to grind. I don't even hide behind my member name. I just don't see the reason to experiment with my $$ on expensive wide rims and wanted to read some opinions.


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## oldranger (Apr 14, 2011)

Melting Feather, you've been attacking me and taking this thread off topic for a year. Please take your opinions elsewhere. I don't see any information in your profile that suggests you have credibility on this topic. You haven't indicated that you have a DH bike or any DH riding experience. Experience riding your single speed around Austin or puttering around your local trails on your hei-hei 29er does not apply here.

I didn't start this off with a half-witted argument. Here is how I clarified myself on day one of this thread, over a year ago:



oldranger said:


> That said, after a day of interesting comments, I'd like to restate my hypothesis because I think some of you missed it: *the ideal rim width for DH tires on the market today is 23mm - 25mm of internal width*. I started this thread in hopes there would be attempts to prove or disprove it&#8230;which in turn, help me make a good decision on a pair of wheels for my DH bike. I recognize it's not a well justified hypothesis, and the word "ideal" oversimplifies things&#8230;but the point I'm making has not been disproven in this thread. On the contrary, a tire designer seems to (indirectly) support it and that is the only professional opinion so far on the thread. Maybe I should try to elaborate a bit on what I mean by ideal: I mean compatible with, and works optimally in conjunction with a conventional DH tire (2.3-2.5 DH casing) to provide the best possible traction for the rider without adversely impacting speed or durability. "Ideal" for DH is not: wide enough to enable dramatically low psi so the rider doesn't perceive slip on rocks and roots and such. Or worse&#8230;so the rider can sit down comfortably.
> 
> Let's not dumb this down. I threw this topic out in a forum dedicated to Wheels & Tires. This discussion isn't about preference, or Recreation vs. Racing, or how something feels. I consider myself a recreational rider. But frankly folks - if you are a "recreational rider" sitting on a $4-8K DH bike&#8230;you're sitting on a sophisticated, carefully spec'd piece of equipment. And most of you try to go fast (I hope). Me personally: I don't want to ignorantly do the equivalent of throwing a big ass set of Dubs on a BMW M3 just because of some hype around 'WIDE is BETTER' and manufacturers like I9, Atomlab, Spank, etc. wanting to sell us those things. It is a common play to penetrate a market with gimmicky products that owners can't find as OE on some car or truck or gun or bike - under the premise it is better.


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## meltingfeather (May 3, 2007)

oldranger said:


> Geesh. Nice personal attack.


:skep:



oldranger said:


> OK, then tell us why YOU think there are no rims wider than 27mm internal width on the World Cup DH circuit, or on any of the premium DH bike specs.


I'm not sure... it could be a number of things.
Spesh team riders are rolling 30mm Traverse SL Fatties on enduro bikes (bikes they have ridden in World Cup DH events), which is new this year, so it could be a matter of time, among the other things.
Unfortunately there's so much butt hurt around this that I'm skeptical that any productive discussion can be salvaged.



oldranger said:


> I don't have an axe to grind. I don't even hide behind my member name.


huh?


oldranger said:


> I just don't see the reason to experiment with my $$ on expensive wide rims and wanted to read some opinions.


You are the one who started a thread with a belligerent title and already established opinion. It looks like it has stayed true to the way it started.
To now say all you wanted was to solicit opinions so you can make an informed decision with your hard earned chee$e is a joke.
Who the hell is telling you what to do with your money?
I must have missed that thread.


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## Le Duke (Mar 23, 2009)

ColinL said:


> I could see this being true for a rigid bike.
> 
> Is it actually true for a full suspension bike? It seems evident that the suspension or lack thereof in the tire is several orders of magnitude less than the (usually air) springs and dampers on the bike.


There was an article a while back, maybe on Pinkbike, in which Schwalbe and other tire manufacturers did some high-def, high-rate video of their DH tires and the suspension linkage in action.

There is a significant delay between when your tire goes from its full radius to complete compression, and when the suspension starts to react, mostly due to stiction. Meaning, they determined that tires are hitting rocks, the rock is fully compressing the tire, and starting to rebound, before the suspension even begins to move.


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## Le Duke (Mar 23, 2009)

manitou2200 said:


> Sorry but this is so far off its funny! All things being equal in a straight line as you lower air pressure in a tire and increase the contact patch, rolling resistance will increase. There isn't any way that you can explain the contrary!
> 
> I stated earlier that given terrain changes with twists, turns and berms and direction changes you will most likely be faster because of the increase in traction but it will not be because of lower rolling resistance. I do know this from personal experience with repeats over the same terrain.


Sorry, but scientific experiments would contradict your statement.

Wider is faster! | Schwalbe North America


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## ColinL (Feb 9, 2012)

pharmaboy said:


> 2 obvious things
> So the big freaking pink elephant in the room - is stop telling people they can run super low pressures on their carbon rims. Dog knows how many rims have been busted because of the rubbish advice that comes out of forums such as these.
> 
> Widish rims are awesome, but they don't suspend physics, even for derby


I completely agree. Others can disagree, but when/if they break a rim, they probably should try more air pressure in the tire afterwards. The air you need is different.



Le Duke said:


> Sorry, but scientific experiments would contradict your statement.
> 
> Wider is faster! | Schwalbe North America


I had not seen that, thank you. The summary is quite vague; we don't know what consists of 'road' as you would think that it's not just asphalt or concrete, most gravel roads probably behave the same as well. What about a groomed BMX track?

But on singletrack, we use the least air pressure that keeps the rim from making contact with roots and rocks, and if tubeless, not burping air when cornered hard. That's going to give the most traction and the least rolling resistance.

People get into trouble when they guess wrong on what's the least pressure they can run, and they damage or destroy rims.


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## meltingfeather (May 3, 2007)

ColinL said:


> I completely agree. Others can disagree, but when/if they break a rim, they probably should try more air pressure in the tire afterwards. The air you need is different.


This is far too rational. :arf:



ColinL said:


> I had not seen that, thank you. The summary is quite vague; we don't know what consists of 'road' as you would think that it's not just asphalt or concrete, most gravel roads probably behave the same as well. What about a groomed BMX track?


Here is a more complete paper.
In general the smoother the surface the less the effect until some roughness tipping point where the relationship flips (resistance decreases with increasing pressure).



ColinL said:


> But on singletrack, we use the least air pressure that keeps the rim from making contact with roots and rocks, and if tubeless, not burping air when cornered hard. That's going to give the most traction and the least rolling resistance.


Another limiting factor for a lot of riders is squirm in corners.



ColinL said:


> People get into trouble when they guess wrong on what's the least pressure they can run, and they damage or destroy rims.


Or worse, get injured. When the penalty for failure is high, approach with caution (IMO).


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## Le Duke (Mar 23, 2009)

More:

http://www.mtbonline.co.za/downloads/Rolling_Resistance_Eng_illustrated.pdf

Edit: That M-Fer MF beat me to it.


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## Le Duke (Mar 23, 2009)

There is a reason that many World Cup XC racers are running tubulars: They can run lower pressure with very little to no chance of a pinch flat, and little chance of rim damage.

If the most competitive mountain bike racers in the world are running 1.5bar for speed and grip purposes, perhaps there's something to it.


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## Yody (Jan 21, 2008)

Le Duke said:


> There is a reason that many World Cup XC racers are running tubulars: They can run lower pressure with very little to no chance of a pinch flat, and little chance of rim damage.
> 
> If the most competitive mountain bike racers in the world are running 1.5bar for speed and grip purposes, perhaps there's something to it.


And theyre also running their seats up their arse, should I do that as well?


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## Le Duke (Mar 23, 2009)

Proper seat height.

They don't use droppers because they feel they don't need them. You may run your seat low because you think it looks cool; they run what is proven to allow them the most comfort while producing the most power. 

It should be noted that many/most of them run droppers on their trail/AM bikes.


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## Mountain Cycle Shawn (Jan 19, 2004)

meltingfeather said:


> I don't have an opinion on what works for somebody else on their bike, but I do respect the opinions of people who know what they're talking about, and not those of trolls like the OP who have an axe to grind and pick some topic on MTBR a as their outlet.


This behavior like that of the OP usually stems from the fact that they can't or don't want to keep spending the money to constantly upgrade their bike with better technology. Along with the fact that they have never tried or even seen what they are all against. These threads pop up everytime some big change comes along. 99% of the time 99% of us end up embracing the change in the long run. The other 1% are still riding rigid bikes with long stems, rim brakes and steep geometries.


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## Mountain Cycle Shawn (Jan 19, 2004)

Le Duke said:


> Proper seat height.
> 
> They don't use droppers because they feel they don't need them. You may run your seat low because you think it looks cool; they run what is proven to allow them the most comfort while producing the most power.
> 
> It should be noted that many/most of them run droppers on their trail/AM bikes.


Yeah, who needs a high seat height on a DH run?


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## turbodog (Feb 28, 2004)

Le Duke said:


> There is a reason that many World Cup XC racers are running tubulars: They can run lower pressure with very little to no chance of a pinch flat, and little chance of rim damage.
> 
> If the most competitive mountain bike racers in the world are running 1.5bar for speed and grip purposes, perhaps there's something to it.


XC bikes these days might as well be hybrids.....oh wait.

XC Bike Checks: 4 World Cup Race Machines - Pinkbike


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## Le Duke (Mar 23, 2009)

turbodog said:


> XC bikes these days might as well be hybrids.....oh wait.
> 
> XC Bike Checks: 4 World Cup Race Machines - Pinkbike


How does it feel to know that you'd get stomped into the ground by guys on "hybrids"?


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## cycloxer13 (Oct 27, 2014)

turbodog said:


> XC bikes these days might as well be hybrids.....oh wait.


Wait until they start showing up with wide carbon rims and even lighter tires...it's coming...hybwide


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## rfxc (Oct 18, 2004)

manitou2200 said:


> The Ardents are a high volume tire but given a 30+mm IW the 2.25 size is less ideal as a front tire. It's ok as a rear tire but you should really run the 2.4 Ardent or another HV 2.35 tire like the Hans Damf, Trail King or Nobby Nic on the front.


I'm considering a minion dhf 2.3 as a front tire-- hoping it will work on the 31.6 internal rim from LB.


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## manitou2200 (Apr 28, 2006)

meltingfeather said:


> You need to educate yourself.
> This topic has been discussed exhaustively on this forum. The main mechanism is that lower pressure allows the bike and rider to roll "through" irregularities in the trail rather than firmer tires causing bumps in the trail to actually lift the rider and bike (using momentum). Lifting a 150-lb. bike+rider and not recovering that momentum robs quite a bit more energy than the hysteresis of the tire deflection, which is obvious once you look at the work that has been done on this topic.
> Then again, if you're a disciple of your own opinion and think your experience establishes the laws of the universe, you will be impermeable to facts.


It's the other way around dude! Either that or your reading comprehension is very poor. You seem to be referring to the dynamic qualities of what lower air pressure can do for the handling and speed carried on a mountain bike.

What I stated very clearly is that lower pressure as opposed to higher pressure in the same tire will create a larger contact patch. That larger contact patch will also create higher rolling resistance not lower rolling resistance!

I do agree that the dynamic handling of most mountain bikes will be enhanced with appropriately matched rim width and tire combos inflated to an optimal psi be that lower than an over-inflated tire on the same rim. I've never stated otherwise in this thread. Optimal being the key word here whether it relates to the matching of rim width and tire size or proper inflation.


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## manitou2200 (Apr 28, 2006)

Haymarket said:


> It may be counter intuitive, but it is well established that on rough terrain, rolling resistence is REDUCED with lower pressures. You can Google it, but that is not arguable as it has been exhaustively tested.


Like I stated in my reply to MF, you also need to work on the reading comprehension!


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## meltingfeather (May 3, 2007)

manitou2200 said:


> It's the other way around dude!


Stop digging yourself into a hole and spend 5 minutes reading the links provided.
you're wrong.
it's been beat to death here on mtbr.
simple.


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## J.B. Weld (Aug 13, 2012)

manitou2200 said:


> Like I stated in my reply to MF, you also need to work on the reading comprehension!


It doesn't matter how good your reading comprehension is if you're reading the wrong information.


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## Mountain Cycle Shawn (Jan 19, 2004)

meltingfeather said:


> Stop digging yourself into a hole and spend 5 minutes reading the links provided.
> you're wrong.
> it's been beat to death here on mtbr.
> simple.


+100%


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## Haymarket (Jan 20, 2008)

manitou2200 said:


> It's the other way around dude! Either that or your reading comprehension is very poor. You seem to be referring to the dynamic qualities of what lower air pressure can do for the handling and speed carried on a mountain bike.
> 
> What I stated very clearly is that lower pressure as opposed to higher pressure in the same tire will create a larger contact patch. That larger contact patch will also create higher rolling resistance not lower rolling resistance!
> 
> I do agree that the dynamic handling of most mountain bikes will be enhanced with appropriately matched rim width and tire combos inflated to an optimal psi be that lower than an over-inflated tire on the same rim. I've never stated otherwise in this thread. Optimal being the key word here whether it relates to the matching of rim width and tire size or proper inflation.


You really should read up on it...counter intuitive and different than resistance on smooth surfaces, but to argue something that has been widely disproven makes yourself look a little silly. Do a search or read the links. Effective rolling resistance is lower at lower pressures on rough terrain. Period.


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## pharmaboy (Nov 11, 2005)

Haymarket said:


> You really should read up on it...counter intuitive and different than resistance on smooth surfaces, but to argue something that has been widely disproven makes yourself look a little silly. Do a search or read the links. Effective rolling resistance is lower at lower pressures on rough terrain. Period.


Im not sure the "period" is really necessary . While it seems to be the case, there hasn't been a re run of the study to reproduce the results, and it wasn't the best quality study ever. Given there is so little info , we go with what we have, but it's a long way from a fact.


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## aerius (Nov 20, 2010)

Le Duke said:


> Sorry, but scientific experiments would contradict your statement.
> 
> Wider is faster! | Schwalbe North America


Fat bikes, clearly, are the future of all racing disciplines!


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> Im not sure the "period" is really necessary . While it seems to be the case, there hasn't been a re run of the study to reproduce the results, and it wasn't the best quality study ever. Given there is so little info , we go with what we have, but it's a long way from a fact.


The "period" was really necessary!!


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## cycloxer13 (Oct 27, 2014)

aerius said:


> Fat bikes, clearly, are the future of all racing disciplines!


No, but if you spend some time riding one, you may be enlightened by what you can do with wide tires and wide rims.

What a lot of people are missing is that most of us are not racing. We are out there trying to have fun and enjoy mountain biking whenever we have a chance to play. Wide tires and wide rims can enhance that experience, imho, especially for the average joey who maybe doesn't have Absalon lungs nor Peat skills.

Look, I used to race XC at a very high level. It was awesome. I loved it. However, I wouldn't want to roll around on one of those rigs to go rip some trails with my buds and my dog. XC race rigs may be fast, but they also kinda suck, are uncomfortable, and have their trail capability limits. This fall I purposely rode my Fatboy on all group rides because I wanted to understand how the bike performed. It was an enlightening experience. I just kept thinking, damn, if we could just scale down this tire/rim combo and throw it on a FS trail bike, it would be one hell of fun ride - a true winner.


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## Flyin_W (Jun 17, 2007)

manitou, Regardless of the Schwalbe study that (you haven't read) insists lower pressure / bigger volume are faster in rough terrain. 
Watch any XC race to see who flats. Usually it's not the big guy with the 2.3 / 2.4 tire, more often it's the light weight pushing a 2.0 /2.1 tire. 
Simple fact is very, very few people who flat ever win a race. And if just riding rough terrain who the heck wants to repair a flat?
Once you try a big volume tubeless tire, you'll (stop arguing) and not go back.


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## cycloxer13 (Oct 27, 2014)

Flyin_W said:


> Once you try a big volume tubeless tire, you'll (stop arguing) and not go back.


Haha exactly. I easily envision trail bike tires creeping up more towards 3" on wide rims. I think once the wheel-tire system is optimized the weight will either equal or even go below what most of us are riding today.


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## Mountain Cycle Shawn (Jan 19, 2004)

cycloxer13 said:


> Haha exactly. I easily envision trail bike tires creeping up more towards 3" on wide rims. I think once the wheel-tire system is optimized the weight will either equal or even go below what most of us are riding today.


I don't think they'll get any fatter for trail use. The whole idea is not to have the tire so out of proportion with the rim. It's not that wide rims are better. The size proportions between the tire and the wide rim is what makes it better. If they make the tires bigger, then you'll have to chase the bigger tires with wider rims. Also, tire technology has not allowed the tire makers to make wider tires any lighter, and it doesn't make any sense to make the wheel and tire combo any heavier than it is. If you need any bigger than a 40mm wide external rim and a 2.5" tire, then you might as well get a fat bike.


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## cycloxer13 (Oct 27, 2014)

A 2.5 on a wide rim with a more vertical sidewall, I buy it. Okay maybe I exaggerated a bit with 3, but maybe not so much for DH use.


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## Mountain Cycle Shawn (Jan 19, 2004)

cycloxer13 said:


> A 2.5 on a wide rim with a more vertical sidewall, I buy it. Okay maybe I exaggerated a bit with 3, but maybe not so much for DH use.


Yes, less is best here. Even 2.1" tires work very well with wide rims.


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## manitou2200 (Apr 28, 2006)

meltingfeather said:


> Stop digging yourself into a hole and spend 5 minutes reading the links provided.
> you're wrong.
> it's been beat to death here on mtbr.
> simple.


I've read the Schwalbe article, I am a pretty big fan of their products and I have more of their tires than I probably should. Our difference of opinion was in the terms rough terrain vs. more smooth terrain. I was making the rolling resistance comment based on smooth terrain and never refered to rough terrain. This higher pressure bias applies to all tires on smoooth(er) terrain, mtb, road etc. Looking back at your comment I replied to, you did state rough terrain so maybe my reading comprehension was sub par here. I partially blame it on my phones small screen and the fact that I was traveling for work. LOL!



Haymarket said:


> You really should read up on it...counter intuitive and different than resistance on smooth surfaces, but to argue something that has been widely disproven makes yourself look a little silly. Do a search or read the links. Effective rolling resistance is lower at lower pressures on rough terrain. Period.


Agreed and I am a disciple of this belief. I have been running tubeless mtb tires for over 8 years and also the lowest pressures that I can run without rim strikes.



pharmaboy said:


> Im not sure the "period" is really necessary . While it seems to be the case, there hasn't been a re run of the study to reproduce the results, and it wasn't the best quality study ever. Given there is so little info , we go with what we have, but it's a long way from a fact.


I agree with you here! The period was and is not necessary. You have to evaluate your tire and inflation level based on the majority of the terrain you're riding. There is no one does it all!



Mountain Cycle Shawn said:


> The "period" was really necessary!!


No it's not! Period!


J.B. Weld said:


> It doesn't matter how good your reading comprehension is if you're reading the wrong information.


I've not read the wrong info at all. I did miss the rough terrain comment so yep my reading comprehension was well....



Flyin_W said:


> manitou, Regardless of the Schwalbe study that (you haven't read) insists lower pressure / bigger volume are faster in rough terrain.
> Watch any XC race to see who flats. Usually it's not the big guy with the 2.3 / 2.4 tire, more often it's the light weight pushing a 2.0 /2.1 tire.
> Simple fact is very, very few people who flat ever win a race. And if just riding rough terrain who the heck wants to repair a flat?
> Once you try a big volume tubeless tire, you'll (stop arguing) and not go back.


So I own wheels with internal rim widths from 21mm through 39mm and have for more that 7 years. I have tires up to 3" wide and I don't currently run any mtb tires narrower that 2.25. I think I was a bit ahead of the wide rim big high volume tires. The only flat I've had in the last 4 years was on my 30 mm IW rim when I let my air pressure drop to around 15 psi when the temps dropped last November and I did not check the pressure before a ride. Opps!


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> I think I was a bit ahead of the wide rim big high volume tires.


OMG, so now you want us to believe you're some kind of visionary or renaissance man. Boy, where ever you're from, the rivers run deep, wide and fast with BS!


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> OMG, so now you want us to believe you're some kind of visionary or renaissance man. Boy, where ever you're from, the rivers run deep, wide and fast with BS!


Give it a ****ing rest dude! You have a grating personality that adds nothing to any thread on this forum.

I never claimed to be a visionary so don't be butt hurt by my comments! Fricking internet troll boy! Do you ride or just live on this forum?


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> I think I was a bit ahead of the wide rim big high volume tires.





manitou2200 said:


> Give it a ****ing rest dude! You have a grating personality that adds nothing to any thread on this forum.
> 
> I never claimed to be a visionary so don't be butt hurt by my comments! Fricking internet troll boy! Do you ride or just live on this forum?


Haha, I'm ROFLMFAO! Sure looks like you did. It sounds like you're the one who is "butt hurt".


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## oldranger (Apr 14, 2011)

Would you (Shawn) and you MF(er) stop talking about "butt hurt" on my thread. Start your own on that topic since you seem to know a bit about it. I am seriously disappointed this Forum allows you guys to behave like you do. 

By the way - Mr. Moderator, can you have the 'Ignore List' feature enhanced so it also blocks those Users content from my email updates. I really wish it worked that way.

Going off-topic since it seems to be the thing to do here


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## Mountain Cycle Shawn (Jan 19, 2004)

^ Are you butt chapped?


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## oldranger (Apr 14, 2011)

Mountain Cycle Shawn said:


> ^ Are you butt chapped?


Well, now that you mention it...I think so. Based on recommendations in this thread I've been riding with my seat height jacked up for proper pedaling position. That has caused some chafing among other problems. I suppose you will recommend a WIDER chamois in my Lycra shorts. A wider chamois must be way better for DH riding with a jacked up seat-post


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## Yody (Jan 21, 2008)

nerd fight


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> Well, now that you mention it...I think so. Based on recommendations in this thread I've been riding with my seat height jacked up for proper pedaling position. That has caused some chafing among other problems. I suppose you will recommend a WIDER chamois in my Lycra shorts. A wider chamois must be way better for DH riding with a jacked up seat-post


Haha, naw just quit wearing panties, lower your seat a little and you'll be fine.


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## aerius (Nov 20, 2010)

aerius said:


> Fat bikes, clearly, are the future of all racing disciplines!





cycloxer13 said:


> No, but if you spend some time riding one, you may be enlightened by what you can do with wide tires and wide rims.


That was sarcasm actually, but there is a point to it. The claim of the Schwalbe study is that wider tires and low pressure is faster, but they only took it to a moderately sized tire so we don't know if/when that relationship breaks down. Anyone who's ridden a fat bike at 5psi on normal terrain (ie. not snow or sand) can tell you that it's slower than a bike with regular tires, which means that somewhere between 2.2" and 4" the wider=faster correlation breaks down and goes backwards.

I suspect the same is true of wide rims at the current time, a 21mm rim is no doubt better than the 17mm ones I once rode, and 25mm is better than 21mm. But this does not necessarily mean that 35mm or 40mm is better than 25mm, it's entirely possible that wider=better for rims also has a point where it falls apart and is no longer true. We just don't know where that point is or if it exists because no one to my knowledge has systematically tested for it yet.


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## TigWorld (Feb 8, 2010)

Couldn't agree more with Aerius' post. After hundreds of posts, there' still no non-subjective info to be had on rim width. It's been over a year since I posted the following and we're seemingly still no closer to an answer:



TigWorld said:


> ...So why isn't everyone running fatbike rims at 50mm, 70mm or 90mm wide if wider is always better? There must be some point at which "wide" becomes too-wide...


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## Mountain Cycle Shawn (Jan 19, 2004)

^ Some peoples logic just amazes me. As with anything in life, there is a point of diminishing returns. Just because a couple aspirin takes away a minor headache, doesn't mean that you would take a hole bottle for a migraine. Same with wide rims. There's a point at which going wider, isn't going to be better. I haven't heard anyone who has spent a lot of time on 40mm wide rims say anything bad about them. My guess is there is no need to go any wider, unless the terrain you're riding on requires a fat bike.


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## spikebike (Apr 26, 2007)

After reading 28 pages I figured I'd post my impression of the wide rims discussion.

On the good side:
* Wide rims increase the air volume with the same size tire.
* Wide rims support the tire better, allowing better tire support at lower air pressures and less burps.
* Some find the lower tire pressure traction/handling quite compelling.
* Other similar uses like offroad motorcycles have much lower tire to rim ratios, supporting the idea that low tire to rim ratios are a good thing. 
* the tire footprint gets wider and shorter (area unchanged and is directly related to load and air pressure).
* Exactly what is wide seems unclear, but the Derby (external 40mm), Ibis 721 (external 41mm), and Nox Farlow 275 (external 35mm) seem commonly mentioned.

However on the downside:
* Wide rims are heavier (for the same design)
* Lower air pressure and same ride height results in being more vulnerable to pinch flats and rim damage from small rocks and hard edges.
* tire design is sensitive to rim size, pretty much all today popular tires are designed for non-wide rims. 
* Increased air volume means a more linear compression rate, easier to bottom out than a lower volume wheel setup.

Seem like a reasonable summary of the thread?


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## Alias530 (Apr 1, 2013)

Ibis 741 though, not 721


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## eb1888 (Jan 27, 2012)

Many riders will be coming to a carbon Chinese rim as light as 390g-450g from a heavier oem wheelset or skinnier aluminum rim that weighs about the same or more.

From my experience, a 30mm inside rim can allow you to use a lighter faster rolling tire in some terrains and still get a good performance improvement in grip and washout resistance.

For a hardtail the bigger volume adds comfort in the rear and some small bump compliance at the front.


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## brentos (May 19, 2006)

spikebike said:


> After reading 28 pages I figured I'd post my impression of the wide rims discussion.
> 
> On the good side:
> * Wide rims increase the air volume with the same size tire.
> ...


Yep, seems about right. Great summary.


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## cycloxer13 (Oct 27, 2014)

spikebike said:


> After reading 28 pages I figured I'd post my impression of the wide rims discussion...Seem like a reasonable summary of the thread?


Excellent recap.


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## LyNx (Oct 26, 2004)

I'd say that's a pretty reasonable summary of wide rims to me.

What I've come to the conclusion from my little bit of experimenting with WTB i25s and Velocity Dually45s with tyres from 2.25"-3", is that matching the right width rim to the right width & shape tyre is very important. For me, I think rim width should fall within a percentage of the tyres width to be used on them, but need to also take tyre profile_ (squarer or rounder)_ into consideration, but somewhere around 50-60% external measurement should give you a nice shape and lots of sidewall support to help eliminate tyre roll, allowing for lower pressures, which will give you better tyre conformation to the obstacles and hence better grip etc, etc.



spikebike said:


> After reading 28 pages I figured I'd post my impression of the wide rims discussion.
> 
> On the good side:
> * Wide rims increase the air volume with the same size tire.
> ...


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## Mountain Cycle Shawn (Jan 19, 2004)

This tread needs some pictures. 26" x 40mm Derby rims with Hadley hubs, DT Swiss Revolution spokes and Sapim Polyax 14mm nips, so they stick out nice and far when the weather gets cold. I'm waiting for a pair of American Classic valves. Build weight is 1690 grams.


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## spikebike (Apr 26, 2007)

LyNx said:


> I'd say that's a pretty reasonable summary of wide rims to me.
> 
> What I've come to the conclusion from my little bit of experimenting with WTB i25s and Velocity Dually45s with tyres from 2.25"-3", is that matching the right width rim to the right width & shape tyre is very important. For me, I think rim width should fall within a percentage of the tyres width to be used on them, but need to also take tyre profile_ (squarer or rounder)_ into consideration, but somewhere around 50-60% external measurement should give you a nice shape and lots of sidewall support to help eliminate tyre roll, allowing for lower pressures, which will give you better tyre conformation to the obstacles and hence better grip etc, etc.


Sounds reasonable, just like the ibis page says.

> If you look at nearly all other vehicles, the ratio of outer tire width to inner rim width is anywhere from 1.2:1 to 1.5:1.

> Here are a few examples:
> Road bike 1.2: 1
> Motorcycle 1.3-1.5:1
> Car 1.3:1
> Mountain bike 3:1

It's pretty clear what the outlier is.


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## Mr.P (Feb 8, 2005)

spikebike said:


> After reading 28 pages I figured I'd post my impression of the wide rims discussion...


Nice distilling spikebike, a great post.

It looks like the only real questions left are how much more grip and survivability we attain from a wider rim and if it is worth the thousand+ dollars to get it.



spikebike said:


> * Increased air volume means a more linear compression rate, easier to bottom out than a lower volume wheel setup.


I'll just call this one out as unlikely for 2 reasons.

A large ramp up or progression of the spring curve happens when the air gets compressed into a very small volume relative to it's starting volume. A tire does not reduce that much volume when it hits a rock or lands hard.

In addition, when hitting a large square edged rock, for example, the rock's entry into the tire casing takes volume away from the tire, and increases air pressure within the tire. When the air pressure increases, the tire casing will expand a very small amount in reaction - across the entire casing - actually adding some volume.

P


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## Aglo (Dec 16, 2014)

spikebike said:


> * the tire footprint gets wider and shorter (area unchanged and is directly related to load and air pressure).


this should be changed to


> ** at the same pressure* the tire footprint gets wider and shorter (area unchanged and is directly related to load and air pressure).


it makes clear to understand that is the air pressure and load that change the area of the contact patch, and not the wide of the tire.


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## PretendGentleman (May 24, 2011)

Mr.P said:


> Nice distilling spikebike, a great post.
> 
> A large ramp up or progression of the spring curve happens when the air gets compressed into a very small volume relative to it's starting volume. A tire does not reduce that much volume when it hits a rock or lands hard.
> 
> ...


I too appreciated spikebikes informative post!

Wouldn't the give of the tire contribute to a worse than linear spring rate? We've got pv=nrt. We're changing v, so p should change to compensate, pushing back, but when you reduce the volume by 10% due to a big strike, the pressure would ramp up by 10% except the volume doesn't really go down 10%, since the rest of the tire is expanding, so tire pressure spikes by a smaller percentage, as if there was less air in the tire. I suspect we could put together a stochastic model, gather a bunch of data and estimate coefficients A and B, i.e., P=Bnrtv^A+random error, and we'd find that A is something like -.9 on a wider rim and maybe -.95 on a narrower rim.

The experiment would ask how much force does it take to reduce the volume of a tire such that the rim just bottoms out. This could be conducted over a wide range of starting tire pressures. My version of the math has a lot of simplifications relative to deriving the actual expression for estimating this relationship (e.g., non-linear relationship between force and pressure due to changing contact patch), but a black box/reduced form model like this could suss it out if someone would just gather the data. That chain friction facts guy seems to be game to funding these sorts of experiments 

I'm not a physicist, just a babbling staticstician/economicst, but based on ideal gas laws, I think somethign along these lines is what we would look at to determine a non-linear/progressive/regressive spring rate. The expansion of the rim (as long as volume is rising due to the expansion) contributes (perhaps) to a regressive spring rate, and the bigger the change in volume due to a given strike causing initial tire deformation, the more the rate is regressive.

*I'm keen in particular about advice on the following*:
EDIT: this question pertains to 29+, specifically knard on rabbit hole is what I just destroyed (after 2 years (25 months), ~50 mile per week including 10 days of loaded bikepacking and a broken krampus frame)
since we're in a thread where people are considering this sort of question carefully:
I just destroyed my rabbit hole rim and am always constrained by the need to avoid bottoming out my tire and damaging the tire bead/sidewall junction and the rim too. Everyone I read about in my weight range (225lbs fully loaded) runs no more than 15 psi. I have to run 20 psi rear to reduce rim strikes to ~once per 50-100 miles. Tires still fail to hold tubeless at the bead from damage within 6 months of installation (all this is for rear tires only, but front tires require higher pressure for me than many other folks(~18 psi)). At the 12 psi that many 29+ riders report for rear tires, I can nearly bottom out the front rim preloading for a bunnyhop, which is scary when at speed.

light bike has a 50mm carbon rim for $200 that is vaguely tempting, but I'd probably end up running 22psi out of fear of cracking it on a rim strike. Perhaps I should go with a 35-40mm wide rim to save money at no cost in handling since I run high pressures anyways?


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## pharmaboy (Nov 11, 2005)

Hi, interesting read. I don't know where you are getting your pressures from, but at 20lbs less than you, 22psi in the rear nearly always results in a rim strike for me. I know because I get a rim strike, then check pressure and note it's way down. I run 20psi in the front and 30psi in the rear.

I am xc only dual suspension so often are seated for a 1" high root. Most people in xc in my riding group and around my weight are running low twenties in the front and high twenties in the rear except for one guy who is pretty aggressive who is running 30 front and high thirties rear.

Note - my pressures are off a track pump that agrees with a schwalbe digital pressure guage


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## ColinL (Feb 9, 2012)

PretendGentleman said:


> I just destroyed my rabbit hole rim and am always constrained by the need to avoid bottoming out my tire and damaging the tire bead/sidewall junction and the rim too. Everyone I read about in my weight range (225lbs fully loaded) runs no more than 15 psi. I have to run 20 psi rear to reduce rim strikes to ~once per 50-100 miles. Tires still fail to hold tubeless at the bead from damage within 6 months of installation (all this is for rear tires only, but front tires require higher pressure for me than many other folks(~18 psi)). At the 12 psi that many 29+ riders report for rear tires, I can nearly bottom out the front rim preloading for a bunnyhop, which is scary when at speed.
> 
> light bike has a 50mm carbon rim for $200 that is vaguely tempting, but I'd probably end up running 22psi out of fear of cracking it on a rim strike. Perhaps I should go with a 35-40mm wide rim to save money at no cost in handling since I run high pressures anyways?


"everyone" is either full of crap, rides nothing but sand & snow, or has defective tire pressure gauges.

"everyone" doesn't pay for new wheels: you do. 15 psi is nowhere near enough for anything less than a fatbike.

pharmaboy is correct, and since you just wrecked a rim, you have empirical evidence that you were not running enough air in your tires. I don't understand why you think that 22psi is a lot in a rear tire, at 225 pounds. It isn't a lot, at all.

you're not really giving up anything. just inflate the tires more. you'll get enough traction, and more importantly, you'll destroy fewer wheels.


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## PretendGentleman (May 24, 2011)

I just added a note to clarify this on my previous post. 

This is for my krampus running 3" knards on 50mm external width rabbit hole rims. I've had the rim through many miles and 2 rebuilds (3 different hubs as I destroyed 2 shimanos (Xt and slx) before upgrading to dt 350. For this setup, 15 psi is typical. I do have several dents in my rim from low pressures, but often due to failing tires.

so in summary, I run higher than normal pressures for my format (29+) and am wondering if I would notice any adverse affect if I replace my 50mm wide rim with a 35-40mm rim that will cost a good bit less. I'm leaning towards replacing with the same width, but would downsize if my high pressures are likely to be erasing the benefits of a full 2" rim for 3" tires.


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## oldranger (Apr 14, 2011)

Mountain Cycle Shawn said:


> This tread needs some pictures. 26" x 40mm Derby rims with Hadley hubs


This is too much to handle. MC Shawn...you are building a 26" wheelset.

These pictures are the best ever. Are you kidding me!?! You bashed others (me, the OP) for not embracing the new technology of wide rims...you wrote: "_they can't or don't want to keep spending the money to constantly upgrade their bike with better technology_"...and you put yourself in the "_99% of us that embrace the change_".

Yet you are building up a set of 26" wheels for a trail bike. If anyone is still listening to you for advice on how to find the future of wheel design - they are hopelessly lost.

P.S. Folks: If you are new to DH (Downhill) and trying to get something out of this thread about PSI - please go elsewhere for advice. This thread has been contributed to by folks discussing PSI for light to moderate trail riding demands where pedaling uphill and negotiating trails slowly are in consideration. There may be some good advice in there for that.

P.P.S Folks: I'm sorry for stooping to Mr. Shawn's level of personal attacks, but it appears that is fair game on MTBR. I just want to make sure no one misses the obvious hipocrisy. Visionaries are not out building 26" wheel sets.


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## meltingfeather (May 3, 2007)

oldranger said:


> This is too much to handle. MC Shawn...you are building a 26" wheelset.
> 
> These pictures are the best ever. Are you kidding me!?! You bashed others (me, the OP) for not embracing the new technology of wide rims...you wrote: "_they can't or don't want to keep spending the money to constantly upgrade their bike with better technology_"...and you put yourself in the "_99% of us that embrace the change_".
> 
> ...


This post demonstrates what we suspected all along: you're not an honest seeker looking for dialogue. You're a petty poon tang looking to prove something. GTFO.


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## Yody (Jan 21, 2008)

oldranger said:


> This is too much to handle. MC Shawn...you are building a 26" wheelset.
> 
> These pictures are the best ever. Are you kidding me!?! You bashed others (me, the OP) for not embracing the new technology of wide rims...you wrote: "_they can't or don't want to keep spending the money to constantly upgrade their bike with better technology_"...and you put yourself in the "_99% of us that embrace the change_".
> 
> ...





meltingfeather said:


> This post demonstrates what we suspected all along: you're not an honest seeker looking for dialogue. You're a petty poon tang looking to prove something. GTFO.


Actually I liked his post. Spot on oldranger


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## pharmaboy (Nov 11, 2005)

PretendGentleman said:


> I just added a note to clarify this on my previous post.
> 
> This is for my krampus running 3" knards on 50mm external width rabbit hole rims. I've had the rim through many miles and 2 rebuilds (3 different hubs as I destroyed 2 shimanos (Xt and slx) before upgrading to dt 350. For this setup, 15 psi is typical. I do have several dents in my rim from low pressures, but often due to failing tires.
> 
> so in summary, I run higher than normal pressures for my format (29+) and am wondering if I would notice any adverse affect if I replace my 50mm wide rim with a 35-40mm rim that will cost a good bit less. I'm leaning towards replacing with the same width, but would downsize if my high pressures are likely to be erasing the benefits of a full 2" rim for 3" tires.


Oh, that'd change things some. I'd go fatbikes forum for that question - nextie s are the business for fatties, not sure about the half fatty though


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> This is too much to handle. MC Shawn...you are building a 26" wheelset.
> 
> These pictures are the best ever. Are you kidding me!?! You bashed others (me, the OP) for not embracing the new technology of wide rims...you wrote: "_they can't or don't want to keep spending the money to constantly upgrade their bike with better technology_"...and you put yourself in the "_99% of us that embrace the change_".
> 
> ...


I have no problem with upgrading and there are no lack of funds for me to upgrade. I like the SC Nickel LT that I have and I'll upgrade to a 27.5 when this bike is thrashed. I don't upgrade just for the sake of it.


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## meltingfeather (May 3, 2007)

Yody said:


> Actually I liked his post. Spot on oldranger


Good for you. Funny that you'd feel motivated to post support for such a douchey personal attack post. Birds of a feather I guess... I guess you ride the same wheel size oldranger does, so your opinion counts or something? Hard to follow the "logic." :thumbsup:


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## Mountain Cycle Shawn (Jan 19, 2004)

The difference here is, I'm not saying that other wheel sizes are bad or they don't work well. Each has its place. I'm just not ready for a change in wheel size yet. I also haven't switched to a one ring up front. For where I ride it doesn't make sense yet.


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## Mountain Cycle Shawn (Jan 19, 2004)

meltingfeather said:


> This post demonstrates what we suspected all along: you're not an honest seeker looking for dialogue. You're a petty poon tang looking to prove something. GTFO.





meltingfeather said:


> Good for you. Funny that you'd feel motivated to post support for such a douchey personal attack post. Birds of a feather I guess... I guess you ride the same wheel size oldranger does, so you opinion counts or something? Hard to follow the "logic." :thumbsup:


Thanks man for the support!


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## oldranger (Apr 14, 2011)

Melting Feather: im gonna call you out too. I started this thread and have had to tolerate your lack of discipline and straying off topic for a year now. It has really eroded the quality of this discussion.

Show us a pic of you riding a proper DH bike on a race trail, or you GTFO. You have been contributing to this thread as though you are an expert and are knowledgeable on the subject, yet all indications are that you should have started your own thread on wide rims for the kind of riding you do...not DH.

On the 'wider is better' side of the argument - I have seen some interesting pics from the Fontana Series. DT Swiss is making a 27.5 rim with a 'Gravity' label that is wider than the Ex471 that we saw the Specialized guys running last year. What are you guys seeing out there?


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## oldranger (Apr 14, 2011)

Don't believe the hype: Melting Feather and MC Shawn do not appear to own downhill race bikes. They also have not spoken in detail of their personal downhill-specific experience. They just don't like the way I started this thread.


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> Don't believe the hype: Melting Feather and MC Shawn do not appear to own downhill race bikes. They also have not spoken in detail of their personal downhill-specific experience. They just don't like the way I started this thread.


Says the one who has no experience on truly WIDE rims. At least I have experience with them at DH speeds.


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## pharmaboy (Nov 11, 2005)

Only in the truly unscientific world does experience trump understanding.

It's this line of argument that goes, I don't understand how the eye came to being, no one has been able to explain it to me so I understand, therefore God did it, and evolution is a steaming pile.....

Seriously, personal experience is not a level of evaluation that should hold any currency at all - it's more likely to delude than inform. That goes for both sides of the argument here. Physics and engineering can and does explain what's going on, and can predict the upsides and the downsides. Those engineers employed by multinational bike part companies hopefully get to run the show, though mtbr seems to indicate that whatever the marketing dept dreams up can also get a run for a few years untill the next big thing


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## aerius (Nov 20, 2010)

Been keeping an eye on this one since the Ibis Enduro team announced that they're going to be using the 741 wide carbon wheels.
Ibis Cycles 2015 Enduro Race Team | News | Info

Seems like ACC isn't in on it yet since according to the March 1st post on her page she's already racing, and those are Crossmax wheels on her bike.
https://www.facebook.com/acchausson?fref=ts

Sponsorship related? Possibly. Or maybe wide rims aren't necessarily faster.


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## OriginalDonk (Jul 8, 2009)

I believe ACC's primary sponsor is Mavic (wheels, shoes, jerseys, and (sometimes) tires). It's the first brand listed on her site and has been a long time supporter. Ibis is next followed by Formula (maybe she'll run a Formula fork in addition to brakes?).

I remember reading on a forum after the Mojo HD3 launch that ACC was loving the traction that the wide rim provided on the front but felt that wide rear lacked the poppy playfulness that suits her riding style and what she wants from her equipment. I believe somebody mentioned she'd run a wide front and narrow rear if she could but that wouldn't pay the bills as well as rollin' on Mavic. She also seems to be doing extremely well on what she does ride.

Sounds like another person with different views based on their skillset, how they ride, and what they ride.


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## highdelll (Oct 3, 2008)

Yody said:


> Actually I liked his post.


I think I did too - pretty funny :thumbsup:


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> Don't believe the hype: Melting Feather and MC Shawn do not appear to own downhill race bikes. They also have not spoken in detail of their personal downhill-specific experience. They just don't like the way I started this thread.


You didn't post this in the DH section. This section is about wheels and tires and this thread evolved to different types of bikes and riding styles. And at times you went with it. ****, you even took the discussion to BMX bikes. And, now you're all pissed off because the discussion has moved away from DH.


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## Mr.P (Feb 8, 2005)

oldranger said:


> P.S. Folks: If you are new to DH (Downhill) and trying to get something out of this thread about PSI - please go elsewhere for advice. This thread has been contributed to by folks discussing PSI for light to moderate trail riding demands where pedaling uphill and negotiating trails slowly are in consideration. There may be some good advice in there for that.


Keep in mind, your original post asked about pro rider psi, and how they are going so fast on narrower rims. But all of us ride at "light to moderate trail riding" speeds compared to the pros, including yourself. So none of us can relate. We also don't have our income riding on not-flatting like the pros do. It's most likely we never come close to pushing a tire as hard as a top level pro on the world cup during a race run. None of us have anything relevant to say there.

What you do have from this thread is a sliding scale with similar theories applying. Can a rider run less psi on a wider rim than a narrower rim with the same tire/trail/riding technique? XC = yes. DH = yes.

No matter what, it is your duty as a mountain biker who wants the most out of their ride, is to run the lowest tire pressure possible for your own gear/terrain/riding style.

Do I wish I could run lower than 28 psi on the rear of my SS hardtail? Bone jaringly, hell yes. But the sound and feeling is too ball shrivelling when I land a whipped huck sideways and fold the tire over when I run below 28 psi. That is on a Flow rim. So on a 30+ ID rim with a 2.2 tire, can I run a cushy 24 psi and not fold the tire over when I am getting irie? Now we are talking!

Be thankful the thread has gone on as long as it has looking for answers. I found some here, and am thankful.

Oh, and I'll make a crystal ball prediction for this year's WC DH races: There will be some teams running wide rims.

P


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## meltingfeather (May 3, 2007)

oldranger said:


> Melting Feather: im gonna call you out too.


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## PretendGentleman (May 24, 2011)

Please resist the temptation to contribute to the trolling by defending yourself/counter-attacking. It's just not worth it, for the health of your own soul. We've all done it and probably will again, so I'm here to support your efforts to stop handing out food to unwanted trolls...

Anybody care to update/summarize? I've been reading through multiple many-page threads as I try to talk myself out of buying carbon rims for my rim busting riding style, so I'm a little unsure what I've read in which thread.

Is the take away from this thread as follows?: wide rims don't do much for you if you are an aggressive rider that must run high pressures to avoid serious rim strikes/damage. When you replace your wheels, go ahead and get wide rims, but don't bother upgrading just for improved performance from wide rims since you won't notice the stability benefits at higher than average psi.

I'd like to hear the results of analysis done by physicists and engineers, but nobody is likely to pay for that and then post the results for free. We also don't know if companies are riding trends that their engineers don't like, but marketing does like. Maybe wide rims haven't showed up on pro's bikes because companies think there is more profit in delaying their use. We simply do not know. I would say the best way to understand the industry is to assume that Bike companies are profit maximizers. A bike company's goal in general is not to further mountain biking as a whole except to the extent that doing so maximizes their profits. This is why we have to guess about these complex issues and we lack a debate between trained engineers with data to backup their theories. This stuff is complex, and smart engineers would likely have disagreements.

I run high psi's on my krampus and on all bikes have always run high pressures (45psi for 2.25" tires, 20 psi for 3"tires) because when I ride cross country I come down hard on my back wheel. I also run high front pressures because bunny hop preloading and bump-jumping big logs on a rigid bike is roughly equivalent to a 2' drop in terms of tire compression. In the fatbike forum, nobody knows about 3" tires, but everyone who isn't fat says to post my question there. ultimately I'll post in both spots until there's a plus-sized forum for us 29+, 27.5+ and 26+ converts. I am tempted by the jungle fox 50mm rim, but am mostly ok that I might kill it in 6 months, but am not ok that I might kill it on a huge ride in the mountains that will end my day of riding and require a long hike to get to a road.


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## forgiven_nick (Nov 7, 2006)

I agree with just about everything you wrote right there PretendGentleman. I am in a similar place to you as a 29+ convert and also would love running carbon rims aside from the desire for durability during the long days in the saddle out in the backcountry. My philosophy is to run slightly narrower rims (35mm to 45mm) for 3 in tires and higher pressures on rides where larger impacts at higher rates of speed are probable, lowering the pressure when desired for a particular segment of trail warrants it or if a slower pace and/or compliance is desired. My preference, after running wider rims and tires is to adjust air pressure on the trail because it changes the ride significantly when you have plenty of volume to work with. Some of my DH friends have done this for years on their 26x2.5 bikes when pedaling up a long road to get to the trail, starting with a higher pressure for the long climb, then letting out a significant amount of air once they reach the trailhead. Being an xc rider primarily, I always kept my tires at pressures that would be good for all around riding, the same pressure for the entire ride since I enjoy covering as much ground as possible on each ride and dislike stopping for adjustments. I will stick to the pressure I initially start the ride with for most rides under 2 hours, but it's nice to have the option to really dial in the pressure for the intended application.


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## jonshonda (Apr 21, 2011)

This thread is trying to be salvaged by a few good peeps....well done!

We should eliminate DH from this conversation, as it might be safe to say the tire technology isn't in line with a wide rim yet.

It would be safe to assume that there are a lot of people who do enjoy/benifit from wider rims/tires. Take a look at all the happy Krampus owners out there. Yes, I understand the tires are larger in diameter, but they are also much larger in volume. I don't know of too many people in the mutiple Krampus threads that are having chronic issues with rim strikes and pinch flats. 

So if you can base your opinion on a select few users who might not be the the best at finding solutions to rim strikes or pinch flats, then you are basing your opinions on poor examples. Also take a look at all the happy P35/Blunt owners out there. Yes, some of them are getting rim strikes, but could you not conclude that at pressure required to eliminate rims strikes, the feel and performance of the tire was better?

I am going to have to conclude that the right wheel/tire setup correctly (psi) is really going to be a lot of fun to ride. Honestly, how could you not want 35-40mm rims with tires like Maxxis Ikons (2.35) or Ardents (2.4)? Should we ever expect a 225lb rider to be able to sit on the saddle through a rock garden at 15psi on anything other than a 4" tire, and not expect rim strikes? 

I am not trying to be rude, but the first time I would experience a rim strike on a common trail feature, I would up the psi until it no longer happened....that is just common sense. Once I reached that pressure, and determined I gain no additional performance from the setup, I would then conclude that there was no benifit. 

You need to weed out the bs and remember to not base opinions on a select few. If Henry Ford did that, people would still be riding horses.


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## oldranger (Apr 14, 2011)

Mr.P said:


> No matter what, it is your duty as a mountain biker who wants the most out of their ride, is to run the lowest tire pressure possible for your own gear/terrain/riding style...
> ...Be thankful the thread has gone on as long as it has looking for answers. I found some here, and am thankful.


Good advice; I am in search of the lowest possible pressure myself. I am also thankful for much of the contribution to this thread.

On PSI: I have learned through trial and error that finding the right PSI is challenging. Sometimes, I've had a different ride at top of a DH run because it is 5,000 feet higher than the base where I set my psi. Sometimes on trail rides I take the descents a bit more carefully because I'm on the low range of what can support me to get up some of the climbs. I've had my fair share of flats, but have found pressures that get me home or to the finish line 90% of the time without stopping for a flat.

DH is part of this thread, even if just by those that read only. Note for DHers: I think it is really tough to take specific psi recommendations from internet sources. There are too many variables. Also consider:

1) Choosing the optimal PSI for a 2 hour trail ride has got to be different than choosing PSI for a 4 minute DH race. The tires are different, and the requirements during a 2 hr trail ride with 'technical' climbing (and some very low speeds) place a far different set of demands than a typical DH race run does.

2) On some DH tracks the lowest pressure might be dictated by a significant rock garden while on other tracks it might be dictated by pressure you need to keep the tires from folding over in high speed turns.

3) On some DH tracks the highest pressure might be dictated by off camber, wet rooty sections that have to be done right or a crash will result. This might slow you down in the rocks and dry berms at the bottom of the track.

In general: be careful about applying lessons learned from your trail riding to your DH bike for anything other than a starting point. For DH - you will be making decisions based on a more narrow set of requirements and might even run a different psi throughout the day if rain is in the equation. Having a good pressure gauge is one of the best tools in your toolbox.


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## Mr.P (Feb 8, 2005)

oldranger said:


> On PSI: I have learned through trial and error that finding the right PSI is challenging. ...In general: be careful about applying lessons learned from your trail riding to your DH bike for anything other than a starting point. ...


Quoted for truth!!!

PSI is totally subjective to the individual rider - even within a segment of riding, like DH.

You can tell the PSI nerds - they are the ones at the trail head pumping and checking PSI right before the ride. And they will all have to bring their own pump that they are calibrated to. And they will hit a specific PSI number or it will mess with their head for the rest of the ride. Ha! (How do I know all that, ha ha)

I have found that I feel squirmy tires in turns 2-5 psi before I am at pinchflat danger on 21-23mm ID rims. I run big tough tires and like to smash turns. My local rides also include sharp embedded shale rock in high speed downhill sections.

P


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## meltingfeather (May 3, 2007)

Mr.P said:


> PSI is totally subjective to the individual rider - even within a segment of riding, like DH.


Wait, so we're not supposed to set PSI to what Minnaar uses?

I'll go back to the beginning of this thread and point out that, like PSI, rim width is an individual choice best determined by riding bikes. What works or doesn't for anyone else is hardly relevant.
Revolutionary, I know.
If you like wide rims and they work (or even if they don't), why the need to broadcast your opinion as some sort of rule others should heed?


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## Mr.P (Feb 8, 2005)

meltingfeather said:


> Wait, so we're not supposed to set PSI to what Minaar uses?


I use Peaty's PSI, cuz I'm old school.

P


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## Mountain Cycle Shawn (Jan 19, 2004)

It looks like the first wide rim tires are on the truck. Disclaimer: This link takes you to another bike site. Please return to MTBR.com ASAP for all your biking needs.
Introduction to Project 27Plus - WTB Scraper rims and Panaracer Fat B Nimble tires


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## spikebike (Apr 26, 2007)

Mr.P said:


> Nice distilling spikebike, a great post.
> 
> It looks like the only real questions left are how much more grip and survivability we attain from a wider rim and if it is worth the thousand+ dollars to get it.


Did you mean to replace a current wheelset? Or comparing a high quality normal wheelset to a high quality wide wheelset? If you are shopping for a new wheel set the premium for a ibis 741 or nox farlow doesn't seem bad when compared to similar quality wheelsets with 20-30mm wide rim wheelsets.



Mr.P said:


> I'll just call this one out as unlikely for 2 reasons.
> 
> A large ramp up or progression of the spring curve happens when the air gets compressed into a very small volume relative to it's starting volume. A tire does not reduce that much volume when it hits a rock or lands hard.


My main point is unlike much of the hype, the wide rims are MORE vulnerable to snake bikes than thinner rims. Even if the effect is VERY small, it's worse not better. This is made much worse if you run lower pressure which is frequently mentioned in the advantages of wide rims. So sure you get better control of the tire at lower pressures, but you are risking snake bikes and/or rim damage in the process.


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## PretendGentleman (May 24, 2011)

spikebike said:


> My main point is unlike much of the hype, the wide rims are MORE vulnerable to snake bikes than thinner rims. Even if the effect is VERY small, it's worse not better. This is made much worse if you run lower pressure which is frequently mentioned in the advantages of wide rims. So sure you get better control of the tire at lower pressures, but you are risking snake bikes and/or rim damage in the process.


I agree with you that the smaller starting volume leads to a more progressive spring rate (but I might be using physics terms incorrectly), but I'm curious if your explanation is the same as mine. I'm not sure if folks are referencing a breakdown in ideal gas laws or just an artifact of the behavior of variables that respond to each other in percentages (in a perfect system, based on P=(nRT)V^-1, if V goes down 2%, P goes up approximately 2%~1-1/(1-.02)). This approximation breaks down for big changes, so a 20% reduction in volume causes about a 25% increase in pressure, .25%=1-1/(1-.2). So one argument, that I would have to think too hard about as someone who does not do much 3d geometry or integrals is the question of whether a wider rim vs a narrow rim experiences a larger percentage reduction in volume when experiencing a load that is just enough to cause a rim strike. I think i know how to prove the answer, but intuitively, i suspect the narrower rimmed wheel experiences a larger percentage reduction in air volume due to a rim strike, thus the spring rate is relatively more progressive than for the wide rim system.

I am now leaning towards a 40mm rim for my krampus rear wheel. I like that I would buy a bit more flexibility on chainline and running a granny gear for huge climbs. Every mm really does count with this setup.


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## Mr.P (Feb 8, 2005)

spikebike said:


> My main point is unlike much of the hype, the wide rims are MORE vulnerable to snake bikes than thinner rims. Even if the effect is VERY small, it's worse not better. This is made much worse if you run lower pressure which is frequently mentioned in the advantages of wide rims. So sure you get better control of the tire at lower pressures, but you are risking snake bikes and/or rim damage in the process.


I posted this a few posts above:


> I have found that I feel squirmy tires in turns 2-5 psi before I am at pinchflat danger on 21-23mm ID rims. I run big tough tires and like to smash turns. My local rides also include sharp embedded shale rock in high speed downhill sections.


So if I can drop a few PSI, gain more grip, and not have a squirming tire all while still not striking there rim - that is a huge win. I'm not talking stupid low pressures, just 2-5 less PSI than I run now.

Regardless, this is tubeless we are talking about, bottoming out on the rim is not that big of deal. I used to bottom out once per race without issue when I was racing XC - that was with a 400g, 2.1, semi-slicks on Flows at 22psi (I'm 180#).

That 2.1 on 23mm inside width Flows set-up were like 2.35 on 30mm inside width rims in regards to tire size to rim inside width ratio. So I already have some experience with this. (That is 2.3:1 and 2:1 tire/rim size respectively, so not exactly, but close enough to realize some benefits.)

P


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## eb1888 (Jan 27, 2012)

There's more.
The added volume gives you more ride compliance front and rear. This makes a hard tail more distance capable. And one with some vertical compliance a short travel fs substitute.
The sidewall support reduces greatly abrupt washouts, like when you try to recover from a mistake.


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## spikebike (Apr 26, 2007)

PretendGentleman said:


> I agree with you that the smaller starting volume leads to a more progressive spring rate (but I might be using physics terms incorrectly), but I'm curious if your explanation is the same as mine. I'm not sure if folks are referencing a breakdown in ideal gas laws or just an artifact of the behavior of variables that respond to each other in percentages (in a perfect system, based on P=(nRT)V^-1, if V goes down 2%, P goes up approximately 2%~1-1/(1-.02)). This approximation breaks down for big changes, so a 20% reduction in volume causes about a 25% increase in pressure, .25%=1-1/(1-.2). So one argument, that I would have to think too hard about as someone who does not do much 3d geometry or integrals is the question of whether a wider rim vs a narrow rim experiences a larger percentage reduction in volume when experiencing a load that is just enough to cause a rim strike. I think i know how to prove the answer, but intuitively, i suspect the narrower rimmed wheel experiences a larger percentage reduction in air volume due to a rim strike, thus the spring rate is relatively more progressive than for the wide rim system.


Yes, ￼PV=nRT applies. Less volume means the pressure goes up more quickly for a given compression. So running over a softball with a 30 PSI tire is going to cause more of a pressure spike with a small volume tire than a large.

Well keep in mind:
* the part of a tire that compresses during a hit is a very small percentage of the entire tire. Unlike say a rear shock where 100% of the piston area compresses.
* So sure the larger volume tire+rim is more linear, but who cares. Likely way smaller than the error in your average bike pump.



PretendGentleman said:


> I am now leaning towards a 40mm rim for my krampus rear wheel. I like that I would buy a bit more flexibility on chainline and running a granny gear for huge climbs. Every mm really does count with this setup.


I don't see what a wide rim has to do with chainline or granny gears. Wide rims have minimal effect on wheel radius, chain line, or tire width.


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## PretendGentleman (May 24, 2011)

rim width definitely has an affect on chain line compatibility with wide tires. I ride a krampus and I deal with this regularly as I switch between 1x, 2x, and 3x chainrings for dramatically different terrains/goals.... Mountains vs. plains/party pace vs race pace.

1mm makes a *meaningful *difference; you are not wrong to say the effect is minimal, but in this case minimal is significant. now you know what rim width has to do with chainline and granny gears :thumbsup:. have you seen the posts all over mtbr of people measuring their tires on different rims with calipers and observing differences and then talking about those differences as if they cared about them....

And regarding the pv=nrt stuff, I do not understand the comparison with a bike pump, but can imagine you might be saying the error in a bike pump's gauge is bigger than the error you get if you assume changing rim width has no affect on handling/pinching. I would say that spring rates are regressive (exponential coefficient on P or V is less than 1 in absolute value) for wide or narrow rims due to the expansion of the tire.

I'm not sure how "spring rate" is defined, but pv=nrt is a log linear system, so it might be useful to recognize that P does not respond linearly to V but rather the log of P responds linearly (or nearly so) to changes in the log of V. A physicist could clear this up, I suspect that spring rates are defined such that pv=nrt being log linear means the spring rate is linear (approximately, which of course is the approximation we're implying in this thread should not be made).

Regarding your other points, small differences are exactly why this thread exists. They do matter, otherwise we wouldn't have dozens and dozens of replies. If the percentage change in volume is small, then we can approximate the response of pressure to volume in constant elasticity terms (1% drop in V causes ~<1% rise in P). The different starting points in the 2 systems and the different changes in volumes for a rim strike means different changes in V. This doesn't mean that a small percentage change in volume makes the discussion of the merits of wide rims in this thread moot. A big percentage change would lead to a larger divergence between the handling characteristics of wide and narrow rims. But we don't need anything to be *big* to have a useful convesation about it.

Alltogether rim width has a small effect on pinch flats and handling, and we are internet nerds who spend hours talking about small effects, so when we have a chance to leave our offices to ride our bikes, we are more likely to have a successful experience.


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## libertybike (Mar 12, 2015)

*Ibis released 41mm rims last year*

Great thread and I went through some of this thread but did anyone notice IBIS's new stance on wider rims?

"There are exceptions. Downhillers generally use wider rims as they see the benefits of increased control and far superior traction. Wide aluminum rims are heavy though, unacceptably heavy if you ever need to pedal up a hill or accelerate.

We're not the first people to discover the wide rim advantages. The early mountain bikers as mentioned above had it right. Back in 2011, Richard Cunningham, the Pinkbike.com tech guru wrote an article called "Wider Rims Are Better" in his Pinkbike Tech Tuesday Series. RC had it right, and we encourage you to read the article. In 2012 Richard wrote about the Syntace W35 MX 35mm wide aluminum rims, once again beating the wide rim drum.

In 2013 the first wide carbon fiber rims came out, called Derby Rims. Derby is our good friend and in fact Ibis liked his idea so much we funded half the original tooling expense of these rims. Having access to the Derby Rims proved invaluable in testing for our own concepts and designs. Derby's rims are made in a different factory than ours, as we will be needing a much larger quantity than his source can provide.

For now, we will only be selling complete wheels, so if you're looking for rims only, we heartily endorse the product that Derby is selling. If you can get them that is, Derby Rims have been regularly selling out each production run."

IBIS is now primarily selling wheelsets that have 41mm wide rims. These new rims are coming stock on many of the bikes they sell including the new Mojo HD3. You can check it out on their website. 
I just purchased a set of these rims and will be trying them out probably today if everything goes as planned. Every review I have read so far on the wide rims has been positive many saying it is a game changer using carbon rims has increased the possibility of widening the rims without vastly increasing the weight.

Also wanted to mention I ride Downhill and Enduro singletrack. I haven't tested the new wheels out but I will report back once I have and take some pictures of my set up. I have been doing a lot of research on this and would not have purchased the new wheels if the evidence wasn't there to suggest this may be a worthwhile upgrade.


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## sherwin24 (Jul 23, 2010)

So...In an attempt to get to the bottom of this, I asked someone who's advice I usually trust, my wife.

I explained to her that the big discussion always used to be about size, how many inches was best (as in 26" 27.5" 29"). She stopped me cold with a laugh and said it is all personal preference, and that it really doesn't matter at all. Her exact words, " ride what you got and ride it hard".

She made perfect sense of a long heated discussion, but I had to delve deeper. It was posited to her that possibly width makes a difference. My exact words, "Is wider better". 

Her answer is as follows: " Ohhh definitely!"

I asked her " is there times when wider is not better?"

"Well" she says " Not really...but.." she got a little bit sheepish, (why I don't know, but I cant think about that and wheels at the same time) "sometimes, not always, well most times, a little less width is good in the rear, than in the front. So in a perfect world, nice and wide up front, a bit less in the back. But like I said, ride what ya got and ride it hard."

This all seems too simple, so I asked "what would be considered too wide?"

She let out a little giggle, and a smile " well if it doesn't fit, then it's a pretty safe bet you bit off more than you can chew."

I hope some of you have the same closure I now have, thanks to my wonderful wife.


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## SS Hack (Jan 20, 2012)

So the wife says go wide? That's as good as anything else we've heard here.


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## Mountain Cycle Shawn (Jan 19, 2004)

sherwin24 said:


> She stopped me cold with a laugh and said it is all personal preference, and that it really doesn't matter at all. Her exact words, " ride what you got and ride it hard".


I have the transcript, and that's not really how it went down. This is what she said: She looked down at your waist area, put her hand on your shoulder and said, "honey, the size really doesn't matter. I'll ride what you got and I'll ride it hard". Dude, she's a keeper!


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## sherwin24 (Jul 23, 2010)

Mountain Cycle Shawn said:


> I have the transcript, and that's not really how it went down. This is what she said: She looked down at your waist area, put her hand on your shoulder and said, "honey, the size really doesn't matter. I'll ride what you got and I'll ride it hard". Dude, she's a keeper!


Well I have no clue what you are talking about haha.

On a side note, my wife just asked me why is wide just now becoming a topic of discussion? I told her it is fairly new and trendy so of course it is getting a lot of airtime.

"Wow, never new I was such a trendsetter, I went wide 14 years ago, can't believe others are just catching on now" was her reply.

I knew she rode bikes when I met her 14 years ago, but I never once thought to see what size rims she was riding.


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## Lelandjt (Feb 22, 2008)

Everyone who wants to run 30+mm carbon rims with low pressure on rocky trails needs to buy the WTB Breakout 2.5".


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## Mountain Cycle Shawn (Jan 19, 2004)

Mountain Cycle Shawn said:


> I have the transcript, and that's not really how it went down. This is what she said: She looked down at your waist area, put her hand on your shoulder and said, "honey, the size really doesn't matter. I'll ride what you got and I'll ride it hard". Dude, she's a keeper!





sherwin24 said:


> Well I have no clue what you are talking about haha.
> 
> On a side note, my wife just asked me why is wide just now becoming a topic of discussion? I told her it is fairly new and trendy so of course it is getting a lot of airtime.
> 
> ...


Show her the above, she'll explaine it to you.

On a side note: These new wide rims are like suspension, disc brakes and pretty much every other major improvement in the mountain bike industry. All the trolls come out if the wood work, declaring how they are horrible and it's just a passing fad. Two years from now everyone will be using them, even the trolls and this BS will all be forgotten.


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## Ridnparadise (Dec 14, 2007)

sherwin24 said:


> Well I have no clue what you are talking about haha.
> 
> On a side note, my wife just asked me why is wide just now becoming a topic of discussion? I told her it is fairly new and trendy so of course it is getting a lot of airtime.
> 
> ...


That's because you were only looking at the rims you gave her! Plus, clearly she has not yet met the limit of her width, but is still looking. i'm sure it will all work out in the end. Just not sure which end.....


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## libertybike (Mar 12, 2015)

*I just ordered the front tire*



Lelandjt said:


> Everyone who wants to run 30+mm carbon rims with low pressure on rocky trails needs to buy the WTB Breakout 2.5".


Have you tried the Breakout 2.5 tires yet? There are two different versions, one for the rear and one for the front. I saw your post and purchased the front tire for my new wheel lol. Going to try it out as I am running 2.4 Ardent/Mking tires right now.

I just gave my wheels their first test ride and they definitely made a difference. I upgraded though from WTB i23 aluminum rims, so I lost weight and have wider rims also, but the overall ride felt faster. I felt I had more traction and more confidence in general when taking hard lines down the trail. I also had more power going up hill or downhill when pedaling. For some reason going off the little jumps on my trail was easier probably because I lost some weight on the rims but the landing felt better as well. It feels like I have just increased the size of my tires but lost weight off my bike at the same time.

Kona Process DL 134 w/ Ibis 741 rims 41mm wide


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## Ipe (Jan 28, 2014)

Gotta say libertybike, thats a sweet looking setup you've got there. I've always liked the new Kona Process and yours looks especially sharp. Custom decals on the rims? The color match is perfect. 

FWIW, I'll be ordering a set of Derby's for my SB66 soon. I get the feeling that in a few years finding a narrow, or non-wide, rim on a new bike is going to be as uncommon as a newly released 26er.


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## sklein (Jan 1, 2005)

Wow...Great post (lots of interaction which is great!)
A lot has been said and argued here, some science and some circumstantial, but the bottom line is this: In the early '90's we rode the Red compound RITCHEY v-max 2.35 on our rigid bikes to get more volume (more cushion) and a better contact patch. We dropped the pressure as much as we dared and carried extra tubes for the snake bites that this set-up caused. I switched to IBIS 741 rims on my 2014 Turner Burner (41mm wide) and can't believe how much faster my riding is. What a difference in how much more FUN the rides are with these wide rims at the lower tire pressures though! Amazing! I will never regret the $ I spent and will never go back!
See you out there y'all!


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## oldranger (Apr 14, 2011)

For all those DHers out there: my first DH ride/race of the 2015 season was last weekend in Sequatchie, TN.

There were no wide carbon rims to be seen. There was a set of previous generation Enves on a carbon V10. The rest of the riders were on aluminum as far as I could see, though I admit I didn't get a peek at the SRAM team bike. The Scott WC DH Team goes for DT Swiss 471 when it is time to go fast. They pick it over the 570 and the Gravity because weight trumps width and they can handle the replacement situation.

So, from World Cup professional athletes to 40+ weekend warriors to 11 year old shredders...to the bada## dude on the trail bike...we were all riding down some of the steepest, gnarliest tracks we have in the east...without WIDENESS.


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## Mountain Cycle Shawn (Jan 19, 2004)

sklein said:


> Wow...Great post (lots of interaction which is great!)
> A lot has been said and argued here, some science and some circumstantial, but the bottom line is this: In the early '90's we rode the Red compound RITCHEY v-max 2.35 on our rigid bikes to get more volume (more cushion) and a better contact patch. We dropped the pressure as much as we dared and carried extra tubes for the snake bites that this set-up caused. I switched to IBIS 741 rims on my 2014 Turner Burner (41mm wide) and can't believe how much faster my riding is. What a difference in how much more FUN the rides are with these wide rims at the lower tire pressures though! Amazing! I will never regret the $ I spent and will never go back!
> See you out there y'all!


100% true words!!


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## JLF1200 (Sep 16, 2009)

...and for those grasping for an explanation of the above post: you can't exactly claim DH racing is "conservative" when the entire pro field went to bigger wheels last season, (with questionable results, I might add, since the times overall didn't seem to come down drastically). I'm specifically thinking of Bryceland, who switched from 26" to 27.5"... while leading the WC standings. Graves making the Worlds podium on his retrofitted trail bike the season prior. The Specialized team racing enduro rigs when the course asked for it. Large portions of the field switching to flat pedals for sloppy off-camber courses. These guys aren't luddites. They make changes to their bikes to win races.

The truth is, gravity racing is a completely different world than what most mountain bikers know. So you slap fatty rims on your bike and suddenly your cornering ability improves by a huge margin-- great. That speaks more about your ability than the rims, because the same effect would not happen for guys who are really fast. 
MUST WATCH: George Brannigan - Loose Laps - Pinkbike


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## Lelandjt (Feb 22, 2008)

libertybike said:


> Have you tried the Breakout 2.5 tires yet?


Nope. I was trying to get my hands on them all last season but a production problem meant there were only a few pairs and Marco got them. He loved them and they worked for him on trails that demanded grip and where rolling speed was critical. He used those tires in every race last year from flow trails to the ProGRT he won. Now that they're finally available I'll be getting a set each of the softs and hards.
The reason I recommend them for low pressure on wide rims is their nearly DH feeling sidewalls and their width.


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## mazspeed (Oct 17, 2004)

oldranger said:


> For all those DHers out there: my first DH ride/race of the 2015 season was last weekend in Sequatchie, TN.
> 
> There were no wide carbon rims to be seen. There was a set of previous generation Enves on a carbon V10. The rest of the riders were on aluminum as far as I could see, though I admit I didn't get a peek at the SRAM team bike. The Scott WC DH Team goes for DT Swiss 471 when it is time to go fast. They pick it over the 570 and the Gravity because weight trumps width and they can handle the replacement situation.
> 
> So, from World Cup professional athletes to 40+ weekend warriors to 11 year old shredders...to the bada## dude on the trail bike...we were all riding down some of the steepest, gnarliest tracks we have in the east...without WIDENESS.


Does your BS ever stop?


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## Tenuous (Apr 5, 2010)

> (in a perfect system, based on P=(nRT)V^-1, if V goes down 2%, P goes up approximately 2%~1-1/(1-.02)). This approximation breaks down for big changes, so a 20% reduction in volume causes about a 25% increase in pressure, .25%=1-1/(1-.2).


So your math is a bit off. As long as the nRT function stays constant (specifically temp), then the P & V move at a 1to1 ratio in opposite directions. May be easier to think of it as P*V=C so what ever you add to pressure has to be subtracted from Volume or vice versa.


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## ColinL (Feb 9, 2012)

JLF1200 said:


> ...and for those grasping for an explanation of the above post: you can't exactly claim DH racing is "conservative" when the entire pro field went to bigger wheels last season, (with questionable results, I might add, since the times overall didn't seem to come down drastically). I'm specifically thinking of Bryceland, who switched from 26" to 27.5"... while leading the WC standings. Graves making the Worlds podium on his retrofitted trail bike the season prior. The Specialized team racing enduro rigs when the course asked for it. Large portions of the field switching to flat pedals for sloppy off-camber courses. These guys aren't luddites. They make changes to their bikes to win races.
> 
> The truth is, gravity racing is a completely different world than what most mountain bikers know. So you slap fatty rims on your bike and suddenly your cornering ability improves by a huge margin-- great. That speaks more about your ability than the rims, because the same effect would not happen for guys who are really fast.
> MUST WATCH: George Brannigan - Loose Laps - Pinkbike


The Motorhead soundtrack in that vid sealed the deal. :thumbsup:


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## slowride454 (Jan 11, 2014)

oldranger said:


> For all those DHers out there: my first DH ride/race of the 2015 season was last weekend in Sequatchie, TN.
> 
> There were no wide carbon rims to be seen. There was a set of previous generation Enves on a carbon V10. The rest of the riders were on aluminum as far as I could see, though I admit I didn't get a peek at the SRAM team bike. The Scott WC DH Team goes for DT Swiss 471 when it is time to go fast. They pick it over the 570 and the Gravity because weight trumps width and they can handle the replacement situation.
> 
> So, from World Cup professional athletes to 40+ weekend warriors to 11 year old shredders...to the bada## dude on the trail bike...we were all riding down some of the steepest, gnarliest tracks we have in the east...without WIDENESS.


If wideness isn't a priority and weight is then why aren't they on 15-17 wide rims? You keep talking about how DH don't want or need wide rims when they were the first to go back to 23-27 wide rims in the first place.


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## Mr.P (Feb 8, 2005)

oldranger said:


> For all those DHers out there: my first DH ride/race of the 2015 season was last weekend in Sequatchie, TN.
> 
> There were no wide carbon rims to be seen. .... So, from World Cup professional athletes to 40+ weekend warriors to 11 year old shredders...to the bada## dude on the trail bike...we were all riding down some of the steepest, gnarliest tracks we have in the east...without WIDENESS.


Sigh... DH rims have always been the widest rims available - for decades, until the last year or two. Why is that? According to you, just to look pretty (no benefit).

And here come the wide/tubeless/carbon DH rims you and others can't wrap your head around:

PIT BITS - Crankworx Rotorua - Prototype Carbon Rim - PIT BITS - Crankworx Rotorua - Mountain Biking Pictures - Vital MTB

P


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## Mountain Cycle Shawn (Jan 19, 2004)

Mr.P said:


> Sigh... DH rims have always been the widest rims available - for decades, until the last year or two. Why is that? According to you, just to look pretty (no benefit).
> 
> And here come the wide/tubeless/carbon DH rims you and others can't wrap your head around:
> 
> ...


It's just a matter of time. In a year or two the trolls on this thread will be saving their money for wide rims.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> It's just a matter of time. In a year or two the trolls on this thread will be saving their money for wide rims.


Don't be a douche. We get that you love your wide rims, ok?


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> Don't be a douche.


Next time you're in So. Cal., PM me. I guarantee you wouldn't have the balls to say that to my face!


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## slowride454 (Jan 11, 2014)

I must be ahead of the times...I switched to skinnier wheels on my trail bike. Velocity P35 to WTB KOM i23.


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## smilinsteve (Jul 21, 2009)

Here is an older, related thread with a little more substantive discussion:

http://forums.mtbr.com/wheels-tires/tire-height-vs-rim-width-756818.html

Here's some data that agrees with above thread that tire height (therefore circumference) changes very little with rim width:

29er Tires on Different Rim Width Comparison

Quote from Craigsj (who has a pretty damn good record of being correct in this forum) in above thread, that pretty much summarizes things about rim width and tire height:



> The irony is that the original purpose of the thread was to show that height is relatively insensitive to rim width which ran contrary to common lore. The claim has been that wider rims support lower pressures and that is, at its most generous, an oversimplification. Tire pressures can't be lowered when rim strikes are a threat. For some people rim strikes are never a threat and those people are, no doubt, connoisseurs of tire performance here.


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## smilinsteve (Jul 21, 2009)

Ladies and Gentleman of the jury, I'm just a Caveman. I fell in some ice and later got thawed out by your scientists. Your world frightens and confuses me. Sometimes the honking horns of your traffic make me want to get out of my BMW and run off into the hills or whatever. Sometimes when I get a message on my fax machine, did little demons get inside and type it? I don't know. My primitive mind can't grasp these concepts.

So, maybe I'm just simple caveman, but I don't see how wide rims allow lower pressures? Volume is greater, but that would just make the spring rate more linear. It's probably a very small effect, but in any case, I don't see the advantage to this extra volume.

So if tire height is about the same (less than 1mm difference), then lower pressures will just increase the chance of rim strikes. The rim does nothing to make this less likely.

So wouldn't it be funny, if people love the extra traction and cornering of their wide rims, only because they are running lower pressures, when those same pressures could also be used on those old fashioned narrow rims? In other words, the rims have nothing to do with it? :lol:

I'm just thinking out loud. Your ways frighten and confuse me. I'm just a simple caveman.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> On a side note: These new wide rims are like suspension, disc brakes and pretty much every other major improvement in the mountain bike industry. All the trolls come out if the wood work, declaring how they are horrible and it's just a passing fad. Two years from now everyone will be using them, even the trolls and this BS will all be forgotten.


I'm glad I have suspension and disc brakes. I don't think 35 mm bar diameters or tapered head tubes, or 11 gears instead of 10, 9 or 8 did a damn thing for me.

Nothing wrong with questioning the latest fad, especially since there have been some bad ideas in the past. Marketing something new, and making the status quo obsolete or outdated, works. It just works. So that's how we get these improvements. Some good, some not so much.

The main thing to remember is your bike will ride as good tomorrow as it does today. A new fad doesn't matter to your bike. Bikes and dogs are good that way.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> Next time you're in So. Cal., PM me. I guarantee you wouldn't have the balls to say that to my face!


Whether I say it to your face or not has no bearing on whether or not you are a douche, Mr. Internet tough guy. :lol:

Since you call everyone who disagrees with you a troll, don't be so sensitive. If you can dish it out, you can take it.


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## Mr.P (Feb 8, 2005)

slowride454 said:


> I must be ahead of the times...I switched to skinnier wheels on my trail bike. Velocity P35 to WTB KOM i23.


Kinky. What are your thoughts?

P


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## PretendGentleman (May 24, 2011)

Tenuous said:


> So your math is a bit off. As long as the nRT function stays constant (specifically temp), then the P & V move at a 1to1 ratio in opposite directions. May be easier to think of it as P*V=C so what ever you add to pressure has to be subtracted from Volume or vice versa.


That's a negatory there, feller. Try your math: a 20% reduction in P would cause a 20% rise in V to compensate. That's (1-0.2)*P and (1+0.2)*V in mathspeak. What happens to that so-called constant of yours, C? 
C=PV=[(1-0.2)*P] * [(1+0.2)*V]=0.8*1.2*P*V=.96*P*V=.96*C!=C

A good way to think about the question of the effect of varying rim width for a particular tire is to consider that there is one particular rim width that will maximize the volume of the tire: the max-volume rim width. A narrower rim will shrink the volume until the beads are touching and the tire can be assumed to be a circle with diameter equal to the length of a stretched-flat cross-section of the tire. As the rim gets wider than the max-volume width, the tire is being sretched to the point of losing volume, causing a reduction in the outer diameter of the tire. When the rim width is equal to the cross-sectional length mentioned above, then the volume will drop to zero. This would explain why people have conflicting ideas about whether wider rims lead to taller, shorter, or same height tires. They are considering variations in rim width that span the max-volume rim width and thus find different effects on tire diameter of a change in rim width.
The max-volume width would have the closest to linear (log-log linear to be precise, due to the nature of PV=nRT) spring rate and all other rim widths would have more progressive spring rates.

This effect as others have pointed out may be small. The tire physically supporting the rider's load is an important consideration aside from air pressure.


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## spikebike (Apr 26, 2007)

Wider tires allow lower pressures.

Imagine a 1" wide tire @ 30 psi vs a 2.4" wide tire @ 30 psi. The 1" wider tire is going to ride much lower and have a very noticeable flat spot. If you tried to ride a 1" tire @ 30 psi on the trail you'd likely snakebike or damage a rim.

So clearly 2.4" at 30 psi is much better than 1".

Similar rules apply when you use a wider rim instead of a wider tire. The same 2.4" tire will have a wider footprint and a higher ride height when used with a wider rim. Sure the footprint will be the same. Lets assume a 200 pound weight (bike + rider) / 30 psi = 6.66" square footprint.

So with a narrow rim + 2.4 " tire @ 30 psi will have exactly the same size footprint as a wide rim + 2.4" tire @ 30 psi. But the wide rim will result in a wider but shorter footprint.

The advantages of wider foorprints:
* higher ride heights
* higher peak footprint before rim damage.

Some of course will want to run a lower pressure, which has other advantages:
* generally better traction
* better float on soft surfaces like snow or sand

So yes, you can lower air pressure too much, but generally wider tires (or tire+rim systems) allow for the same protection at lower pressures.


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## pharmaboy (Nov 11, 2005)

spikebike said:


> Wider tires allow lower pressures.
> 
> Imagine a 1" wide tire @ 30 psi vs a 2.4" wide tire @ 30 psi. The 1" wider tire is going to ride much lower and have a very noticeable flat spot. If you tried to ride a 1" tire @ 30 psi on the trail you'd likely snakebike or damage a rim.
> 
> So clearly 2.4" at 30 psi is much better than 1".


Your basic assumption you've made is incorrect . The aspect of the tyre that means you use higher pressure in the small tyre and lower in the larger, is tyre height - ie outside circumference. The 1" tyre is only 1" from dinging the rim (or less). We all know tyres with less size require more pressure, but don't make the assumption at is all a function of width, most is a function of height


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## PretendGentleman (May 24, 2011)

spikebike said:


> Wider tires allow lower pressures.
> 
> Imagine a 1" wide tire @ 30 psi vs a 2.4" wide tire @ 30 psi. The 1" wider tire is going to ride much lower and have a very noticeable flat spot. If you tried to ride a 1" tire @ 30 psi on the trail you'd likely snakebike or damage a rim.
> 
> ...


I think you are generally right, but you are mostly answering an obvious question that is not what this thread is addressing. Yes wider tires have more volume (up to a point), but we are not talking about wider tires, rather we are talking about whether a wider rim has advantages over a narrower rim with the exact same tire.

Also, your assumptions about PSI assume a perfectly rigid casing. We know that tires balloon as you fill them, so if you start with a certain air pressure and then get on the bike, the change in psi will not be the same for 2 different wheel systems, so the contact patch will have a different area. This affect may be small, but it certainly exists.

Your summary points are also incorrect. if a 2.4" tire has approximately a 2.4"*pi=7.5" cross sectional length. A 7.5" rim will result in a very wide contact patch, but pinch flats will be a problem and rider height will be lowered.

This is not a linear system


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## forgiven_nick (Nov 7, 2006)

PretendGentleman said:


> A good way to think about the question of the effect of varying rim width for a particular tire is to consider that there is one particular rim width that will maximize the volume of the tire: the max-volume rim width.


This.


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## Tenuous (Apr 5, 2010)

PretendGentleman said:


> That's a negatory there, feller. Try your math: a 20% reduction in P would cause a 20% rise in V to compensate. That's (1-0.2)*P and (1+0.2)*V in mathspeak. What happens to that so-called constant of yours, C?
> C=PV=[(1-0.2)*P] * [(1+0.2)*V]=0.8*1.2*P*V=.96*P*V=.96*C!=C


aching nutsack, sadly you're right. Just sat down and worked out the math.


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## LittleBitey (Nov 10, 2012)

This thread needs a bong hit, too much math!


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## spikebike (Apr 26, 2007)

pharmaboy said:


> Your basic assumption you've made is incorrect . The aspect of the tyre that means you use higher pressure in the small tyre and lower in the larger, is tyre height - ie outside circumference. The 1" tyre is only 1" from dinging the rim (or less). We all know tyres with less size require more pressure, but don't make the assumption at is all a function of width, most is a function of height


Ugh.

Ok, lets assume identical height. Now compare a 2.4" tire to TWO 2.4" tires. For a given load which will ride higher? It's obvious that the dually setup will handle more weight, right? Just like higher end bike cargo trailers or dually pickup trucks.

Now compare to a 2.4" tire to a 4.8" tire that has identical height (short and fat) and PSI. So they have identical height at zero load. But under say 100 pounds of pressure which will ride higher? The 4.8". Which will handle a higher peak load? The 4.8".

So which will pinch flat first if you take a big drop onto a flat? 2.4".

So if using the same tire rom a 23mm rim (like is standard on the nomad) to a 40mm results in:
* a wider tire
* a higher volume
* riding higher
* higher peak load before a pinch flat (assuming a flat surface)

Make sense?


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## spikebike (Apr 26, 2007)

PretendGentleman said:


> Also, your assumptions about PSI assume a perfectly rigid casing. We know that tires balloon as you fill them, so if you start with a certain air pressure and then get on the bike, the change in psi will not be the same for 2 different wheel systems, so the contact patch will have a different area. This affect may be small, but it certainly exists.
> This is not a linear system


Actually in my experience tires balloon very quickly up to say 15-20 PSI, but very little after. Sure it might not be zero, but I don't see it making nearly the difference that another 20mm of rim adds.

Agreed that it's not a linear system.



PretendGentleman said:


> Your summary points are also incorrect. if a 2.4" tire has approximately a 2.4"*pi=7.5" cross sectional length. A 7.5" rim will result in a very wide contact patch, but pinch flats will be a problem and rider height will be lowered.
> 
> This is not a linear system


I don't quite follow your math or reasoning.

Your tire footprint is a linear system, until the extremes where the rim hits. Weight / pounds_per_square_inch = square_inches of footprint.

So a 7.5" rim will indeed have a very wide contact patch. Assuming 100 pounds per wheel and 30 psi that would be 3.3 square inches. So something like a 7.5" wide x 0.44 inch contact patch.

A 2.4" tire would have something like a 2.4" wide x 1.375" contact patch.

So the longer the contact patch the lower the rim rides... right up till the rim hits.

Imagine you sitting beside the wheel. The 7.5" rim wheel would look like it's barely touching the ground, less than 0.5" would be in contact with the ground.

The 2.4" inch would be visibly flattened at the bottom, with almost an inch and a half.

Now imagine it was 500 pounds per wheel, you need 4x the footprint, the width can't change much, so the length needs to be 4x. The 7.5" rim would be around 2.2", still not very flat. The 2.4" wheel would need be be 7", the rim would be getting noticeably closer to ground.

So basically the wider tires have a much easier time increasing their footprint because of large hits, thus protecting the rim from hitting the ground. Skinnier tires have to elongate their contact patch, which places the rim closer to the ground.


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## smilinsteve (Jul 21, 2009)

spikebike said:


> Ugh.
> 
> Ok, lets assume identical height. Now compare a 2.4" tire to TWO 2.4" tires. For a given load which will ride higher? It's obvious that the dually setup will handle more weight, right? Just like higher end bike cargo trailers or dually pickup trucks.
> 
> ...


The fact is that rim width does not increase ride height the way you assume. 
I posted examples earlier. How much pressure decrease can you take if the height of the tire is less than 1mm taller?
Ugh?


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## spikebike (Apr 26, 2007)

smilinsteve said:


> The fact is that rim width does not increase ride height the way you assume. I posted examples earlier.


I've read the thread, but I'll have to look for which post you mean. Tire height it set by the manufacturer. The threads in the casing do not stretch significantly, so the TIRE
height changes minimally with a wider rim.

But the RIDE height changes directly with width. The wider the footprint the shorter it is. The shorter the footprint the higher the ride height. Did your post discuss tire height? Or ride height?



smilinsteve said:


> How much pressure decrease can you take if the height of the tire is less than 1mm taller?
> Ugh?


It's quite simple to calculate. What two tire widths did you want to compare? Seems like the common comparisons I see are in the range of 5-10mm wider when going from a 20-25mm wide rim to a 40mm or so wide rim.


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## smilinsteve (Jul 21, 2009)

spikebike said:


> Actually in my experience tires balloon very quickly up to say 15-20 PSI, but very little after. Sure it might not be zero, but I don't see it making nearly the difference that another 20mm of rim adds.
> 
> Agreed that it's not a linear system.
> 
> ...


You missed the point. The 7.5 inch rim means the tire is flat against the ground.


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## smilinsteve (Jul 21, 2009)

spikebike said:


> I've read the thread, but I'll have to look for which post you mean. Tire height it set by the manufacturer. The threads in the casing do not stretch significantly, so the TIRE
> height changes minimally with a wider rim.
> 
> But the RIDE height changes directly with width. The wider the footprint the shorter it is. The shorter the footprint the higher the ride height. Did your post discuss tire height? Or ride height?
> ...


Your assumption is that a wider rim results in a wider contact patch. I'm not buying it. A wider rim doesn't make the tire wider.


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## ebenke (Sep 1, 2008)

smilinsteve said:


> Your assumption is that a wider rim results in a wider contact patch. I'm not buying it. A wider rim doesn't make the tire wider.


I have a new set of the 'wider' wheels, and yes the tire's contact patch is in fact wider than it was on the narrow hoop. Problem solved, your welcome.

EBenke


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## pharmaboy (Nov 11, 2005)

spikebike said:


> Ugh.
> 
> Ok, lets assume identical height. Now compare a 2.4" tire to TWO 2.4" tires. For a given load which will ride higher? It's obvious that the dually setup will handle more weight, right? Just like higher end bike cargo trailers or dually pickup trucks.
> 
> ...


Answers in bold.

The point is moot anyway, as the tyres we are talking about are not of the same circumference because they are balloons not low profile belted car tyres - so a wider tyre is indeed taller than a narrower tyre

A rounder fatter contact patch is just a different contact patch but it could be argued that if the strike is say the edge of a gutter perpendicular to the wheel, then there might be more pressure available at that shape of hit versus a point load (sharp rock).

Fat bike riders seem to use just a little more than 1/2 of what a normal rider uses and their tyres seem to be nearly twice as wide - I've raced 1.9s which need at least 30psi and 2.25s I set to 25 or 26. That seems ballpark to agree with the predicted outcome from the physics and engineers perspective, ie .3/2 is about a 15% height difference - corresponds remarkably close to that psi difference required.

I'm sure width can play some role, so I shouldn't be absolute, but is suspect you are yay overestimating it in the real Mtb world with round tyres


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## smilinsteve (Jul 21, 2009)

ebenke said:


> I have a new set of the 'wider' wheels, and yes the tire's contact patch is in fact wider than it was on the narrow hoop. Problem solved, your welcome.
> 
> EBenke


Really? How did you measure that?

I figure that a loaded tire is going to flatten so that the outermost knobs are on the ground. That's the widest it can get, unless you want to start rolling on your side walls.

The rim width won't effect that. A wide rim can't make the tire wider. It increases the volume and changes the inflated shape, but the contact patch width is fixed by the tread width of the tire.


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## Mountain Cycle Shawn (Jan 19, 2004)

Tire volumn and contact patch is increased with a wider rim. But, the change is so small, it's insignificant and its not what makes wider rims better.


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## PretendGentleman (May 24, 2011)

Mountain Cycle Shawn said:


> Tire volumn and contact patch is increased with a wider rim. But, the change is so small, it's insignificant and its not what makes wider rims better.


NO you have not read the last 2 pages, clearly. A 7.5" wide rim with a 2.3" tires isn't going to have as much volume as a 2" rim with a 2.3" tire. Unless you are contesting that observation...


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## Mountain Cycle Shawn (Jan 19, 2004)

PretendGentleman said:


> NO you have not read the last 2 pages, clearly. A 7.5" wide rim with a 2.3" tires isn't going to have as much volume as a 2" rim with a 2.3" tire. Unless you are contesting that observation...


Get back to me when you can get a 2.3" tire in a 7.5" rim. Obviously, as with other things in life there is a point where an idea that is blown out of proportion, just doesn't work anymore. What most people are talking about is taking a tire off a narrow rim and putting that same tire on a wider rim. No different tire sizes, or rims that don't exist bull ****. Stop living in a, "Pretend" world.


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## pharmaboy (Nov 11, 2005)

Mountain Cycle Shawn said:


> Tire volumn and contact patch is increased with a wider rim. But, the change is so small, it's insignificant and its not what makes wider rims better.


Heh, have you been convinced Shawn to change your position slightly?

I might be nitpicking a bit though - size of the contact patch is entirely a question of differing pressure, it's the shape of the contact patch that changes, specifically slightly wider and shorter, but your overall point stands, it's a tiny change and likely not what makes the rim perform differently. (This is without taking into account knobs which will make the question differ depending on the model tyre and pressure that you are measuring at)

Interesting there is so much discussion on this topic when hardly anyone does anything much more than squeeze their tyres with their thumbs then goes out and rides (1 or 2 psi would make bigger differences than those discussed here - either good or bad)


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> Heh, have you been convinced Shawn to change your position slightly?
> 
> I might be nitpicking a bit though - size of the contact patch is entirely a question of differing pressure, it's the shape of the contact patch that changes, specifically slightly wider and shorter, but your overall point stands, it's a tiny change and likely not what makes the rim perform differently. (This is without taking into account knobs which will make the question differ depending on the model tyre and pressure that you are measuring at)
> 
> Interesting there is so much discussion on this topic when hardly anyone does anything much more than squeeze their tyres with their thumbs then goes out and rides (1 or 2 psi would make bigger differences than those discussed here - either good or bad)


It depends how you look at it. For me, with the same tire, I'm running a lot lower pressure on the wider rim. So, my volumn has not increased. If you're running the same psi you might get a slight increase. But, not enought to make a difference.


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## spikebike (Apr 26, 2007)

smilinsteve said:


> You missed the point. The 7.5 inch rim means the tire is flat against the ground.


Ha, sorry, totally misunderstood you. I thought the non-linear comment was about tire size not increasing linearly with air pressure.

So yes you can have a rim that's too wide for a tire. But the problems you mention don't happen in normal ranges. The rest of the world (road bikes, motorcycles, cars) uses tires 20-50% wider than the rim. I'd expect the "wider = better" trend to continue from todays common 2-3x (mtb tire vs rim) as wide as a rim down to the 20-50% range.


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## spikebike (Apr 26, 2007)

smilinsteve said:


> Your assumption is that a wider rim results in a wider contact patch. I'm not buying it. A wider rim doesn't make the tire wider.


Actually that's exactly what it does. It does not however make the tire taller.


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## spikebike (Apr 26, 2007)

smilinsteve said:


> Really? How did you measure that?
> 
> I figure that a loaded tire is going to flatten so that the outermost knobs are on the ground. That's the widest it can get, unless you want to start rolling on your side walls.


I agree that the optimal knobby pattern will change for say a 20mm rim vs a 40mm rim. But the accounts I've heard claim 5-10mm wider tire when upgrading to a wider rim. Say you buy a 2.4" tire that's approximately 2.4" wide when mounted on a 20-25mm rim. If it's more like 2.6" when mounted on a 40mm rim that's not that big a difference.



smilinsteve said:


> The rim width won't effect that. A wide rim can't make the tire wider. It increases the volume and changes the inflated shape, but the contact patch width is fixed by the tread width of the tire.


Pictures I've seen with people measuring with calibers show that in fact the tire is wider.

Tire width does have a maximum, but if you are trying to exceed that you are under inflated. I'd expect wider rims to have a squarer footprint that's shorter and wider than a skinny rim. Even if it's the same at maximum widgth I'd expect the skinnier rim to taper more quickly.


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## Mountain Cycle Shawn (Jan 19, 2004)

The wider contact patch comes from the fact that most people with wider rims run lower pressure. Most tires don't get measurableably wider. But the edge knobs stand up higher and the top of the tire wants to flatten out. The tire does not get any taller.


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## pharmaboy (Nov 11, 2005)

spikebike said:


> I agree that the optimal knobby pattern will change for say a 20mm rim vs a 40mm rim. But the accounts I've heard claim 5-10mm wider tire when upgrading to a wider rim. Say you buy a 2.4" tire that's approximately 2.4" wide when mounted on a 20-25mm rim. If it's more like 2.6" when mounted on a 40mm rim that's not that big a difference.
> 
> Pictures I've seen with people measuring with calibers show that in fact the tire is wider.
> 
> Tire width does have a maximum, but if you are trying to exceed that you are under inflated. I'd expect wider rims to have a squarer footprint that's shorter and wider than a skinny rim. Even if it's the same at maximum widgth I'd expect the skinnier rim to taper more quickly.


1st para - read this

29er Tires on Different Rim Width Comparison

25 to 35mm increases width by approximately 1mm , so a 2.4 tyre changes to around a 2.42 tyre or something (can't be arsed to do the maths right now, but it's buggar all)

The main thread on this subject that has heaps of properly technical answers, and also makes sure people understand that belted car and motorbike tyres are totally different animals is referenced every couple of pages here, and really needs to be read by all


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## ebenke (Sep 1, 2008)

smilinsteve said:


> Really? How did you measure that?
> 
> I figure that a loaded tire is going to flatten so that the outermost knobs are on the ground. That's the widest it can get, unless you want to start rolling on your side walls.
> 
> The rim width won't effect that. A wide rim can't make the tire wider. It increases the volume and changes the inflated shape, but the contact patch width is fixed by the tread width of the tire.


I didn't say the tire got wider. I said the contact patch got wider. The wider wheel actually widens the contact patch. The contact patch is not fixed by the width of the tire.

EBenke


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## J.B. Weld (Aug 13, 2012)

Is there really anyone out there breaking out calipers and dyes to measure and compare different contact patches between various tire/rim width combinations?


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## Mountain Cycle Shawn (Jan 19, 2004)

ebenke said:


> I didn't say the tire got wider. I said the contact patch got wider. The wider wheel actually widens the contact patch. The contact patch is not fixed by the width of the tire.
> 
> EBenke


Finally someone with some common sense!


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## eb1888 (Jan 27, 2012)

Inflation pressure helps determine contact patch at any point of a tire's interaction with the trail surface-- climbing at slow speed, or hitting a rock, or landing a jump.
You set the pressure to avoid rim hits at the most tire challenging point for a ride so you can make it through without damage.
Wide rims increase volume. You need less pressure to avoid the rim hit point.
The tire can deform more before it reaches that point. From that added deformation relative to the same tire on a skinny rim at the same point along the trail comes a larger contact patch and more performance.
Tire rollover is more dramatic. A wide rim gives the sidewall support it just doesn't get at all with a skinny rim. Instead you can get abrupt tire rollover with a sudden loss of traction that can put you on the ground. When you don't have to deal with that it's possible to recover within the time you get as traction is lost more gradually from a higher rollover threshold.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> It depends how you look at it. For me, with the same tire, I'm running a lot lower pressure on the wider rim. So, my volumn has not increased. If you're running the same psi you might get a slight increase. But, not enought to make a difference.


In other words, its lower pressure you like, not wide rims.


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## smilinsteve (Jul 21, 2009)

J.B. Weld said:


> Is there really anyone out there breaking out calipers and dyes to measure and compare different contact patches between various tire/rim width combinations?


No, but there are people out there pretending they know the length and width of their contact patches.


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## smilinsteve (Jul 21, 2009)

ebenke said:


> I didn't say the tire got wider. I said the contact patch got wider. The wider wheel actually widens the contact patch. The contact patch is not fixed by the width of the tire.
> 
> EBenke


Explain how the contact patch can be wider than the measurement of the total tread rubber width from outside lug to outside lug. Thanks.


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## smilinsteve (Jul 21, 2009)

eb1888 said:


> Inflation pressure helps determine contact patch at any point of a tire's interaction with the trail surface-- climbing at slow speed, or hitting a rock, or landing a jump.
> You set the pressure to avoid rim hits at the most tire challenging point for a ride so you can make it through without damage.


Right so far, but..



> Wide rims increase volume. You need less pressure to avoid the rim hit point.
> The tire can deform more before it reaches that point. From that added deformation relative to the same tire on a skinny rim at the same point along the trail comes a larger contact patch and more performance.


Wide rims do increase volume, but they do not significantly increase tire height, and more volume does nothing to improve resistance to pinch flats assuming equal pressure. And I do not know what you are getting at with your "added deformation" concept.



> Tire rollover is more dramatic. A wide rim gives the sidewall support it just doesn't get at all with a skinny rim. Instead you can get abrupt tire rollover with a sudden loss of traction that can put you on the ground. When you don't have to deal with that it's possible to recover within the time you get as traction is lost more gradually from a higher rollover threshold.


I'm still thinking about this idea, but most models I have seen on the subject give little or no credit to the tire structure for the support the tire gives. It all comes from the air pressure, and therefore moving out the sidewall does not matter.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> The wider contact patch comes from the fact that most people with wider rims run lower pressure. Most tires don't get measurableably wider. But the edge knobs stand up higher and the top of the tire wants to flatten out. The tire does not get any taller.


Regardless of rim size, the "top of the tire wants to flatten out". 
Any mountain bike tire on any width rim is flattening across its total tread width unless it is pumped up so much that it can't, which more of a road tire scenario.


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## eb1888 (Jan 27, 2012)

smilinsteve said:


> most models I have seen on the subject give little or no credit to the tire structure for the support the tire gives. It all comes from the air pressure, and therefore moving out the sidewall does not matter.


Maybe by visualizing the shape of the tire on two different width rims it can be easier to think about how a wider rim will allow the sidewall to help make the tire more difficult to wiggle side to side. More force would be needed the wider the tire beads were separated until you wouldn't be able to push the tire at the tread side to side at all. Whereas when the two beads are brought together and touch you can easily move it back and forth. That difference in washout threshold is significant when I'm riding.


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## smilinsteve (Jul 21, 2009)

spikebike said:


> I agree that the optimal knobby pattern will change for say a 20mm rim vs a 40mm rim. But the accounts I've heard claim 5-10mm wider tire when upgrading to a wider rim. Say you buy a 2.4" tire that's approximately 2.4" wide when mounted on a 20-25mm rim. If it's more like 2.6" when mounted on a 40mm rim that's not that big a difference.
> 
> Pictures I've seen with people measuring with calibers show that in fact the tire is wider.
> 
> Tire width does have a maximum, but if you are trying to exceed that you are under inflated. I'd expect wider rims to have a squarer footprint that's shorter and wider than a skinny rim. Even if it's the same at maximum widgth I'd expect the skinnier rim to taper more quickly.


I think the wider caliper measurements you have seen are are max width of the sidewall bulge, not tread width, and definitely not contact patch width.


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## Guest (Mar 28, 2015)

spikebike said:


> Wider tires allow lower pressures.


No, taller tires allow lower pressures. As it turns out, wider and taller are the same thing with bicycle tires so what you say is true only by coincidence.



spikebike said:


> Similar rules apply when you use a wider rim instead of a wider tire.


This is where you get into trouble. A wider rim does not produce a taller tire so "similar rules" do not apply.



spikebike said:


> The same 2.4" tire will have a wider footprint and a higher ride height when used with a wider rim.


No, it won't. You should try measuring this.



spikebike said:


> So yes, you can lower air pressure too much, but generally wider tires (or tire+rim systems) allow for the same protection at lower pressures.


No, they don't. Wider rims allow lower pressures only when sidewall squirm is the limiting factor.


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## Guest (Mar 28, 2015)

spikebike said:


> Now compare to a 2.4" tire to a 4.8" tire that has identical height (short and fat) and PSI.


You don't seem to understand how bicycle tires work. Height and width are NOT independent. There is no such thing as a 4.8" tire that is the same height as a 2.4" tire, not even hypothetically.



spikebike said:


> So they have identical height at zero load. But under say 100 pounds of pressure which will ride higher? The 4.8". Which will handle a higher peak load? The 4.8".


You are wrong on both accounts. This depends on the pressures of the two tires and that's not stated.



spikebike said:


> Make sense?


No, not remotely.

A wider rim increases the width of the mounted casing and therefore the air volume inside the tire. Neither of these things matter one bit.


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## JLF1200 (Sep 16, 2009)

Mr.P said:


> Sigh... DH rims have always been the widest rims available - for decades, until the last year or two. Why is that? According to you, just to look pretty (no benefit).
> 
> And here come the wide/tubeless/carbon DH rims you and others can't wrap your head around:
> 
> ...


Do you have any clue what the inner width is on that rim? By the look of it, I'm guessing <27mm.

Meanwhile, 
7 Downhill Bike Checks - Crankworx Rotorua - Pinkbike
and
4 Downhill Bike Checks - Crankworx Rotorua - Pinkbike

Everyone is pretty much still running 23mm-25mm inner width DH wheels. Including the winner and all of the serious WC contenders. The widest rim I can find in the bike checks coming in from Rotorua would probably be the Bontrager prototype wheels that the Trek team is using, which are 27mm inner width.

And here's another real-world data point:
Prototype Michelin Tire - PIT BITS - Crankworx Rotorua - Mountain Biking Pictures - Vital MTB

In the entire start list for the pro enduro race, you couldn't find better DH pedigree than in Jerome Clemetz and Nico Vouilloz-- who are both running freshly minted prototype tires... on 23mm inner width rims.


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## SDMTB'er (Feb 11, 2014)

JLF1200 said:


> Do you have any clue what the inner width is on that rim? By the look of it, I'm guessing <27mm.
> 
> Meanwhile,
> 7 Downhill Bike Checks - Crankworx Rotorua - Pinkbike
> ...


There were a lot of flats in rotorua this year - wonder if there is a correlation with rim width.


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## Zowie (Aug 3, 2013)

J.B. Weld said:


> Is there really anyone out there breaking out calipers and dyes to measure and compare different contact patches between various tire/rim width combinations?


I wouldn't think so.

Facts are antithetical to the average armchair engineer... unless they can be wildly misinterpreted for entertaining hypotheses.


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## mazspeed (Oct 17, 2004)

I did a simple test with the tires. I have 2 pair of rims, both 27.5 with 2.4 maxxis tires. One are on the derby's, and one on a set of enduro i9's. I think the inner difference in width is about 18mm or so, the derby's being the wider rims. Pumping them up to 20lbs each I notice 2 things. 1. The derby's seem to be more progressive when you put weight on them. Which means to me, the more you push on them, the more they push back at the same lbs. Which seems to make me think that you can run lower pressures without damage since it seems like there is more air to push back. Does this make sense to anyone? 
2. when you lean on both tires, I did so with my fox fork an interesting thing happened. More tread hit the ground. The outer edges were almost flat on the ground at 20psi. The tires didn't really seem wider, ( I did not measure) but the tread did. When I put them on the enduro rim, and did the same thing, the outer tread were touching the ground, but barley. It seems as if I had a much flatter tread on the ground. Does that make any sense?
Ok, this was something I did to see if there was any difference in tire width. This was in no way any kind of scientific test of any kind. I was just mucking about. Now how this equates to the real world on my bike when I will start riding it, who knows, but there is absolutely a tread difference on the ground with weight being applied. Hope this helps and I hope someone can explain it to me how this may be better or worse in real world riding and not in forum arguments.


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## smilinsteve (Jul 21, 2009)

mazspeed said:


> 1. The derby's seem to be more progressive when you put weight on them. Which means to me, the more you push on them, the more they push back at the same lbs. Which seems to make me think that you can run lower pressures without damage since it seems like there is more air to push back. Does this make sense to anyone?


No.


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## mazspeed (Oct 17, 2004)

smilinsteve said:


> No.


I guess you will to try it for yourself.


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## Mountain Cycle Shawn (Jan 19, 2004)

mazspeed said:


> I did a simple test with the tires. I have 2 pair of rims, both 27.5 with 2.4 maxxis tires. One are on the derby's, and one on a set of enduro i9's. I think the inner difference in width is about 18mm or so, the derby's being the wider rims. Pumping them up to 20lbs each I notice 2 things. 1. The derby's seem to be more progressive when you put weight on them. Which means to me, the more you push on them, the more they push back at the same lbs. Which seems to make me think that you can run lower pressures without damage since it seems like there is more air to push back. Does this make sense to anyone?


I say a 100% yes to this. This has been my experience. ESPECIALLY, if you are running the same psi as you were with the narrow rims. I'm running 10psi lower and this is still a yes for me.


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## beanbag (Nov 20, 2005)

mazspeed said:


> I did a simple test with the tires. I have 2 pair of rims, both 27.5 with 2.4 maxxis tires. One are on the derby's, and one on a set of enduro i9's. I think the inner difference in width is about 18mm or so, the derby's being the wider rims. Pumping them up to 20lbs each I notice 2 things. 1. The derby's seem to be more progressive when you put weight on them. Which means to me, the more you push on them, the more they push back at the same lbs. Which seems to make me think that you can run lower pressures without damage since it seems like there is more air to push back. Does this make sense to anyone?
> 2. when you lean on both tires, I did so with my fox fork an interesting thing happened. More tread hit the ground. The outer edges were almost flat on the ground at 20psi. The tires didn't really seem wider, ( I did not measure) but the tread did. When I put them on the enduro rim, and did the same thing, the outer tread were touching the ground, but barley. It seems as if I had a much flatter tread on the ground. Does that make any sense?


Yes, this does make sense, see:

Wide Rims? Don't believe the hype... - Page 22- Mtbr.com

Comparing the same tire on a wide vs narrow rim when both have been compressed almost to the point that the rim touches the ground (pinch flat). When the rim is wider, the tire "flat spot" is wider in profile as well, since....
Well, lemme put it this way. 
Assume that in cross section view, the total arc length of the tire is fixed from bead to bead. Then when the rim is wider, that is like "unrolling" the tire, or put another way, less arc length / sidewall is wasted from having to travel from the edge of the bulge back to the rim bead hooks. So with a wide rim, the flat spot is wider as well, and wider flat spot means bigger contact patch, means more total force pushing back against the ground.

This view is really an oversimplification since it doesn't take into account all the weird stuff that happens because the tire casing is not stretchy, nor takes into account what happens in the other third dimension, but at least qualitatively it "makes sense".


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## libertybike (Mar 12, 2015)

*Actually yes*



smilinsteve said:


> No.


Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims. You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.

WIDE rims

from the link

WIDE RIMS CHANGE TO TIRE SIZE:
Going to wider rims, the tire's circumference doesn't grow taller. I've closely measured rollout curcumference which calculates to tire height, and measured knob width too. Using the same 2.3 Pacenti neo-moto tire on a 650b x 40mm Derby Rims compared to a 28mm Blunt, the tire doesn't grow taller, the tire is no higher at the center knobs, and the edge knobs are actually a very small measurement narrower, about 0.0225 inch or 0.6 mm narrower. But the edge knobs do "stand up" a little higher making a more "square" tread profile, and these edge knobs do come closer to the arch of a fork or yoke of a chain-stay by about 1.5mm, so it is slightly closer clearance above the edge knobs.


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## Mountain Cycle Shawn (Jan 19, 2004)

libertybike said:


> Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims. You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.
> 
> WIDE rims
> 
> ...


Ummm, if you'll read what you posted. Ray actually claims that the edge knobs are narrower, but stand up higher. If you read the link that you posted it says that the sidewalls are wider with a wider rim, which makes sense. No where does it say that the tire width at the tread is any wider with a wider rim. You can't stretch the tread of a tire, with a wider rim. The only thing you can do is change its profile. But, all of this has very little or nothing to do with why wide rims work better. It has everything to do with the fact that a wider rim allows the tire to better deal with the forces acting upon it, and nothing else. Some tires will gain a bit better tread profile and some tires will get a worse tread profile with wider rims.


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## smilinsteve (Jul 21, 2009)

libertybike said:


> Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims. You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.
> 
> WIDE rims
> 
> ...


You obviously don't know who you are talking to, bub :lol:


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## smilinsteve (Jul 21, 2009)

libertybike said:


> Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims.


I'm ALL about the facts sir. 
I don't think tread width gets wider, or contact patch gets wider, but the contact patch thing is more complicated. max width (sidewall bulge) gets wider.



> You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.


You obviously have poor reading comprehension skills, as your quote from Derby proves, contradicting the point you thought it made. But you also have misread my posts. I don't claim that wider rims "do nothing". I am just challenging some of the reasoning that people are using to explain the benefits they feel. And I have ridden wide rims. I was riding them in 1988!


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## libertybike (Mar 12, 2015)

Mountain Cycle Shawn said:


> Ummm, if you'll read what you posted. Ray actually claims that the edge knobs are narrower, but stand up higher. If you read the link that you posted it says that the sidewalls are wider with a wider rim, which makes sense. No where does it say that the tire width at the tread is any wider with a wider rim. You can't stretch the tread of a tire. The only thing you can do is change its profile. But, all of this has very little or nothing to do with why wide rims work better. It has everything to do with the fact that a wider rim allows the tire to better deal with the forces acting upon it, and nothing else. Some tires will gain a bit better tread profile and some tires will get a worse tread profile with wider rims.


I never said the sidewalls were wider in my post did I? I wasn't specific in my post to what I meant about "Wider Tires" but if you look at the link it is pretty obvious what I am talking about is it not? However he actually does say the tires are wider where it matters right here:

"But the edge knobs do "stand up" a little higher making a more "square" tread profile, and these edge knobs do come closer to the arch of a fork or yoke of a chain-stay by about 1.5mm, so it is slightly closer clearance above the edge knobs."

The profile being more "Square" is exactly what I am talking about. It makes the profile of the tire wider. The edge nobs are closer to the fork or the yoke because they are flaring out more and the measurement he does shows that the edge nobs are doing just that. The tire didn't get wider but it does widen the tread (edge nobs) which is why they are flaring up. When on the trail the edge nobs are now being utilized more and that is what he is talking about in that post.

The measurements are right here on his page and it is pretty clear that it is wider:

"Tire measured on 40mm wide rim, edge knobs stand up and flair very slightly less to the sides"

Width measurement from the knobs = 2.35

as compared to the other 28mm wide rims which are measuring at 2.33.

So yes the tire itself isn't going to grow in size, but it does widen the profile of the tread by moving the edge nobs closer to the contact patch on the trail.

He even says this on the same exact page, he says exactly what I just said here:

"Cornering traction is much improved on dusty hardpack to very loose gravelly dirt or loamy covered with leaves, as a result of this combination of flatter tread cross section, stiffer edge knobs, more knobs in contact, and lower air pressure, all enabled with wide rims."

Cornering traction is better because of increased contact on the trail from the edge nobs being utilized more.

Maybe wider is a bad word to use but what is a better word for what is going on with the edge nobs and the "Squaring" of the tire profile? I guess the best way to put this is that the wider rims do increase the width of the contact patch (atleast according to Derby it does) by actually pushing the edge nobs closer to the contact patch of the tire.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> No where does it say that the tire width at the tread is any wider with a wider rim. You can't stretch the tread of a tire. The only thing you can do is change its profile. But, all of this has very little or nothing to do with why wide rims work better. It has everything to do with the fact that a wider rim allows the tire to better deal with the forces acting upon it, and nothing else. Some tires will gain a bit better tread profile and some tires will get a worse tread profile with wider rims.


Yes I think there is something about the way the sidewall reacts to forces that changes with the profile change. I wish I understood it, but I don't. The only article I can find on the subject is by Richard Cunningham, and it is a pretty awful explanation.

I think the reasoning that is going around this thread, e.g. wider tire, wider contact patch, lower pressure, more volume to absorb forces, etc, are pretty much all wrong.


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## Mountain Cycle Shawn (Jan 19, 2004)

libertybike said:


> I never said the sidewalls were wider in my post did I? I wasn't specific in my post to what I meant about "Wider Tires" but if you look at the link it is pretty obvious what I am talking about is it not? However he actually does say the tires are wider where it matters right here:
> 
> "But the edge knobs do "stand up" a little higher making a more "square" tread profile, and these edge knobs do come closer to the arch of a fork or yoke of a chain-stay by about 1.5mm, so it is slightly closer clearance above the edge knobs."
> 
> ...


The edge knobs STAND UP more. He's talking about height, not width. The fork crown is a three dimensional object. But, obviously they don't stand up higer than the middle of the tire. Each tire is going to be slightly different on a wider rim. If your hanging your hat on a .02" increase in tire width, then your are missing the point. Again, refer back to post # 812 as to why wider rims work better. It's not your small increase, if any, in tire width. The only reason Ray gets that much into the tire dimensions is so people won't think that they can't use these rims because they are affraid the tires won't fit in the bike.


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## libertybike (Mar 12, 2015)

Mountain Cycle Shawn said:


> The edge knobs STAND UP more. He's talking about height, not width. The fork crown is a three dimensional object. But, obviously they don't stand up higer than the middle of the tire. Each tire is going to be slightly different on a wider rim. If your hanging your hat on a .02" increase in tire width, then your are missing the point. Again, refer back to post # 812 as to why wider rims work better. It's not your small increase, if any, in tire width. The only reason Ray gets that much into the tire dimensions is so people won't think that they can't use these rims because they are affraid the tires won't fit in the bike.


Sorry but you are just ignoring what he says himself on his website. So I will repost his exact words:

"*Cornering traction* is much improved on dusty hardpack to very loose gravelly dirt or loamy covered with leaves, *as a result* of this combination of *flatter tread cross section*, *stiffer edge knobs, more knobs in contact, and lower air pressure*, all enabled with wide rims."

Flatter is a better word to use, it makes the tire flatter and thus more knobs in contact with the trail. That does make a difference hints why he has it on his site. The lower air pressure is 1 component of that also but not the only one.


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## Mountain Cycle Shawn (Jan 19, 2004)

Another thing to consider. Wider rims don't stretch a tire. Higher psi will. Most people are running a lot lower psi with wider rims, a lot lower. Which will take away any small increase in tire width, if any, caused by a wider rim.


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## Mountain Cycle Shawn (Jan 19, 2004)

libertybike said:


> Sorry but you are just ignoring what he says himself on his website. So I will repost his exact words:
> 
> "*Cornering traction* is much improved on dusty hardpack to very loose gravelly dirt or loamy covered with leaves, *as a result* of this combination of *flatter tread cross section*, *stiffer edge knobs, more knobs in contact, and lower air pressure*, all enabled with wide rims."
> 
> Flatter is a better word to use, it makes the tire flatter and thus more knobs in contact with the trail. That does make a difference hints why he has it on his site. The lower air pressure is 1 component of that also but not the only one.


Dude, where does it say anything about tire width? Tire width doesn't make wide rims better.


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## Mountain Cycle Shawn (Jan 19, 2004)

If tire width was that important, then people would just be putting bigger and bigger tires on. The bigger tires caused this problem. That's what people thought would be better. That's what caused the need for wide rims. To get rid of the lightbulb shape of a narrow rim and wide tire. The idea is to get away from that and have more of a dirt bike rim/tire profile.


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## libertybike (Mar 12, 2015)

Mountain Cycle Shawn said:


> Dude, where does it say anything about tire width? Tire width doesn't make wide rims better.


Who said anything about tire width making rims better? Wider rims enable the bottom of your tires to have a wider contact patch. Try reading the quote again.

"Cornering traction is much improved on dusty hardpack to very loose gravelly dirt or loamy covered with leaves, as a result of this combination of flatter tread cross section, stiffer edge knobs, more knobs in contact, and lower air pressure, *all enabled with wide rims."*

And he says it again here:

"The* wider sidewall *raises the edge knobs without raising the center knobs, which makes a *less round or more "square" tread *cross-section profile."


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## Mountain Cycle Shawn (Jan 19, 2004)

Actually with some tires the tread flattens out and you get less tread on the ground in the corners. Some tires don't work well with a wider rim. Some tires won't even stay on these rims at all.


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## Mountain Cycle Shawn (Jan 19, 2004)

libertybike said:


> Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims. You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.
> 
> WIDE rims
> 
> ...


 Because you keep talking tire width. What am I supposed to believe that your tire width rampage here is suppose to mean that you think it's not what makes them work better.


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## libertybike (Mar 12, 2015)

Mountain Cycle Shawn said:


> Because you keep talking tire width. What am I supposed to believe that your tire width rampage here is suppose to mean that you think it's not what makes them work better.


Yes because of the wider rims "The wider sidewall raises the edge knobs without raising the center knobs, which makes a less round or more "square" tread cross-section profile." -Derby


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## ebenke (Sep 1, 2008)

This thread has become pretty much worthless banter. There are those with wider wheels and they know how it affects the tires. And then there are those who are cynical but have never tried them. Then there are the engineering types who have proved and disproved wide wheels with some mathematical equations. Yep this thread has run its course.


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## J.B. Weld (Aug 13, 2012)

After 33 pages, thousands of wise words and sage advice, much careful consideration and deliberation, then weighing in all contributing factors I've concluded that for now I'm not believing the hype.


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## pharmaboy (Nov 11, 2005)

libertybike said:


> Don't let facts or measurements get in the way of your thinking though. Tire width has been measured with wider rims and tire width is wider with wider rims. You can argue in speculation land all you want since you have 0 real facts in your posts it is just your opinion. You haven't tried wider rims and you haven't measured wider rims, but somehow you know that they don't do anything? LOL OK. Well other people have done the measurements and tried them.
> 
> WIDE rims
> 
> ...


Regardless of whether it may or may not be true, are you not even slightly weary of taking your evidence from an individual that has as their product a super wide rim?

It's liking linking to Coke for proof of the healthiness of their products


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## Mountain Cycle Shawn (Jan 19, 2004)

J.B. Weld said:


> After 33 pages, thousands of wise words and sage advice, much careful consideration and deliberation, then weighing in all contributing factors I've concluded that for now I'm not believing the hype.


It's your loss. It's not hype. They make every situation in my riding world a lot better and lighter. It's the single best thing I have done to my bike!


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## Mountain Cycle Shawn (Jan 19, 2004)

I take that back. It's the single best thing I've done to any bike and I've had a lot of them.


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## Mountain Cycle Shawn (Jan 19, 2004)

pharmaboy said:


> Regardless of whether it may or may not be true, are you not even slightly weary of taking your evidence from an individual that has as their product a super wide rim?
> 
> It's liking linking to Coke for proof of the healthiness of their products


Ray is a very honest and stand up guy. He has more experience than most of us put together. What he says is true, in his experience. People just interperate what he says differently. Wide rims are here to stay. The big tire companies are already making tires for wider rims.


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## libertybike (Mar 12, 2015)

pharmaboy said:


> Regardless of whether it may or may not be true, are you not even slightly weary of taking your evidence from an individual that has as their product a super wide rim?
> 
> It's liking linking to Coke for proof of the healthiness of their products


I was weary yes, you are right. I did a lot of research online about wider rims and those who have tried them. There dozens of reviews online on both Derby and IBIS rims that are 40-41mm in width. What ultimately led me to believing all the hype online on forums and reviews I noticed IBIS had endorsed Derby's idea completely on their website and IBIS may not be the most respected in the industry but they are a very respectable company. They have now shifted to wide rims endorsing Derby right on their website here:

We're not the first people to discover the wide rim advantages. The early mountain bikers as mentioned above had it right. Back in 2011, Richard Cunningham, the Pinkbike.com tech guru wrote an article called "Wider Rims Are Better" in his Pinkbike Tech Tuesday Series. RC had it right, and we encourage you to read the article. In 2012 Richard wrote about the Syntace W35 MX 35mm wide aluminum rims, once again beating the wide rim drum.
In 2013 the first wide carbon fiber rims came out, called Derby Rims. Derby is our good friend and in fact Ibis liked his idea so much we funded half the original tooling expense of these rims. Having access to the Derby Rims proved invaluable in testing for our own concepts and designs. Derby's rims are made in a different factory than ours, as we will be needing a much larger quantity than his source can provide.
For now, we will only be selling complete wheels, so if you're looking for rims only, we heartily endorse the product that Derby is selling. If you can get them that is, Derby Rims have been regularly selling out each production run.

http://www.ibiscycles.com/wheels/

Also if you check their website they are selling many of their enduro/downhill style bikes with IBIS 741 wheels, which are 41mm wide. Putting their money where their mouth is to sell bikes stock with these new wheels.


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## smilinsteve (Jul 21, 2009)

libertybike said:


> Yes because of the wider rims "The wider sidewall raises the edge knobs without raising the center knobs, which makes a less round or more "square" tread cross-section profile." -Derby


It is true that the unloaded profile is more square. It is also true that raising the edge knobs would widen the contact patch, ONLY IF the tire pressure was high enough to prevent the flattening of the tire completely from edge to edge under a normal riding load. The whole idea of wider rims = wider contact patch came (I think) from the road tire world where pressures are very high and there are no knobs reaching for the ground. In that world, a flatter profile does widen the contact patch.

It is my thought that normal tire pressure in tubeless MTB tires these days, even on narrow rims, allows the tire to flatten across the total tread width, in which case a wider rim can do nothing to increase the contact patch width.

One final thought. As mentioned before, your argument for the benefit of wide rims comes from an advertisement for wide rims. Nothing against Derby. I have read a lot of his posts on this subject. Sometimes I agree, sometimes not, but regardless, he is selling wide rims.


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## Mountain Cycle Shawn (Jan 19, 2004)

I just got back from a ride and I can't wipe the silly grin off my face. Lighter wheels, much more control and grip, wheels that look very cool. What more could I ask for from a set of wheels. Each ride gets better as I explore their limits. I'm pretty sure these wheels limits are much more than my limits are. And, just for the record, my WTB Mutano Raptors are only wider in the sidewall. The tread is not wider, but the edge knobs stand up about 3mm higher vertically, toward the top of the fork arch, but not out to the side.


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## smilinsteve (Jul 21, 2009)

beanbag said:


> Yes, this does make sense, see:
> 
> Wide Rims? Don't believe the hype... - Page 22- Mtbr.com
> 
> ...


I disagree with you because:

1. The contact patch width can only be as wide as the tread width, unless you are in the very bad position of riding on your sidewalls.

2. The most accepted theory on contact patch says that its area is proportional to the air pressure in the tire and the load on the tire. So for equal load on the tire, contact patch area is the same. Some argue it is wide and short vs narrow and long, but that is a different argument I have addressed in point 1. With that said, the force pushing back by the tire is the air pressure x the contact patch area. The only way this isn't true, is if the sidewall itself adds some structural support. I have been pondering this possibility, its usually assumed to be negligible.


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> It is true that the unloaded profile is more square. It is also true that raising the edge knobs would widen the contact patch, ONLY IF the tire pressure was high enough to prevent the flattening of the tire completely from edge to edge under a normal riding load. The whole idea of wider rims = wider contact patch came (I think) from the road tire world where pressures are very high and there are no knobs reaching for the ground. In that world, a flatter profile does widen the contact patch.
> 
> It is my thought that normal tire pressure in tubeless MTB tires these days, even on narrow rims, allows the tire to flatten across the total tread width, in which case a wider rim can do nothing to increase the contact patch width.
> 
> One final thought. As mentioned before, your argument for the benefit of wide rims comes from an advertisement for wide rims. Nothing against Derby. I have read a lot of his posts on this subject. Sometimes I agree, sometimes not, but regardless, he is selling wide rims.


He is selling wide rims that everyone is copying and that tire companies are now making tires for. Again the real benefit of these isn't the marginally bigger contact patch, tire width, air volumn, tread profile, etc. Most of these things are erased by running much less psi., that is if these changes even exist at all. The real benefit comes from getting away from a rim/tire profile that looks like a light bulb. This causes a wide, high volumn tire to be very flexible at the rim. A wider rim causes the rim/tire junction to be many times less flexible and stronger in at least 2 dimensions. Next is the psi drop. You can drop the psi a lot and still have a rim/tire junction that is less flexible, allowing more grip and still getting more rim protection.


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> The only way this isn't true, is if the sidewall itself adds some structural support. I have been pondering this possibility, its usually assumed to be negligible.


The sidewalls gain a lot of structural support with a wider rim, both laterally and vertically. And everywhere in between lateral and vertical.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> He is selling wide rims that everyone is copying and that tire companies are now making tires for.


I think you know as well as I do that people jumping on the band wagon of a new trend is not proof of anything.



> Again the real benefit of these isn't the marginally bigger contact patch, tire width, air volumn, tread profile, etc. Most of these things are erased by running much less psi., that is if these changes even exist at all.


Probably true.



> The real benefit comes from getting away from a rim/tire profile that looks like a light bulb. This causes a wide, high volumn tire to be very flexible at the rim. A wider rim causes the rim/tire junction to be many times less flexible and stronger in at least 2 dimensions. Next is the psi drop. You can drop the psi a lot and still have a rim/tire junction that is less flexible, allowing more grip and still getting more rim protection.


Cunningham says that they tested wide rims at low pressure and found them to burp or roll off the rim much less often. I think Cunningham has posted some "engineering" articles that are complete crap, but even if he is a crappy engineer, I don't think he's a liar, so I tend to believe his test results.

He tried to explain the reason for those results, and IMO, he failed. But, I think it has something to do with the sidewalls better resisting lateral forces, which is pretty much what you said. As I said before, I don't have an explanation for the "why", and that's what I'm looking for.

The whole lower pressure thing - I'm still skeptical. Even if the sidewalls have some cornering advantage with wider rims, I don't see any reason to think they offer any better rim protection from straight line strikes. (See my posts about contact patch area, tire height, and pressure.) So, the ability to corner better at lower pressure isn't much good if it increases the risk of rim strikes. And I think most tubeless riders are running pressures that are as low as practical from a rim protection standpoint.


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## smilinsteve (Jul 21, 2009)

Mountain Cycle Shawn said:


> The sidewalls gain a lot of structural support with a wider rim, both laterally and vertically. And everywhere in between lateral and vertical.


I get that that is a theory, but I haven't found any good explanation for it. Feel an unmounted tire sidewall and it is a flimsy piece of fabric that is easily squished between your fingers with barely an ounce of force. That is why it is usually assumed that your weight on the bike is supported by the air pressure in the tire, with no contribution from the side wall structure.


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> I think you know as well as I do that people jumping on the band wagon of a new trend is not proof of anything.
> 
> Probably true.
> 
> ...


They burp or roll off less because of the two humps on the inside of the rim that Ray designed and developed. That's one aspect that everyone is copying. They help a lot to hold the tire in against the hookless bead. The wider rim also helps, because of the decrease in the tire flex.

The increase rim strike protection is hard to explaine, I'll try. If the sidewall up and down has less of a light bulb shape and more of a perpendicular shape to the ground, any verticle force, like running straight over a curd, going up through the tire, goes through thicker layers of sidewall. Try this: curl your index finger to a C shape and press down on the tip of that finger with your other index finger. The finger you are pushing on flexes easily at the joint. Now straighten your index finger straight up and down and press down on the tip with your other index finger. It takes many times more force to get the finger you are pushing on to flex over. The same thing happens with a sidewall that has a light bulb shape. It will flex a lot easier. Stand the sidewall up and get rid of that bulg and it won't flex as easily. The wide rim stands the sidewall up and gives it more tension and strength.


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> I get that that is a theory, but I haven't found any good explanation for it. Feel an unmounted tire sidewall and it is a flimsy piece of fabric that is easily squished between your fingers with barely an ounce of force. That is why it is usually assumed that your weight on the bike is supported by the air pressure in the tire, with no contribution from the side wall structure.


No, the tire sidewall gives a lot of support along with psi. That's why some people complain about tires with thin sidewalls. Remember Umma Gumma tires. Very thin sidewalls that caused a lot of problems.


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> I get that that is a theory, but I haven't found any good explanation for it. Feel an unmounted tire sidewall and it is a flimsy piece of fabric that is easily squished between your fingers with barely an ounce of force. That is why it is usually assumed that your weight on the bike is supported by the air pressure in the tire, with no contribution from the side wall structure.


You're kinda right in a way. Put the sidewall in a bad position, like a narrow rim does and it has little support. Put in a better position with a wide rim, it now has many times more support. It gives it so much more support that you can lower psi and still have more support. It's really amazing how little changes can have such a big impact on how something works.


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## IPunchCholla (Dec 8, 2013)

Mountain Cycle Shawn said:


> You're kinda right in a way. Put the sidewall in a bad position, like a narrow rim does and it has little support. Put in a better position with a wide rim, it now has many times more support. It gives it so much more support that you can lower psi and still have more support. It's really amazing how little changes can have such a big impact on how something works.


Now don't get me wrong, I like wider rims, but this doesn't make sense to me. Wouldn't the amount of support a sidewall gives be independent of the air in the tire? In other words wouldn't the amount of support provided by the sidewall be the same if the tire was at normal atmospheric pressure (0 psi on a gauge) or inflated? So if wider rims allow for more sidewall support shouldn't that increase be apparent in totally flat tires?

When I got my new rims (granted they are only 25mm wide internal compared to my older 21mm internal) I could not tell a difference in support of inflated tires one to the next. Maybe it's there but if it is, it is so small that I think it plays an insignificant role.


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## eb1888 (Jan 27, 2012)

Maybe by visualizing the shape of the tire on two different width rims it can be easier to think about how a wider rim will allow the sidewall to help make the tire more difficult to wiggle side to side. More force would be needed the wider the tire beads were separated until you wouldn't be able to push the tire at the tread side to side at all. Whereas when the two beads are brought together and touch you can easily move it back and forth. That difference in washout threshold is significant when I'm riding.


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## Mountain Cycle Shawn (Jan 19, 2004)

IPunchCholla said:


> Now don't get me wrong, I like wider rims, but this doesn't make sense to me. Wouldn't the amount of support a sidewall gives be independent of the air in the tire? In other words wouldn't the amount of support provided by the sidewall be the same if the tire was at normal atmospheric pressure (0 psi on a gauge) or inflated? So if wider rims allow for more sidewall support shouldn't that increase be apparent in totally flat tires?
> 
> When I got my new rims (granted they are only 25mm wide internal compared to my older 21mm internal) I could not tell a difference in support of inflated tires one to the next. Maybe it's there but if it is, it is so small that I think it plays an insignificant role.


The air provides tension and support to the sidewall, it keeps it in a place so it can do its job. They depend on each other to work. I have a set of Spinergy wheels. The spokes are so flexible that you can tie them in a knot. But, build them in a wheel and tension the spokes and they are as strong as SS spokes.

You only made a 4 change in rim width. Try making a 15 or 20mm change. And it also depends on the tire or more importantly the ratio of rim width to tire width. Remember, you're just trying to get rid of the light bulb shape.


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## Mountain Cycle Shawn (Jan 19, 2004)

eb1888 said:


> Maybe by visualizing the shape of the tire on two different width rims it can be easier to think about how a wider rim will allow the sidewall to help make the tire more difficult to wiggle side to side. More force would be needed the wider the tire beads were separated until you wouldn't be able to push the tire at the tread side to side at all. Whereas when the two beads are brought together and touch you can easily move it back and forth. That difference in washout threshold is significant when I'm riding.


OMG, someone who understands this!


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## IPunchCholla (Dec 8, 2013)

Mountain Cycle Shawn said:


> The air provides tension and support to the sidewall, it keeps it in a place so it can do its job. They depend on each other to work. I have a set of Spinergy wheels. The spokes are so flexible that you can tie them in a knot. But, build them in a wheel and tension the spokes and they are as strong as SS spokes.
> 
> You only made a 4 change in rim width. Try making a 15 or 20mm change. And it also depends on the tire or more importantly the ratio of rim width to tire width. Remember, you're just trying to get rid of the light bulb shape.


Do you know if anybody who has actually tested this? I'm wondering because as soon as the tire has less on it the side wall will be somewhat S shaped regardless of rim width. I'm just having a hard time buying the rim strike benefits of wider rims.

now the anti-squirm, I totally buy. Even going to 25mm internal asked me to run significantly lower pressures without squirm. Plus the testing by specialized seems to confirm this, but I haven't seen anything from anyone actually experimenting on different rims and there effect on rim strikes?

There are plenty of people making the claim based on there experience, so clearly it is possible. I guess it just goes against my intuition and I tend to be a skeptic.


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## Mountain Cycle Shawn (Jan 19, 2004)

IPunchCholla said:


> Do you know if anybody who has actually tested this? I'm wondering because as soon as the tire has less on it the side wall will be somewhat S shaped regardless of rim width. I'm just having a hard time buying the rim strike benefits of wider rims.
> 
> now the anti-squirm, I totally buy. Even going to 25mm internal asked me to run significantly lower pressures without squirm. Plus the testing by specialized seems to confirm this, but I haven't seen anything from anyone actually experimenting on different rims and there effect on rim strikes?
> 
> There are plenty of people making the claim based on there experience, so clearly it is possible. I guess it just goes against my intuition and I tend to be a skeptic.


I get it, it's hard to understand and get it. But when you do its like a ligh bulb going off.

Another way I use to get this is: draw a verticle line of force up through the tire from the ground. If you draw it at the right spot, that line of force will enter the bottom of the tire, go into the tire and exit through the sidewall of the tire because the sidwall narrows down to meet the rim. When that line of force is not within the sidewall, the sidewall can't resist it. Now draw that line on the same spot with a wider rim. That line of force now goes through more of the sidewall at a less steep angle, because the sidewall has a more straight profile and it's not shaped like a light bulb anymore.

Here's another one for the lateral flex. I had the same tire on my Derby rim as I have on my 26mm Sinergy wheels. When you compare the two, my spinergy wheel and tire combo looks like a ligh bulb. When I look at my Derby wheel and tire setup it looks more like the profile of a car tire and wheels. When I take my hand and flex the Spinergy combo, I can flex the tire a lot. When I try the same thing with my Derby combo, the rear end of the bike flexes before the tire flexes side to side. It's many time stronger.

Also, it seems to me, that if a tire is stronger laterally for what ever reason, it will also be stronger vertically. I don't know how to explaine that though, except to say that a tire rolled over, will have less strength in the verticle direction, for the same reason the wider rim causes more strength vertically.


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## beanbag (Nov 20, 2005)

smilinsteve said:


> I disagree with you because:
> 
> 1. The contact patch width can only be as wide as the tread width, unless you are in the very bad position of riding on your sidewalls.
> 
> 2. The most accepted theory on contact patch says that its area is proportional to the air pressure in the tire and the load on the tire. So for equal load on the tire, contact patch area is the same. Some argue it is wide and short vs narrow and long, but that is a different argument I have addressed in point 1. With that said, the force pushing back by the tire is the air pressure x the contact patch area. The only way this isn't true, is if the sidewall itself adds some structural support. I have been pondering this possibility, its usually assumed to be negligible.


a) That is sorta true, except that in the case of a wider rim, the outer knobs push down harder, e.g. mazspeed's example.

b) This assumes that the pressure across the contact patch is uniform, which is only the case when the tire casing is very elastic. It's not elastic, so it's not uniform, so it invalidates your point 2. Secondly, in the case of a wider rim, irrespective of whether the tire casing is elastic or not, the wider rim allows putting down a bigger contact patch (or right before pinch flat, the side knobs push down harder) = more force.


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## Ridnparadise (Dec 14, 2007)

I have no idea what happens to the tread of a light-bulb tyre versus a D-shaped one in cornering, but I do know that rim strikes often happen after a tyre hits and displaces a rock (flips it up). If wide rims reduce this they are worth considering. Somehow the follow-on from that is whether straight edged tyres will get sidewall cuts more easily from rocks that do not displace.


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## paxfobiscum (Dec 16, 2014)

Whew! What a read....


One thing I am convinced about is that I need a new wheelset and I won't say what width. The question is... should I get DT 240 hubs or Project 321? LOL !


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## Mountain Cycle Shawn (Jan 19, 2004)

paxfobiscum said:


> Whew! What a read....
> 
> One thing I am convinced about is that I need a new wheelset and I won't say what width. The question is... should I get DT 240 hubs or Project 321? LOL !


I'd ride nothing buy Hadley hubs.


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## johnD (Mar 31, 2010)

paxfobiscum said:


> Whew! What a read....
> 
> One thing I am convinced about is that I need a new wheelset and I won't say what width. The question is... should I get DT 240 hubs or Project 321? LOL !


I like the dt swiss , you can rebuild one blindfolded.


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## turbodog (Feb 28, 2004)

J.B. Weld said:


> After 33 pages, thousands of wise words and sage advice, much careful consideration and deliberation, then weighing in all contributing factors I've concluded that for now I'm not believing the hype.


I agree. I'm about to rebuild a set of wheels with a modern alloy rim that's under 425g and 25mm internally. $65 each shipped. To use tubeless with a 26x2.3" tire. I'd say that's about as good of a compromise as you can get.


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## Trajan (Feb 9, 2004)

Mountain Cycle Shawn said:


> I just got back from a ride and I can't wipe the silly grin off my face. Lighter wheels, much more control and grip, wheels that look very cool. What more could I ask for from a set of wheels. Each ride gets better as I explore their limits. I'm pretty sure these wheels limits are much more than my limits are. And, just for the record, my WTB Mutano Raptors are only wider in the sidewall. The tread is not wider, but the edge knobs stand up about 3mm higher vertically, toward the top of the fork arch, but not out to the side.


Dude, those wheels look huge! 26? What pressures?


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## ColinL (Feb 9, 2012)

thankfully, Art's Cyclery has employed a mechanical engineer to settle this once and for all!

Tech: Why wider rims will improve your ride - Mtbr.com

So many flawed assumptions in that article. But my favorite is that since a wide rim makes a 2.25" tire better, there's no need to run a 2.4"! :lol:


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## Ridnparadise (Dec 14, 2007)

ColinL said:


> thankfully, Art's Cyclery has employed a mechanical engineer to settle this once and for all!
> 
> Tech: Why wider rims will improve your ride - Mtbr.com
> 
> So many flawed assumptions in that article. But my favorite is that since a wide rim makes a 2.25" tire better, there's no need to run a 2.4"! :lol:


Not only that, but to gain a benefit in rotational mass you have to use a thinner sidewall tyre, therefore undoing the benefits of reduced lateral deflection. Wider rims climb better because you can run 3lb less pressure and therefore have a wider contact patch - sounds like a wider tyre has the same effect? None of it was convincing. Not saying that wider rims aren't better, but it reads a bit like the enthusiasm for 29 wheels over 26 after all those years of whining about lack of stiffness. At least wide rims don't come with new "standards" that require more expensive parts like hubs and axels.


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## meltingfeather (May 3, 2007)

ColinL said:


> thankfully, Art's Cyclery has employed a mechanical engineer to settle this once and for all!
> 
> Tech: Why wider rims will improve your ride - Mtbr.com


This is a really interesting figure:









Description:


> The difference in width and how it affects this off-angle deflection is fully illustrated in the tests that Specialized conducted on their Roval Traverse Fattie wheels. Specialized switched a tire between a 22mm internal rim width and a 30mm "wide" wheel. The tire and wheel were then loaded on an angle and the deflection was measured over a range of different loads. The test bench and deflection measurements can be seen below. Results show that at 900 newtons of loading, the narrower, less supportive rim allows for 50mm of tire deflection, while the wider rim supports the tire more, only allowing for around 33mm of deflection.


*Really* interesting... I'm going to think about it some more before wholesale discounting the article based on what I already thought.



ColinL said:


> So many flawed assumptions in that article. But my favorite is that since a wide rim makes a 2.25" tire better, there's no need to run a 2.4"! :lol:


The article didn't say that.


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## ColinL (Feb 9, 2012)

meltingfeather said:


> The article didn't say that.


I paraphrased, but it most definitely claimed a weight savings by using a 2.25" tire on a wide rim, compared to a 2.4" on a narrower rim. It's there.


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## meltingfeather (May 3, 2007)

ColinL said:


> I *editorialized*


FIFY
there's a difference

Here's what the article actually said:


> Although performance characteristics are not directly comparable with added rim width and added tire width, we can loosely compare this 26-gram increase due to rim width to the 202-gram increase in tire weight when moving from a Geax Goma 2.25 to a 2.4. The point being: It will save a lot of weight to add air volume and contact area by increasing the rim width instead of tire width.


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## ColinL (Feb 9, 2012)

meltingfeather said:


> FIFY
> there's a difference
> 
> Here's what the article actually said:


the whole article is an editorial!

or did I miss the part where he did some double blind testing and found that not only were the wide rims faster, but also people subjectively preferred them?


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## smilinsteve (Jul 21, 2009)

I like how he summarizes at the end...



> Bottom line: It's my *very educated* opinion that...


:lol:


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## Mountain Cycle Shawn (Jan 19, 2004)

Trajan said:


> Dude, those wheels look huge! 26? What pressures?


Sorry, I didn't see this till the thread blew up today. Yes, 26" rims and that picture was taken, I believe, with 22psi. Tires are WTB Mutano Race 2.4".


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## pharmaboy (Nov 11, 2005)

meltingfeather said:


> This is a really interesting figure:
> 
> 
> 
> ...


That piccy from specialized is what I understood to be the driving argument for less burping - the reasonable proof so to speak as I assume deflection is indeed what causes burping.

Note the assumption of the 10% increase in volume and what that means - and also given the access to the wheels,didn't bother to actually test the volume change witha simple submersion test.

The other simple test they could do, is the require force to cause a rim strike on a square angle at the same pressure. Jeez, I could probably devise a test to do it with 2 wheels a tyre pressure guage, a tie down strap and a luggage scale

Why doesn't someone just do the bloody simple tests that are required rather than make all these assumptions


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## Mountain Cycle Shawn (Jan 19, 2004)

Riding is all the testing I need. And, I still can't get the silly grin off my face. Wide rims are here to stay!


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## pharmaboy (Nov 11, 2005)

smilinsteve said:


> I like how he summarizes at the end...
> 
> :lol:


Oh the hubris! 

Find me a man that's certain of his opinion and I give you a fool.

One of those things, the more you actually know about a subject, the more doubt you realise there is


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## manitou2200 (Apr 28, 2006)

^^ You amaze me dude, really!! It's not that I don't agree with you an the quality of performance of a wider rim (and tire), I do agree! I like my wider rimmed wheels!! I've riding 26 x 30 mm ID rims since 2006 on my big bikes and I have 29 x30 ID Fatties as well as 29+ Dually rimmed wheels. 

All this banter from you on wide rims and the light bulb analogy and you're just getting into a set of wide Derby's now? 

I had to leave this thread for a few weeks because the BS was way deep, that and the snow was also deep in CA and it needed to get skied! I stopped back in here tonight for more amusement which it provided! It literally has been a broken record for months and months. There are those who believe in the wide rims and those who don't and they've gathered here to debate and battle it out. 

Not to pick on you dude but seriously 9400 post on mtbr? Do you live here? Do you ever get off of this forum and actually ride? Sorry but looking at your photos last page of your bike build I'd say probably not much (but I do like your wheels and tires!)! I don't spend much time on this forum or any for that matter because I ride and ski and paddle and climb!!! "Less typing more riding" to quote Kelly McGarry! haha. I can see why oldranger is disgusted with this thread he started, it's gone over the edge and rambling on into the grave! I say wide wheels are definitely not going away, so long live wide wheels! I'm not going to be running wide wheels on my road bike but I do like my [email protected] 100 psi which is kinda wide for road bike tire! Have fun! Over and out, I'm outta here......again!!


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## turbodog (Feb 28, 2004)

Engineer? Right. Way too much marketing BS in that article.


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## turbodog (Feb 28, 2004)

EX471's at 25mm internal width are still very popular for WC downhill.....and win. End of story.

2015 Specialized S-Works Demo DH Bike | UCI World Cup


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> ^^ You amaze me dude, really!! It's not that I don't agree with you an the quality of performance of a wider rim (and tire), I do agree! I like my wider rimmed wheels!! I've riding 26 x 30 mm ID rims since 2006 on my big bikes and I have 29 x30 ID Fatties as well as 29+ Dually rimmed wheels.
> 
> All this banter from you on wide rims and the light bulb analogy and you're just getting into a set of wide Derby's now?
> 
> ...


Wow, someone is suffering from serious panty bindage! I've been here a long time. I have a whopping 2.3 posts per day. That takes like ten minutes of my time. And, since I don't have to work much it leaves me plenty of time to ride. Especially when the trails are on my property. Have a nice day!


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## Mountain Cycle Shawn (Jan 19, 2004)

manitou2200 said:


> All this banter from you on wide rims and the light bulb analogy and you're just getting into a set of wide Derby's now?


Just so you know, and I think I posted somewhere, I've been on a set of borrowed Derbys for about three months before I bought mine. So no, I'm not, "just getting into a set of wide Derbys".


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## meltingfeather (May 3, 2007)

pharmaboy said:


> Note the assumption of the 10% increase in volume and what that means - and also given the access to the wheels,didn't bother to actually test the volume change witha simple submersion test.


I don't see anything in the article that says the 10% is an assumption. In fact it says, "almost 10%," which suggests to me that there is an actual number and that it is slightly lower than 10%.
I agree that the article is not great, but hypocritical critiques editorializing the content and claiming it says things that it doesn't aren't any better.
If the article is so full of holes it shouldn't have to be misquoted to make your point.


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## Mountain Cycle Shawn (Jan 19, 2004)

Even CX is going wide:
Zipp spins up new 30 Course disc brake wheels


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## zephxiii (Aug 12, 2011)

So... I've been running Arch Ex which is 21mm inner with 2.0-2.2 tires. 

I've been thinking about LB 24mm inner width rims but kinda wondering if that is not enough difference? 

With the Arch EX I've never had a burp, but squirm is an issue sometimes so it would be nice to get rid of that. 

I don't want to be heavier than Arch Ex but I do wanna be stiffer, but I'm kinda at a spot of confusion on whether the 24mm or 30mm inner width for someone that wants to run 2.2 xc tires. 

I kinda wish their 24mm rims were more 25 or 26...

Sent from my SAMSUNG-SGH-I337 using Tapatalk


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## cycloxer13 (Oct 27, 2014)

Wide is better, imo, and it is just my opinion. I am running 30mm Nextie carbons (25mm internal) with Bontrager XR3 2.3's at 17 and 19 psi. They work exceptionally well.


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## slowride454 (Jan 11, 2014)

I am going to take on this burning debate, and do a little experiment. I know how my Carve rides with Continental 2.4 Trail Kings on P35s. I am rebuilding my CX bike and could try those wheels. they are H Plus Son 42 deep section rims. Maybe deeper is better than wider. I can start a hipster, tight pant revolution in DH racing. Anyone want to make suggestions for test parameters?


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## ban (Jul 24, 2004)

Easton joins to the party First Look: Easton's Wide ARC Rims - Pinkbike


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## ColinL (Feb 9, 2012)

quote: ''Rim width should match tire volume. If you are running a large volume tire, a 30mm internal rim width provides an optimal tire profile,'' Easton says. Not looking to run the big meat? ''For lower volume cross-country and trail tires, 24 and 27mm internal rim widths provide the ideal balance between tire shape and wheel weight.'' 

so, on wide rims, it's probably an excellent idea to run monster truck tires like those 26x2.4" Mutano Race shown a few pages back...


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## Mountain Cycle Shawn (Jan 19, 2004)

ColinL said:


> quote: ''Rim width should match tire volume. If you are running a large volume tire, a 30mm internal rim width provides an optimal tire profile,'' Easton says. Not looking to run the big meat? ''For lower volume cross-country and trail tires, 24 and 27mm internal rim widths provide the ideal balance between tire shape and wheel weight.''
> 
> so, on wide rims, it's probably an excellent idea to run monster truck tires like those 26x2.4" Mutano Race shown a few pages back...


They aren't all that wide. They measure 55mm across, but weight about 590 grams per tire. About the same size as my Trail King 2.4.


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## smilinsteve (Jul 21, 2009)

Just a thought:
These companies like Easton and American Classic are suddenly explaining the "science" of wide rim benefits, but they've been making rims for decades, and wide rims have always been an option. So, are they saying they didn't know how to design rims all these years? They screwed up by not knowing these now obvious scientific facts? Or are they just jumping on a marketing opportunity?


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## Mountain Cycle Shawn (Jan 19, 2004)

smilinsteve said:


> Just a thought:
> These companies like Easton and American Classic are suddenly explaining the "science" of wide rim benefits, but they've been making rims for decades, and wide rims have always been an option. So, are they saying they didn't know how to design rims all these years? They screwed up by not knowing these now obvious scientific facts? Or are they just jumping on a marketing opportunity?


No, carbon is now accepted as a material for rims. Rims this wide are to heavy in aluminum. It was tried, but no one wanted them. Carbon allows light wide rims.


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## ColinL (Feb 9, 2012)

Mountain Cycle Shawn said:


> They aren't all that wide. They measure 55mm across, but weight about 590 grams per tire. About the same size as my Trail King 2.4.


They looked absolutely massive, unless you photoshopped that pic. 

But I think Easton's point, and one that we've heard before from other manufacturers, is that there is a relationship between rim and tire width.


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## Zowie (Aug 3, 2013)

Mountain Cycle Shawn said:


> Rims this wide are to heavy in aluminum. It was tried, but no one wanted them.


Surly, Sun, and Kris Holm made rims that no one wanted?

Wonder why they're still making them.


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## Le Duke (Mar 23, 2009)

Zowie said:


> Surly, Sun, and Kris Holm made rims that no one wanted?
> 
> Wonder why they're still making them.


Too heavy for the vast majority of consumers to fork out the money they were selling them for? Yes.


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> No, carbon is now accepted as a material for rims. Rims this wide are to heavy in aluminum. It was tried, but no one wanted them. Carbon allows light wide rims.





ColinL said:


> They looked absolutely massive, unless you photoshopped that pic.
> 
> But I think Easton's point, and one that we've heard before from other manufacturers, is that there is a relationship between rim and tire width.





Zowie said:


> Surly, Sun, and Kris Holm made rims that no one wanted?
> 
> Wonder why they're still making them.


You guys all make valid points here but besides the carbon manufacturing advancements, the fat bike movement has also made wide rims valid. It's really just getting started with the development of wide wheels chasing tires chasing wheels. 
It should be fun!


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## turbodog (Feb 28, 2004)

Fat rims have been around for a while, they were heavy though.










Doublewides were 33mm internal with a 900g-1000g weight in 26". Mavic has made the EX729 for many years too, 675g. 3" nokian gazzaloddi's on doublewides was pretty awesome to ride down a hill, and boat anchor heavy.

I've seen both these rims with massive dents in them, while running two ply DH tires and thick tubes. Be careful with any of these light wide rims running wimpy tires tubeless with low pressure, any hard riding is going to result in dents. Makes excessive width sort of a moot point - you may have less tire roll, but you still need enough air pressure to prevent rim dents and sidewall cuts. If you ride agressively, the higher pressure you need to keep from bottoming out the tire is also going to keep the tire from rolling off. This is part of why you aren't seeing DH on 30mm+ internal rims.

Only sub 500g rim I would trust for hard riding is the dt EX471, at 25mm internal. I'm putting WTB KOM i25's on my bike, but I run maxxis with higher pressures and don't ride that agressively these days.


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## turbodog (Feb 28, 2004)

ban said:


> Easton joins to the party First Look: Easton's Wide ARC Rims - Pinkbike


75% of the comments are asking "why no 26?" Thankfully, there are plenty of modern semi-wide 26" rims.


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## AndrewBikeGuide (Nov 12, 2014)

ColinL said:


> I think we can all agree that bicycle tires are supported by air pressure, and that the tire carcass itself does not offer any meaningful support. Isn't that evident by handling any unmounted tire, or by observing a bicycle at rest on a flat tire? The specific pressure required is determined by the tire, certainly - but the manufacturer has thoughtfully printed this on the side of the tire.
> 
> Consider this in contrast to run-flat car tires, which are specifically built to have a really tough sidewall and tire carcass that can support the weight of the car temporarily with low / no air pressure. You can't do that with a mountain bike tire.


It appears that you have never met a Michelin Comp 16 DH 2.4"! No added air and very little deformation when on a 35lb bike. A truely stiff sidewall and a total gorilla wrestle to get onto a Mavic 823. One could quite safely run 18-22 psi for downhill speeds on technical and rocky course (Dragon series/ UK NPS) without dinging rims and without burping the tyre from the rim.
The original, and still some ways unmatched, true UST DH tyre.


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## meltingfeather (May 3, 2007)

AndrewBikeGuide said:


> One could quite safely run 18-22 psi for downhill speeds on technical and rocky course (Dragon series/ UK NPS) without dinging rims and without burping the tyre from the rim.


Not if you're as big a bad ass as oldranger claims to be. :arf:


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## zephxiii (Aug 12, 2011)

I can definitely feel the difference in sidewall between my Maxxis Minion DHF and thinner XC tires. 

Sent from my SAMSUNG-SGH-I337 using Tapatalk


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## Zowie (Aug 3, 2013)

Le Duke said:


> Too heavy for the vast majority of consumers to fork out the money they were selling them for? Yes.


The vast majority of people will never get a rim strung up... :lol:


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## ColinL (Feb 9, 2012)

zephxiii said:


> I can definitely feel the difference in sidewall between my Maxxis Minion DHF and thinner XC tires.


Yes, but with no air in it, they both will sag until they're resting on the rim. Guaranteed.



AndrewBikeGuide said:


> It appears that you have never met a Michelin Comp 16 DH 2.4"! No added air and very little deformation when on a 35lb bike. A truely stiff sidewall and a total gorilla wrestle to get onto a Mavic 823. One could quite safely run 18-22 psi for downhill speeds on technical and rocky course (Dragon series/ UK NPS) without dinging rims and without burping the tyre from the rim.
> The original, and still some ways unmatched, true UST DH tyre.


Ok, so we have one tire and perhaps you can find some other examples. They are rarities, exceptions to the rule, and probably not even in production today.

But I believe somewhere in this mess of a thread, bholwell confirmed that MTB tires do not get significant support from the tire carcass itself; it's supported by air.


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## smilinsteve (Jul 21, 2009)

ColinL said:


> Yes, but with no air in it, they both will sag until they're resting on the rim. Guaranteed.
> 
> Ok, so we have one tire and perhaps you can find some other examples. They are rarities, exceptions to the rule, and probably not even in production today.
> 
> But I believe somewhere in this mess of a thread, bholwell confirmed that MTB tires do not get significant support from the tire carcass itself; it's supported by air.


I think the simple idea that weight on tire = tire pressure x contact patch area is not exactly true. The same general assumption is made for car tires and this study found very wacky behavior contrary to the assumption (including contact patch decreasing when pressure decreased in a few examples!)

Fact or fiction? Tire contact patch size is determined mostly by weight and tire pressure. | Performance Simulations

I'm not claiming to understand it, but just because a tire sidewall is flimsy and offers no support by itself, does not mean that it offers no support when there is pressure on it. For the same reason, I think using a tube in a tire changes the feel of its compliance even though an uninflated tube has no stiffness to explain this feeling.

And people with wide rims claim to feel a difference, just as people running tubeless claim to feel a difference. If air pressure was the sole variable, those differences would not exist. (I admit that people feel what they want to feel many times, but there seems to be enough consensus to give some credence to the idea).


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## meltingfeather (May 3, 2007)

smilinsteve said:


> I think the simple idea that weight on tire = tire pressure x contact patch area is not exactly true. The same general assumption is made for car tires and this study found very wacky behavior contrary to the assumption (including contact patch decreasing when pressure decreased in a few examples!)
> 
> Fact or fiction? Tire contact patch size is determined mostly by weight and tire pressure. | Performance Simulations


I think belted radials are a radically different application and there are significant limitations to that "study," which took data collected for another purpose and calculated contact patch based on a crude assumption... pretty weak basis for groundbreaking "findings" IMO.



smilinsteve said:


> I'm not claiming to understand it, but just because a tire sidewall is flimsy and offers no support by itself, does not mean that it offers no support when there is pressure on it. For the same reason, I think using a tube in a tire changes the *feel *of its compliance even though an uninflated tube has no stiffness to explain this feeling.
> 
> And people with wide rims claim to *feel *a difference, just as people running tubeless claim to feel a difference. If air pressure was the sole variable, t*hose differences* would not exist. (I admit that people feel what they want to feel many times, but there seems to be enough consensus to give some credence to the idea).


Feel is *meaningless* when it comes to physical and mechanical properties of tires.


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## tigris99 (Aug 26, 2012)

Omg this has gotten interesting.

Feel is meaningless when it comes to properties of tires....the design of a tire affects how the tire reacts under use, thus can feel different because it responds differently. Tread design, compound, sidewall design can all have an effect. How a mtb tire feels matters to a rider because everything about a mountain bike is about feel.


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## zephxiii (Aug 12, 2011)

Yeah I was gonna say, how it feels is everything in mountain biking lol. 

Sent from my SAMSUNG-SGH-I337 using Tapatalk


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## meltingfeather (May 3, 2007)

zephxiii said:


> Yeah I was gonna say, how it feels is everything in mountain biking lol.
> 
> Sent from my SAMSUNG-SGH-I337 using Tapatalk


I should add to what I said that feel is everything for determining what you should or want to ride. There's a breakdown between that and what people want to quibble about on the Internet, which is tying feel and preference to some quantifiable physical basis to argue about.


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## pharmaboy (Nov 11, 2005)

tigris99 said:


> Omg this has gotten interesting.
> 
> Feel is meaningless when it comes to properties of tires....the design of a tire affects how the tire reacts under use, thus can feel different because it responds differently. Tread design, compound, sidewall design can all have an effect. How a mtb tire feels matters to a rider because everything about a mountain bike is about feel.


I'm thinking that melting feather was saying, if you can feel it you can measure it, if you can't measure it you don't know what you are feeling or if it's real.

Love those pictures of the double wide - I had a pair of the rhino lite wides as well fitted with trailbear tyres from memory - there was no hype at the time that they were going to take over the world. Good rims though


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## Mountain Cycle Shawn (Jan 19, 2004)

Mine feel bittchen!!


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## ban (Jul 24, 2004)

is anyone running High Rollers II 2.4 27.5 with wide rims? how is the clearence of the chain stays? I'm running 2.3 right now but maybe I'd try a little wider tire.....


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## Le Duke (Mar 23, 2009)

slowride454 said:


> I am going to take on this burning debate, and do a little experiment. I know how my Carve rides with Continental 2.4 Trail Kings on P35s. I am rebuilding my CX bike and could try those wheels. they are H Plus Son 42 deep section rims. Maybe deeper is better than wider. I can start a hipster, tight pant revolution in DH racing. Anyone want to make suggestions for test parameters?


I am genuinely confused as to what you are trying to say here.


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## bholwell (Oct 17, 2007)

ban said:


> is anyone running High Rollers II 2.4 27.5 with wide rims? how is the clearence of the chain stays? I'm running 2.3 right now but maybe I'd try a little wider tire.....


The casing width should be roughly the same, and the tread width should be a couple mm greater.


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## Mountain Cycle Shawn (Jan 19, 2004)

Le Duke said:


> I am genuinely confused as to what you are trying to say here.


I think he went a little to tight on the pants.


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## manitou2200 (Apr 28, 2006)

Mountain Cycle Shawn said:


> I think he went a little to tight on the pants.


LOL....LMFAO! This thread needs more humor.


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## slowride454 (Jan 11, 2014)

Le Duke said:


> I am genuinely confused as to what you are trying to say here.


these rims with a 2.4 or even a 3.0 mounted on my Carve. I know how it handles with P35s and the TK 2.4 I just picked up one Chupacabra to try also. The tight pant reference was to the fixie style deep dish wheels.


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## ban (Jul 24, 2004)

bholwell said:


> The casing width should be roughly the same, and the tread width should be a couple mm greater.


Ok cheers for the info


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## meltingfeather (May 3, 2007)

meltingfeather said:


> I should add to what I said that feel is everything for determining what you should or want to ride. There's a breakdown between that and what people want to quibble about on the Internet, which is tying feel and preference to some quantifiable physical basis to argue about.


definitely worth a chicken sh|t neg rep... thanks LyNx!  :thumbsup:


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## eb1888 (Jan 27, 2012)

Here's a thread with good on trail reviews of wide rims with a wider 27+ WTB Trail Blazer. These guys are really having fun.
http://forums.mtbr.com/29er-bikes/27-5-wheels-tires-kona-process-111-a-946050.html


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## eb1888 (Jan 27, 2012)

More good options from Schwalbe in 27.5+ tires 2.8 and 3" wide. They recommend a minimum 40mm inside dimension wheel.
Sea Otter 2015 | Schwalbe presents Plus-Size Rocket Ron & Nobby Nic | ENDURO Mountainbike Magazine









Rocket Ron


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## slowride454 (Jan 11, 2014)

what a bunch of BS. They will work just fine on 19mm external rims. Its a conspiracy! All these new standards. This season I had to get new wheels because the fork I got had 15x100TA.


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## Mountain Cycle Shawn (Jan 19, 2004)

slowride454 said:


> what a bunch of BS. They will work just fine on 19mm external rims. Its a conspiracy! All these new standards. This season I had to get new wheels because the fork I got had 15x100TA.


Until they flex right off the rim.

And, no one forced you to buy a fork that required new wheels.


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## slowride454 (Jan 11, 2014)

Mountain Cycle Shawn said:


> Until they flex right off the rim.
> 
> And, no one forced you to buy a fork that required new wheels.


yes they did. and don't even get me started on the tapered steerer which necessitated a new lower bearing and cup. You can't get a decent 29er fork anymore with a QR. anyway, we can all enjoy our new 15x110TA and additional rear axle standards along with wide rims.


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## Mountain Cycle Shawn (Jan 19, 2004)

slowride454 said:


> yes they did. and don't even get me started on the tapered steerer which necessitated a new lower bearing and cup. You can't get a decent 29er fork anymore with a QR. anyway, we can all enjoy our new 15x110TA and additional rear axle standards along with wide rims.


Makin' your ride better is what it's all about!


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## slowride454 (Jan 11, 2014)

it's this thread for the luddites??? don't believe the hype right? Just trying to fit in.


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## tigris99 (Aug 26, 2012)

slowride454 said:


> yes they did. and don't even get me started on the tapered steerer which necessitated a new lower bearing and cup. You can't get a decent 29er fork anymore with a QR. anyway, we can all enjoy our new 15x110TA and additional rear axle standards along with wide rims.


I got a "decent fork" with qr no problem. Joys of placing my fork faith in Manitou 

Loving my 25mm id rims with 2.35/2.2 tires. I'm actually looking forward to building a b+ when I can afford to get a new bike (like my 29er is that old). Wider tires and wider rims means I can avoid buying FS longer. Like ht but body may not for too many more years.


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## smilinsteve (Jul 21, 2009)

If a 2.8 tire needs a 40mm rim, a 2.3 must need a 35mm?


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## tigris99 (Aug 26, 2012)

smilinsteve said:


> If a 2.8 tire needs a 40mm rim, a 2.3 must need a 35mm?


1/2 difference in tire, 13mm, so not sure where you came up with 35mm.


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## smilinsteve (Jul 21, 2009)

tigris99 said:


> 1/2 difference in tire, 13mm, so not sure where you came up with 35mm.


2.3 is 18% smaller Than 2.8. 33 is 18% less than 40. But I was estimating of the top of my head. ..


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## eb1888 (Jan 27, 2012)

It's not just the raw width. The tread pattern and casing profile design contribute to what the manufacturer recommends. 
These seem to be designed specifically for a 40mm inside rim to perform at their maximum according to Schwalbe. 
They do testing and development to come up with that, I'm sure.


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## Dictatorsaurus (Sep 11, 2009)

I thought I'd share some information.

My Ikon 2.2 width on 20mm rim is 53mm. The Ikon width on a 23mm rim is 56mm.

Exactly 3mm difference which is about 5%.

Very minor difference.


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## paxfobiscum (Dec 16, 2014)

Mountain Cycle Shawn said:


> I just got back from a ride and I can't wipe the silly grin off my face. Lighter wheels, much more control and grip, wheels that look very cool. What more could I ask for from a set of wheels. Each ride gets better as I explore their limits. I'm pretty sure these wheels limits are much more than my limits are. And, just for the record, my WTB Mutano Raptors are only wider in the sidewall. The tread is not wider, but the edge knobs stand up about 3mm higher vertically, toward the top of the fork arch, but not out to the side.


Now that is one good looking bike. Are those 27+ wheels? What are the specs? What tires are those? Sweet!
.


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## Mountain Cycle Shawn (Jan 19, 2004)

paxfobiscum said:


> Now that is one good looking bike. Are those 27+ wheels? What are the specs? What tires are those? Sweet!
> .


Thanks! WTB Mutano Raptor Race in 26 x 2.4. Some of the best tires made, if you can ride on very light tires. But, they are getting very hard to find.

Were you asking for bike specs?


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## Mountain Cycle Shawn (Jan 19, 2004)

Dictatorsaurus said:


> I thought I'd share some information.
> 
> My Ikon 2.2 width on 20mm rim is 53mm. The Ikon width on a 23mm rim is 56mm.
> 
> ...


Sidewall or tread?


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## AndrewBikeGuide (Nov 12, 2014)

slowride454 said:


> yes they did. and don't even get me started on the tapered steerer which necessitated a new lower bearing and cup. You can't get a decent 29er fork anymore with a QR. anyway, we can all enjoy our new 15x110TA and additional rear axle standards along with wide rims.


There has never ever been such a thing as a "decent 29er fork.....with a QR". Even when ridding with a bare minimum of kit I cannot see how adding a 5 or 6mm allen key to a patch/ tube kit makes any significant difference to a minimum load ride (cell phone, $20 note, energy bar, minitool, Co2, tube and a water bottle).

I think that through axles are genius. And wide rims (24-29 inner) are a great addition to running tubeless (assuming 2.4" or larger tyres).
Not sure why we cannot just have 157mm on trail bikes as well as DH bikes but perhaps the 83mm axle is not ideal for pedalling Q factor?


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## TheUnknownRider (Oct 2, 2015)

Going back to the original premise of this thread, what people win on varies greatly by a wide variety of factors , but the #1 factor is their talent, not their equipment. The guys on top can swap out their factory equipment with the avg. enthusiast and still leave them looking like a drunk derelict that never rode on two wheels before. They may have never even tried wide wheels, or the right wide wheels, before and just went off what they believed to be a logical assumption that wider is heavier is slower. Sometimes other factors weigh in that weren't properly accounted for. People assume their mental deduction is logical, but it doesn't always pan out that way. The only way to know for sure is to actually try it. Even then, what was true today is not necessarily true tomorrow. People often get too caught up in generalities as truth for life, place too much emphasis on pointless theoretical minutia, etc. and slowly become victims of their own closed-mindedness. 

I've seen it happen across countless activities, biking is no different in that regard.


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## pharmaboy (Nov 11, 2005)

Trying something out is no way to make a judgement. That's how people come to the view that homeopathy works. If you are having a good day, you will be faster, if a bad day, then slower - if you were trying out a different brand of stem the same length, you wouldn't conclude that your new found prowess is from the change in stem, but if it's something you Believe in, you will.

That is why your point about logic is true - people can't test in a non blinded situation and make accurate comparisons.

On pros - in most sports, professionals are at the pointy end of product development - they test the latest and greatest and reject or use based on that. This is the reason that so many are deeply suspicious of this particular "technology", because it's coming from the product marketers first into the average Joe market and very slowly permeating into sponsored professional ranks.


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## Mountain Cycle Shawn (Jan 19, 2004)

TheUnknownRider said:


> Going back to the original premise of this thread, what people win on varies greatly by a wide variety of factors , but the #1 factor is their talent, not their equipment. The guys on top can swap out their factory equipment with the avg. enthusiast and still leave them looking like a drunk derelict that never rode on two wheels before. They may have never even tried wide wheels, or the right wide wheels, before and just went off what they believed to be a logical assumption that wider is heavier is slower. Sometimes other factors weigh in that weren't properly accounted for. People assume their mental deduction is logical, but it doesn't always pan out that way. The only way to know for sure is to actually try it. Even then, what was true today is not necessarily true tomorrow. People often get too caught up in generalities as truth for life, place too much emphasis on pointless theoretical minutia, etc. and slowly become victims of their own closed-mindedness.
> 
> I've seen it happen across countless activities, biking is no different in that regard.


This is pure BS. Competition is so stiff, you better be at the top of your game mentally, physically and have the best equipment possible if you want to be a winner at the top.


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## TheUnknownRider (Oct 2, 2015)

Mountain Cycle Shawn said:


> This is pure BS. Competition is so stiff, you better be at the top of your game mentally, physically and have the best equipment possible if you want to be a winner at the top.


well I'm sure there's no convincing someone with such an absolute viewpoint so I won't quibble past this reply, but I've been around a lot of wheeled sports in my life and there are always that rare few who have some kind of magical talent over everyone else. The best equipment doesn't always win, not that anyone with advertising potential will ever admit to such a thing. However, if you go back and reread what I wrote, my comparison is not the same as your counter-comparison. Some people have an innate gift that makes them capable of winning even when the odds are against them.

It doesn't mean that they don't get beat. Luck plays into it as much as anything you listed above, again another point that nobody in that position ever wants to concede to. It also doesn't take away from the other points I was trying to make. Generally speaking, racing in every form is one of the most monkey-see, monkey-do games around. Just because they are all in there hanging with each other doesn't mean they aren't all overlooking something that nobody has caught onto yet. Nobody in that position *ever* wants to believe that such a thing is possible. At least not until somebody comes long and shakes the tree ...


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## keen (Jan 13, 2004)

pharmaboy said:


> Trying something out is no way to make a judgement. That's how people come to the view that homeopathy works. If you are having a good day, you will be faster, if a bad day, then slower - if you were trying out a different brand of stem the same length, you wouldn't conclude that your new found prowess is from the change in stem, but if it's something you Believe in, you will.
> 
> That is why your point about logic is true - people can't test in a non blinded situation and make accurate comparisons.
> 
> On pros - in most sports, professionals are at the pointy end of product development - they test the latest and greatest and reject or use based on that. This is the reason that so many are deeply suspicious of this particular "technology", because it's coming from the product marketers first into the average Joe market and very slowly permeating into sponsored professional ranks.


After I spend a lot of $$ on the latest and greatest I really try to convince myself my money was well spent. Sometimes its hard to discern if the bike feels faster, smoother or whatever I dropped coin on. I will say I can tell usually after my internal super sensitivity drops. I could be riding along the same trail I have ridden 100 times and say this recent tire set does feel different. Anyways I went from 22mm ID rims to 30mm ID rims and there is a difference. Doesn't really matter, for others, how it changed for my terrain or riding style other than it works for me.


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## cycloxer13 (Oct 27, 2014)

Wider rims are better. I used to race pro XC. I am a mechanical engineer by trade. Take it for what you will. It's just my opinion. I also own a fat bike with 4.6" tires on 90 mmm rims. That is fine for snow, but too wide for dirt. My Evil is running 30mm rims and 2.4 Maxxis tires. I consider it the bare minimum these days. Again, just my subjective opinion.


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## pharmaboy (Nov 11, 2005)

keen said:


> After I spend a lot of $$ on the latest and greatest I really try to convince myself my money was well spent. Sometimes its hard to discern if the bike feels faster, smoother or whatever I dropped coin on. I will say I can tell usually after my internal super sensitivity drops. I could be riding along the same trail I have ridden 100 times and say this recent tire set does feel different. Anyways I went from 22mm ID rims to 30mm ID rims and there is a difference. Doesn't really matter, for others, how it changed for my terrain or riding style other than it works for me.


I think one thing that does make a difference for mere mortals like me, is confidence.

No doubt, when I feel the flow, and am confident I can ride much faster, I can let the front wheel slip a little on every corner - but most of the time I let my mind think about what might happen. So if what you bought makes you feel faster, you are faster


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## cycloxer13 (Oct 27, 2014)

pharmaboy said:


> I think one thing that does make a difference for mere mortals like me, is confidence.


You get a bigger contact patch. As tires improve to take advantage of the width, it'll all get even better.

I'm on 30's now. My next wheels will be 35 or 40. You couldn't pry them out of my hands and make me ride narrow rims again.


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## Le Duke (Mar 23, 2009)

cycloxer13 said:


> You get a bigger contact patch. As tires improve to take advantage of the width, it'll all get even better.
> 
> I'm on 30's now. My next wheels will be 35 or 40. You couldn't pry them out of my hands and make me ride narrow rims again.


You don't get a bigger contact patch unless you reduce pressure.

Patch area is a function of weight and pressure. That's it. Shape? That's a different story.

However, in theory, a wider rim might help with allowing slightly reduced pressures, due to additional tire support.

Sent from my XT1585 using Tapatalk


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## Dictatorsaurus (Sep 11, 2009)

My Ikon 2.2 width on a 20mm rim was 53mm and on a 23mm rim 56mm. A mere 5% increase. 

I had the option of going Easton Arc27 or 30 for my AM WFO9 build. I opted for the 27 rims.

All this "bigger and wider is better" contradicts the obsessions with going light culture from a few years back. Fat bikes, Plus bikes, wide rims are all nice to have as options. But to claim "better" is very subjective.

I see it all the time. Fat bikes are selling like hot cakes and I see them every time I'm out. The owners love them and claim they are fun but I also see them struggle pushing and rolling all that weight around.


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## Suns_PSD (Dec 13, 2013)

I've only been mountain biking for about 2 years, and I've only been to a bike park once. But I do really enjoy and I do it at a fairly high level. For an amateur. At the bike park we had skinny narrow hard tires which worked great for skipping over rocks at high speed. The traction kind of sucked but it didn't really seem to matter in that application. For trail riding however the speeds are slower than there's lots more climbing and off camber obstacles, and I've had good luck with wider wheels and tires so far. I do feel that some of the widths that are being suggested are blatantly too wide, but I don't have a bunch of experience on different widths and different tires.


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## cycloxer13 (Oct 27, 2014)

I'm running lower pressure. 16.5 front, 19 rear, +/- depending on the conditions


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## Le Duke (Mar 23, 2009)

Dictatorsaurus said:


> My Ikon 2.2 width on a 20mm rim was 53mm and on a 23mm rim 56mm. A mere 5% increase.
> 
> I had the option of going Easton Arc27 or 30 for my AM WFO9 build. I opted for the 27 rims.
> 
> ...


Why not have both?

Wide/big + light?

My ASRc could be under 21lbs with semi-useless tires on it; it's still under 22 with true 2.35/2.2s.

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## Dictatorsaurus (Sep 11, 2009)

cycloxer13 said:


> I'm running lower pressure. 16.5 front, 19 rear, +/- depending on the conditions


That's very low pressure. I haven't come across anyone riding wider rims that was able to run that low without denting the rims. Good for you.


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## cycloxer13 (Oct 27, 2014)

For a racing application, narrower and lighter can still be faster. It really depends on the course and conditions. For fun trail riding, I'd take a wider carbon rim over a narrower rim every day of the week.


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## cycloxer13 (Oct 27, 2014)

They are carbon rims and I am running Maxxis EXO TR tires - 2.4 front & 2.25 rear. It's an incredible trail setup. My buddy running 35's can get away with even lower pressure. The highest pressure I ever run now is 18F & 20R. Also, I weigh 145#. That makes a big difference too.


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## rockman (Jun 18, 2004)

Dictatorsaurus said:


> That's very low pressure. I haven't come across anyone riding wider rims that was able to run that low without denting the rims. Good for you.


It depends on the trail. And of course, riding style. I grew up on hardtails and rigid forks so still finesse my way through rock gardens than plow over them.

I ran 13 and 15 psi F and R, respectively on Derby rims in Oakridge last summer. Maxxis HR2 and Ardent. No issues. I weigh 210# kitted up.

That was partly by mistake, as I hadn't checked my pressure in a couple of days so probably wouldn't go that low again. 17 and 19 psi is more the norm for me. Flagstaff and Sedona makes up 90% of the riding I do.


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## Miker J (Nov 4, 2003)

cycloxer13 said:


> Wider rims are better. I used to race pro XC. I am a mechanical engineer by trade. Take it for what you will. It's just my opinion. I also own a fat bike with 4.6" tires on 90 mmm rims. That is fine for snow, but too wide for dirt. My Evil is running 30mm rims and 2.4 Maxxis tires. I consider it the bare minimum these days. Again, just my subjective opinion.


I'd like to hear your thoughts.

Are your rims 30mm internal width?

I like Maxxis tires a lot and I question if I went overboard with the Derbys at 34mm internal width, 40 external. The DHF/DHRII combo is still a favorite of mine.


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## cycloxer13 (Oct 27, 2014)

I'm running 30 external with 2.4 and 2.25 Ardents. The 30 is perfect for the 2.25, though if I were to do it again I'd run a 35 with the 2.4 on the front. My friend is running 35 external with High Rollers and they blow up pretty big. I think this would be a good size for the DHF and DHR's too. On the fork it is okay, but you have to watch your frame clearance. We both run Pike's on Evil The Followings (which don't have great rear triangle clearance). I have seen guys running 40's on Pike's.

Also, I am blown away by how much better the Maxxis EXO TR tires are compared to the whimpier XC tires. They may be heavier, but they ride so much better on real world trails. It's worth the trade-off on a trail bike imho.


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## Mountain Cycle Shawn (Jan 19, 2004)

This tread needs a picture!


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## jpa102 (Jul 26, 2014)

I'm running 32 external (29.3 internal) rims with 2.4" Ardent EXO's at 17-18 psi. Amazing improvement over the stock wheels with 2.2 x-kings. Completed the Wilderness 101 with this setup with no rim damage and I run 200# kitted out. I also have a fatbike with 4.6" tires for when its is wet and squishy, but love the 2.4's when the trails are dry.


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## rehammer81 (Jun 18, 2010)

I'm a big fan of Nox wheels. I'm thinking of going with their Kitsuma (36mm internal) up front and Farlow (29mm internal) in the rear. My thinking is I like a 2.4-2.5" tire up front but typically not bigger then a 2.3 out back. I think, at least currently, a lot of 2.3s get too squared off with these super wide rims greater than 30mm internal.


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## cycloxer13 (Oct 27, 2014)

rehammer81 said:


> a lot of 2.3s get too squared off with these super wide rims greater than 30mm internal.


They do. My 2.25 Ardent is fine on 25 internal. My friend has the same tire on 30 internal and you can see the tread sits a little flatter. It is subtle, but if you put the two wheels side to side you can see the difference.


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## dirtrider76 (Sep 19, 2012)

FWIW I rode a 2.7-2.5 in front and a 2.3 in back for the profile. I always liked the way the rear felt with a kind of squared off tire and a rounded one in front.


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## oldranger (Apr 14, 2011)

Hi folks. Another year in the books; two years since I started this thread on Downhill Rims so I think I'll do another drive-by on some of my favorite internet friends: 

Still no breakthrough with wide DH rims for the 2015 year. Fastest guys on the UCI WC DH circuit still running 500g rims with a 25mm inner width. I took first place in 40+ Cat 1 in our regional three race series on 2 year old DT FR600s and had tons of fun on them. 

Maybe 2016 will be the year. My opinion: save your money.


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## MTBMILES (Dec 27, 2007)

oldranger said:


> Hi folks. Another year in the books; two years since I started this thread on Downhill Rims so I think I'll do another drive-by on some of my favorite internet friends:
> 
> Still no breakthrough with wide DH rims for the 2015 year. Fastest guys on the UCI WC DH circuit still running 500g rims with a 25mm inner width. I took first place in 40+ Cat 1 in our regional three race series on 2 year old DT FR600s and had tons of fun on them.
> 
> Maybe 2016 will be the year. My opinion: save your money.


My opinion is buy what you want and have fun.

Sent from my iPhone using Tapatalk


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## oldranger (Apr 14, 2011)

MTBMILES said:


> My opinion is buy what you want and have fun.
> 
> Sent from my iPhone using Tapatalk


I love wandering in to this ambush zone. You guys can't shoot straight.
RLTW.


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## MTBMILES (Dec 27, 2007)

I would never shoot at a Ranger 


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## meltingfeather (May 3, 2007)

MTBMILES said:


> My opinion is buy what you want and have fun.
> 
> Sent from my iPhone using Tapatalk


Hey! That's what I was going to say! :thumbsup:


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## AndrewBikeGuide (Nov 12, 2014)

Whenever a post starts with ".... Fastest guys on the UCI WC DH circuit still running 500g rims with a 25mm inner width." after I pick myself up from laughing so hard at this "science". 

Firstly, for 99% of the lurkers on this forum the only time they hit WC speed on their bicycle is downhill on a wide, paved, empty of traffic street, certainly not on a WC standard track. Speed generates forces on tyres and rims that put those riders into a seperate set of variables to us mere mortals. 
Secondly, quite a few of those riders are on product we have not seen yet and might not ever see the inside of (despite spy shots) and teams are good at 'branding' prototypes so they look like current product and re-branding non-sponsor product to look like sponsor product.
Thirdly, and probably most important, they have contracts and run what they are provided to a large extent so there not any element of choice.

And "I took first place in 40+ Cat 1 in our regional three race series on 2 year old DT FR600s and had tons of fun on them." well done you and I am glad that you had fun but hardly WC level speeds so not really any support to your theory of the validity of wide rims.

It is reasonably well established that wide rims allow tyres to run slightly lower pressures which deliver measurable traction advantages at most speeds used by mortal mountain bikers. As always one must realise that the DH market it one of the smallest and most expensive segments of the bicycle sales empire and as such one of the lowest priorities for new product in many ways.

Most importantly is that you are having fun so do it on what ever works for you.


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## Mountain Cycle Shawn (Jan 19, 2004)

AndrewBikeGuide said:


> Whenever a post starts with ".... Fastest guys on the UCI WC DH circuit still running 500g rims with a 25mm inner width." after I pick myself up from laughing so hard at this "science".
> 
> Firstly, for 99% of the lurkers on this forum the only time they hit WC speed on their bicycle is downhill on a wide, paved, empty of traffic street, certainly not on a WC standard track. Speed generates forces on tyres and rims that put those riders into a seperate set of variables to us mere mortals.
> Secondly, quite a few of those riders are on product we have not seen yet and might not ever see the inside of (despite spy shots) and teams are good at 'branding' prototypes so they look like current product and re-branding non-sponsor product to look like sponsor product.
> ...


Extremely and eloquently well said!!


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## cycloxer13 (Oct 27, 2014)

wide carbon rims are the future - everything else is yesterday's technology - every single bike i own is running carbon rims now


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## oldranger (Apr 14, 2011)

You know what's funny, and what makes me laugh? OK, I'll tell you anyway:

I think it's funny how many people are still looking at this thread if the premise is so bogus. This is thread is the #3 most Replied to, and also in the Top 10 most Viewed threads on this 'Wheels & Tires' Forum. It gets a ton of traffic, and some of you (us) just can't stay away from the discussion. I started it when I had only two years of experience with DH, and it was my first thread I started on this board. I think I've started all of three threads on this whole MTBR Forum and the other two are about kids bikes.

Andrew - welcome to the topic. Please start at the beginning of the tread and read all of it. (I bet you think that's funny too). You're a guide at Whistler and ride a bike with Enve DH wheels that have a $3,000 (USD) pricetag. Hold on, let me pick myself up - that's hilarious. I can't believe you spent that much on a set of wheels (Eh). My wheels have great hubs, but they only cost me $750 to build. You are special - I am not. You are right, Andrew - I'm slower than WC racers. I'm actually about 15%-20% off of WC DH speed when I'm on the same tracks. But I am also 20+% heavier than they are. So then, I think comparisons are probably a bit complicated either way.

For the public: I still have not seen DH riders on the Eastern side of the US adopting wide carbon rims for Downhill use. Not the WC athletes riding here, not old guys like me, not the new riders either. And again in 2016, the major bike manufacturers are NOT spec'ing their DH bikes with carbon rims. Maybe 2016 is the year where a 2-Ply DH tire comes out that works well with wide rims. I don't know. But - if you're a regular guy like me, or a parent wondering how to outfit their kid's bike for DH racing - my recommendation still stands that your money will be better spent on gas to the mountains and lift tickets.

There are some good aluminum wheels coming out with a 27.5mm inner width. That is greater than the 23-25mm I believe is optimal - so I'm waiting to see how that goes. Maybe I'll try some of them.

Cheers.


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## sherwin24 (Jul 23, 2010)

Just ordered some wheels. 29mm internal front and 26 rear. Took my wife's advice I mentioned somewhere earlier in this thread. Bigger in front is better and a bit less girth is the rear is a nice compromise.


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> You know what's funny, and what makes me laugh? OK, I'll tell you anyway:
> 
> I think it's funny how many people are still looking at this thread if the premise is so bogus. This is thread is the #3 most Replied to, and also in the Top 10 most Viewed threads on this 'Wheels & Tires' Forum. It gets a ton of traffic, and some of you (us) just can't stay away from the discussion. I started it when I had only two years of experience with DH, and it was my first thread I started on this board. I think I've started all of three threads on this whole MTBR Forum and the other two are about kids bikes.
> 
> ...


^ Oh, I see how it is. What we have here is a poor, older, slow, fat guy that can't afford to spend, "$3000" for a set of wheels. So, in order to justify that in his little mind, he has to belittle others who can afford wide rims and has to convince himself that wide rims are not the future. Oh, and you can build a set of the best wide set of wheels with Derby rims, Hadley hubs, DT spokes and Sapim Polyax nipples for $1400. That's a very good price for what you get, considering the cost of good mountain bike stuff these days. It's not a cheap sport. And BTW, you only have a lot of reviews and replies because 97.4768% of the people replying disagree with you. Also, the DH scene at the WC level is the smallest mountain bike demographic there is. What happens at that level and even at the slower levels means absolutely nothing to the rest of us. He average mountain biker wants stability and traction. Wide rims provide that for us.


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## AndrewBikeGuide (Nov 12, 2014)

@oldranger. I completely agree with you in fact re the value of carbon wheels. The prices are ridiculous, hand building in the US and all that not withstanding. And if you think a bike guide can afford to buy anything at full retail you have not asked your instructor what his/ her wages are. Luckily some brands are happy that guides are telling students about their products.

My DH ENVE wheels do in fact support your position that wider is not necessarily better as they have a 23mm innner (by my verniers) and have done a fantastic job of holding my heavy ass off the ground for three years now. I can run relatively low pressures anyway as I run UST DH tyres set up tubeless and I ride with care rather than raw speed as I am too old for hospital visits and body rebuilds. I also need to ride at speeds that students can cope with whilst learning new skills and tactics so most days are at slower speeds than I would normaly choose to ride at. After seven seasons of 100+ days when I am not teaching/ guiding DH in the bike park I am riding regular trails that require pedalling and provide variety that sometimes appears to be lacking in the park.

At 230 lbs (with my guide pack on) I am definitely much heavier than most WC riders and have no interest in their speeds (other than to admire during Crankworx). That said my heavy ass does work a bike, suspension, wheelset and tyre so it shows how strong the wheels are to stand up to 250+ days of use with only one broken spoke to show for it (stick in spoke). 

So I also have a lot different cost to use ratios for my bikes and bike equipment than most riders who are not full time guides. 

There are many great rims and wheelsets that take a rider into the 27mm realm without spending silly money. And I would recommend them to anyone who asks about a foray into the realm of the wider rim as I understand that not everyone wants, can afford, needs or will benefit from carbon rims.

That said I have a set of Light Bicycle 35mm (30 mm inner) on Hope Pro Evo hubs which cost me about what you built your wheel set for (go that strong US dollar) and they make a noticable difference, 2-3 psi less pressure which allows more grip, over my M70/30 wheels when trail riding with the same tyres mounted. 

On the parents thing, yes I see this as a guide and whilst I empathise I would observe that as no one has ever made people marry and breed so it is like anything in life, a choice that one lives with. I chose no children (which means no school fees, no camps, no college fees and no arguments about screen time and bed times) so whilst some might think that I will be sad and lonely in my old age, I'll actually be that guy who can do what ever he wants, whenever he wants, with a smile, on his really nice mountain bike.

On a separate note the whole carbon thing is making me pause anyway as I am starting to agree with Max Commencal and Gavin Michael Vos (Spank) that aluminium is more than enough for 95% of mountain biking applications and has the advantage of being recyclable when it wears out/ breaks.

So I agree with quite a bit of what you say actually and apologise if it did not come across that way. But wider (27-30mm) (not stupid wide) will have benefits for the majority of normal riders who are choosing to mount 2.35" to 2.5" tyres as they can run lower pressures for more traction in most trail conditions at most trail speeds.


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## AndrewBikeGuide (Nov 12, 2014)

Nice looking wheelset!! Red is not my thing but they look great. What bike are they going on?


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## Mountain Cycle Shawn (Jan 19, 2004)

AndrewBikeGuide said:


> Nice looking wheelset!! Red is not my thing but they look great. What bike are they going on?


Thanks! A Santa Cruz Nickel in long travel mode. 150mm up front and 145mm in the rear using a 57mm stroke shock that has the same I to I length as the original 50mm stroke shock. Weight is just under 27 pounds. The next mod will be going to a 1x11 using the e-Thirteen 9x44 cassette with an oval NW 28T ring up front. That should bring my weight to around to 26 pounds. It's a blast to ride!


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## dirtrider76 (Sep 19, 2012)

Odd I just laced up a pair of 25mm internal wheels after riding 30mm internal wheels for 2 years.


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## oldranger (Apr 14, 2011)

AndrewBikeGuide said:


> But wider (27-30mm) (not stupid wide) will have benefits for the majority of normal riders who are choosing to mount 2.35" to 2.5" tyres as they can run lower pressures for more traction in most trail conditions at most trail speeds.


Andrew, 
Out of curiousity - when you're riding by yourself in the bike park on your DH bike, what tire pressure do you typically run in the rear? For simplicity, let's say you're staying in the Fitzsimmons Zone, and you've ditched some of the gear you have to lug around while guiding, and you're going out to ride hard.

(I've looked at the details you've included. I'm a bit lighter at 190+ gear)

Then, on the trails where you use your trail bike - what PSI do you run and what is the inner width on that Enve rim?


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## cycloxer13 (Oct 27, 2014)

I'm 145# plus gear 150# Carbon all the way, bro.


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## AndrewBikeGuide (Nov 12, 2014)

@ oldranger

DH/ Bike Park, riding for myself with little/ no gear:
Favourite trail/ combo: Angry Pirate/ Samuari Pizza Cat/ Afternoon Delight/ Lower Whistler DH/ Monkey Hands.
Bike/ Wheels: Santacruz Bicycles V-10.5 26" running ENVE DH (23 mm inner width) on DT240S:
Spring (dry)/ Summer: Continental Trail King Protection UST 2.4" front (26 psi) and rear (29 psi), I will up this to 28 psi front/ 31 psi rear if we are hitting mainly fast jump trails (A-Line or Dirt Merchant).
Spring (wet) & Autumn: Continental Der Kaiser Projekt 2.4"; front 25 psi and rear 28 psi. I add 2 psi to the tyres if mainly jumping.

Trail riding (normally roadie shirt w 1 water bottle, snacks, phone and min-tool/CO2, 1 water bottle on the bike):
Favourite trail/s: Microclimate, Howler, High Society (Whistler) and Credit line and Rupert (Squamish).
Bike/ wheels: SC Nomad CC 27.5 w ENVE M70/30 (25 mm inner width) on DT240S.
Spring (dry)/ Summer: Continental Trail King Protection Apex 2.4" front (22 psi) and rear (24 psi).
Spring (wet) & Autumn: Continental Trail King Protection Apex 2.4"; front 20 psi and rear 22 psi.

Bikes

I have been trying WTB Breakout TCS Tough 2.4" tyres recently; "High Grip" front and "Fast Rolling" rear at 21 psi front and 23 psi rear. They are pretty good but quite a bit heavier than the Continentals and not as fast rolling or tacky. They seem to have stupid tough side walls however so I will probably use them more in Pemberton which is a bit of a sharp rock/ side wall slash fest.

I have been too lazy to switch these to the LB wheels to try them there (all the trails are covered in snow and I am on post ACL riding restrictions so it is all spin bike at the moment).


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## Mountain Cycle Shawn (Jan 19, 2004)

^ it's nice to hear someone isn't running stupid low pressures.


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## kosmo (Oct 27, 2004)

dirtrider76 said:


> Odd I just laced up a pair of 25mm internal wheels after riding 30mm internal wheels for 2 years.


I would love to hear your reasoning. I'm waffling between 26 and 29 internal, both Nox rims.


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## oldranger (Apr 14, 2011)

Thanks Andrew. The information you put in your response was helpful. Let's say, hypothetically you were going to build a new 2016 DH bike with 27.5 wheels. Let's also add that you can't get Enve's. 

What kind of wheelset would you choose?


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## dirtrider76 (Sep 19, 2012)

kosmo said:


> I would love to hear your reasoning. I'm waffling between 26 and 29 internal, both Nox rims.


Unless I ran a pretty wide tire I had lots of sidewall damage to tires even on some of the wide ones. To be honest I killed the sidewall on almost every tire I ran on them. I dug them with 2.7 wide tires on them but most people don't run a 2.7 DH casing tire anymore. Heck even the rim seemed to be beat up a bit more since its more exposed. My rear rim was trashed and my 23mm internal wheels held up good and has less tire failures on my other bike. So I split the difference and a 2.3 fills out perfect on the 25mm internal rim.

Up until build my HT a year ago I've had 28-30mm internal rims forever. See how these work out this season. I was seriously going to run LB's 38mm carbons then decided not to and built trail295s instead. Build was the same weight and a lot cheaper.


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## NWRyder (Jul 28, 2012)

I wonder why MX bikes use 110mm tires on 2.15 inch rims? With all the time and money put in testing you would think they would realize how much better traction and cornering they could get with rims almost as wide as their tires.


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## Mountain Cycle Shawn (Jan 19, 2004)

NWRyder said:


> I wonder why MX bikes use 110mm tires on 2.15 inch rims? With all the time and money put in testing you would think they would realize how much better traction and cornering they could get with rims almost as wide as their tires.


Motorcycle tires are very heavy and very strong.


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## Le Duke (Mar 23, 2009)

We really, really need to get away from making comparisons to vehicles with several orders of magnitude more power and 5-10x the weight.

Sent from my XT1585 using Tapatalk


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## Zowie (Aug 3, 2013)

^^Yeah. Good point.

I wonder why tanks use treads?
Are we missing out?


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## AndrewBikeGuide (Nov 12, 2014)

NWRyder said:


> I wonder why MX bikes use 110mm tires on 2.15 inch rims? With all the time and money put in testing you would think they would realize how much better traction and cornering they could get with rims almost as wide as their tires.


Just not even a relevant comparison, percentage of overall weight of tyres not even close, unsprung to sprung weight ratio, weight of motor bike normally as much or more than the rider rather than the other way round with mountain biking. Power to weight ratio. No pedal action so no pedalling dynamics.

In fact that was just a thoughtless question so I am wasting my time addressing it. If you really want to know start a thread.


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## NWRyder (Jul 28, 2012)

AndrewBikeGuide said:


> Just not even a relevant comparison, percentage of overall weight of tyres not even close, unsprung to sprung weight ratio, weight of motor bike normally as much or more than the rider rather than the other way round with mountain biking. Power to weight ratio. No pedal action so no pedalling dynamics.
> 
> In fact that was just a thoughtless question so I am wasting my time addressing it. If you really want to know start a thread.


I'm sorry, but I don't see what any of these factors have to do with the ideal ratio of rim width the tire width. What makes bikes different? I have not followed this fad, but from what I understand, people run tubless and think they should have 18psi in a single ply tire. Then the tire rolls in corners and burps easy. So they get really wide rims. Then the sidewall if vertical and the tire has less compliance, so they run 15psi. Now we need special tires to provide a proper profile on 40mm rims and sidewalls wear out before the tread. (I wish I was exaggerating but I read a few pages of this thread)

I am just skeptical because I have been riding a long time and seen many tends come and go. I have seen the majority of forum users endorse them, even when the trend completely reverses over the years. i.e. really high bars, to really low bars.

And I wish people would not so easily dismiss the moto wold. Suspension forks sucked for about a decade because people thought it was not a "relevant comparison" so we had all these goofy linkages and elastomers other crap when really we could have just scaled down the technology which was already there. Same with brakes.


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## AndrewBikeGuide (Nov 12, 2014)

Because in my case my 2.4" mountain bike tyre is not supporting 210 kg of 60 hp dirt bike at an average speed of 50 kmph.

It is supporting a combined 107 kg of 0.5 hp (if I am dreaming) pedal mashing mountain biker at an average speed of 20 kmph.

And, as you mentioned, people still insist on trying to run noodly, single ply tyres on 150-160mm travel bikes rather than accepting that they have made a huge weight saving with their carbon rim build anyway and riding proper tyres like the Apex Protection case, TCS Tough case or new Double Down case. Even worse they are trying to run low pressures whilst running tubes because some other forum lurker said that the Stans leaked through his sidewalls one time!!

I have no idea how many plies Dunlop, Bridgestone or Metzeler use in their off road dirt bike tyres but I am guessing that it is lots more than on a mountain bike tyre, then there is whole larger chunk of rubber added to that. There really are just so many different variables that the comparison in this case really is basically a waste of time. It might be an interesting engineer geek out topic over a beer at the pub sometime but that is about it.

It is pretty simple maths for a bicycle tyre at the moment and ENVE have summed it up in their recent rim/ wheel chart. Buy the width rim that you need for 90% of your riding based on the width of tyre you think you will be running. Also if you are trying to do everything with one bike then suck it up and buy a second set of wheels.

This is a sensible chart, apply it to any wheel, not just carbon fibre, if you run tubes add some more air or you will pinch flat (and get into 2016 and go tubeless):









Good page here: Is wider always better? - ENVE Composites

One also has to remember that this forum has quite a few 'riders' who have a 160mm travel bike with a 65º head angle, designed to be ridden down steep trails at a stupid fast speed, but they are running 170 mm forks and 2.5" tyres on 40mm wide rims because some thread said that is what all the cool kids are running and 90% of their riding is on almost flat, buffed single track that my granny could negotiate faster in her zimmer frame and then they are complaining about scuffing rims and poor steering and high rolling resistance (there is even one comedian who is trying to tell us that a 2.5" Kenda Nevegal is a great tyre!! But if he is happy riding his franken bike with his Nevegals then good on him). Or worse they have bought 35mm rims and are still running 2.1-2.2" tyres on them but have their suspension set ot 25% sag and wonder why the tyres and rims are taking a beating (read the Nox thread).

Wider is not automatically better but slightly wider does being noticable benefits to a lot of riders who know how to sensibly combine riding style with bike, wheel (rim width) and tyre choice.

Well this has been fun, if it was not snowing I would go for a ride. Hopefully everyone can head out for a ride and work out whether their rims are too skinny, too wide or just right.


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## Zowie (Aug 3, 2013)

AndrewBikeGuide said:


> Well this has been fun, if it was not snowing I would go for a ride. Hopefully everyone can head out for a ride and work out whether their rims are too skinny, too wide or just right.


If you had 100mm rims and 4.8 tires, you wouldn't have any problems...

Is that hype? :lol:


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## AndrewBikeGuide (Nov 12, 2014)

@Zowie

Hilarious :thumbsup:

Then I will run into that other factor of mountain bike ownership which is that my wife refuses to acknowledge the truth of the "N+1" rule.

Funny thing is that I have been trying to justify a fat bike but can't really be bothered to make a new longer rack for the storage aspect and I know, as a serial upgrader, it will turn into another "pimp my ride" exercise for a bike that is esentially doomed to disolve due to the salt treatment on the roads in winter.


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## NWRyder (Jul 28, 2012)

Thanks AndrewBikeG. It is pouring rain where I am at which is why I am here instead of testing my brand new Continental baron 2.4 projekt wonder tire. I have noticed that this Continental, and the Super Gravity tires they replaced, basically weight what old downhill tires did, such as the Kujo. Even a modern 2.5 DH dhf is only a bit heavier and most of that is probably the steel bead. For me, a thin wall tire just never feels right cornering and blasting over rocks although I wish I could find a light tire which did. With what modern 160mm travel bikes are capable of I think we just have to live with the weight regardless of what material and width our rims are.

I thought of motorcycle tires because everything is a compromise and I wonder what the compromises are to a wide rim? The start in a MX race is super important so I know traction is a top priority. There is not much to pinch flat a tire on a groomed track so I think they run higher pressure to reduce roll over. So the goals of traction and reducing tire roll are there. I just was thinking there must be a downside. Weight is an obvious one but I don't know what else is. Cornering, sidewall compliance, the risk of destroying a rim, etc? Maybe none of this is applicable, but that is what I was getting at. Also if pro downhillers and enduro riders have a sponsor which produces wide rims, yet they do not use them, there must be a reason as these guys do test gear to find any advantage. There reasons may not apply to us, such as enduro guys can't replace their rims and they can almost always band an aluminum one into shape, but I would be curious what their reasons are.

I also ask because I think tubeless setups are a driver for wide rims. For me, I run more air tubeless then I do tubed to keep from burping tires. Also the burps and completely blowing off tires have made me too scared to drop the pressure much. Maybe I am a hack though. I do not have thorns where I live, and with a heavy sidewall I don't get much for pinch flats anyway, so I am currently debating whether tubeless is a benefit for me. Maybe wide rims would solve all this but I am not sure. Would a traditional width tubeless design such as a UST Maxxis 823 rim be the most secure setup, or something wide? I have some Canfield rims which they claim are tubeless compatible with tape but I guess that applies to any rim. When I deflate them the beads come loose which is not giving me a good feeling. I will test though, with a full face helmet, and see.

Here are my skinny rims in an obsolete diameter setup tubeless and waiting for some decent weather.


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## AndrewBikeGuide (Nov 12, 2014)

Nice front tyre (and a really nice bike) I have been waiting for Continental to actually release them to someone other than the mountain bike press. It is what I want to run this season on my front wheel. I will be running a Trail King 2.4" Protection on the rear though.

Truly an interesting discussion and I see your point now but the two disciplines are mechanically so different even if some of the issues/ condierations are the same. I don't think I ever worried once about burping or pinch flatting my tyres when I had a DR250 dirt bike. I agree that tyre construction is important and Maxxis has realised this with their DD case and Schwalbe has their system with stronger sidewalls but supple tyre crown under the tread (it is a pity their sticky rubber rolls so slowly and the knobs tear off in 2-3 weeks of riding). Apex does a similar thing for Conti even though is was designed to stop snake bite punctures and side wall slashes. 

Running tubeless with more air than when running tubes is outside my experience. 

I last used a tube five years ago shortly before I went tubeless on my DH bike for guiding in the park. In about 500 days of park riding I have had exactly three flats, one due to a nail after trail crew re-newed some wood work and two failed beads on a bad batch of Trail King 2.4" x 26" UST Protection tyres (the good one that are made in Germany) which Continental warrantied. Since getting rid of tubes I have consistantly run 3-5 psi less than I used to run with tubes. I am pretty heavy and do not have the greatest proprioception in my legs so my wheels and tyres get a hard time and I guess I have burped the rear tyre 2-3 times. That said when I am riding jumps trails I tend to run higher pressures (but still not that high for my weight compared to some riders) to reduce the chance of burping in berms and deforming the tyre when pressing into the take off ramp of jumps. I guess I would rather burp a tyre and walk rather than slide out on an off camber root or dusty off camber rock and take a full body fall on the chin. Each to their own on that decision cycle.

I don't know the tech specs on the Canfield rims but I do know that they know what they are doing as far as riding goes (they are pretty regular riders in the bike park).

I have run the silver Deemax (24mm inner?) for two seasons with no troubles, FR600s (24.9mm) for half a season with no trouble and then ENVE DH (23 mm inner) since then.

On the trail I have 12 year old Mavic 521 Ceramics that hold tubeless well (hooked bead design/ 21 mm inner), Sun Ringle Charger Pro 26" (23 mm inner - hooked), XTR Trail M988 26" (21mm inner hooked UST), Light Bicycle 35 (29.5mm inner hookless) and ENVE M70/30 (25mm inner hookless) and I have not had any trouble with any of the wheels tubeless (other than slowly going flat when you don't ride them for 4 months in winter).

The Charger Pros currently have Race King 2.2" Protections at 45 psi as they are on my pumptrack bike. I don't think I would trust them so much with a 2.4" tyre mounted to them.

I run 22-24 psi on my ENVE M70/30 with most tyres, I found that the Mountain King 2.4" was pretty pressure sensitive actually and the sidewalls puncture (rock slies) too easily so I have stopped using them (although I really like them). Would I have asked for the M70/30 HV if they were available when I got my wheels, almost certainly but I am not complaining as they are awesome wheels.

So looking at the that list I do not own any really wide rims (30mm +). I do know that I will always chose the 25mm+ inner width wheels over anything narrower. I can definitely feel the difference in tyre stability between the 21mm ish rim and the 25mm rim and it makes a difference to my riding and my confidence. I also appreciate being able to run 2-3 psi less and the extra traction that I gain as a result. But I ride black or double black trails most days following 25 year old bike ninjas who have super riding skills so I appreciate every little extra bit of traction that I can get (within reason) so I can avoid crashing too badly.

I think somewhere between 25mm and 30mm is the magic number for the type of tyre I use and the riding that I enjoy. I can see a place for wider rims if one is using wider tyres such as those proposed for the new plus size. I will hold off judgement until I get to try one (probably at Crankworx Whistler this year) but at the moment I cannot see a weight versus benefit positive in going bigger than 2.4" so I am happy with my wheels.


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## Mountain Cycle Shawn (Jan 19, 2004)

Ok, you want us to read all that?


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## NWRyder (Jul 28, 2012)

The Canfield rims are 23mm inner. They were half priced for the 26 set so I thought I would try them.

Universal has the new baron in stock, at least in 26.

Just a warning, if you run a 2.4 TK I think you will end up with a much larger rear tire (if you care about that). For my baron, after a day at 50psi, the casing is only 57mm. For reference the MK on the rear is measuring 60mm. Maybe after some time they will be the same width. But I also have a TK 2.2 and I think I remember it being almost exactly the same casing width as the MK 2.4. I do not have a TK 2.4 but I think they are huge.

The MK on the rear might be a bit lighter duty then I need but it is what I had so I will try it and not drop the psi too low. I would like the projekt casing in the MK or TK for the rear. I think they might make this now, not sure. Also I would want the harder rubber. They both say black chili but the baron feels much softer to me so I think it would drag on the back but can't say for sure.


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## Guest (Jan 18, 2016)

NWRyder said:


> I wonder why MX bikes use 110mm tires on 2.15 inch rims? With all the time and money put in testing you would think they would realize how much better traction and cornering they could get with rims almost as wide as their tires.


Taking those numbers at face value, a 110mm wire tire on a 55mm IW rim would require a 310mm b2b. that would yield a b2b/IW ratio of 5.64. The casing width/IW ratio is only 2:1.

5.64:1 IS a wide rim ratio by MTB tire standards. On a 2.4" tire that would require a 28mm IW rim, pretty much exactly what is advocated for tires of that size.


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## keen (Jan 13, 2004)

Not to steer this thread too far off but mx tires are an aple to oranges comparison imo. Put a rear mx tire in your hand and you will notice it is very rigid. Take a look @ the bead it has a serious step that places the rim deep in the bead channel - protects the rim / aids in bead locking?


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## oldranger (Apr 14, 2011)

Thanks again Andrew for what you've added to v2016 of this discussion; I appreciate your attention to detail. One interesting thing that caught my attention on the Enve pressures chart is the significant difference between the recommended psi for M70 VH and M90. For the weight group of 180-200lbs. the recommendation is 7 PSI higher for the M90 wheels. The M90 are purpose built for "downhill riders and racers", and I think it's fair to assume a dual-ply casing in the model. The M70 HV are for "All-mountain gravity aficionados that appreciate human powered ascents as a means to an end" 

Note for readers: per Enve both the M70 HV and the M90 are internal width 25mm. 2016 spec.


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## Rick Draper (Dec 1, 2009)

oldranger said:


> Thanks again Andrew for what you've added to v2016 of this discussion; I appreciate your attention to detail. One interesting thing that caught my attention on the Enve pressures chart is the significant difference between the recommended psi for M70 VH and M90. For the weight group of 180-200lbs. the recommendation is 7 PSI higher for the M90 wheels. The M90 are purpose built for "downhill riders and racers", and I think it's fair to assume a dual-ply casing in the model. The M70 HV are for "All-mountain gravity aficionados that appreciate human powered ascents as a means to an end"
> 
> Note for readers: per Enve both the M70 HV and the M90 are internal width 25mm. 2016 spec.


You need to check facts. M90's are 25mm internal, M70 HV's are 31mm internal.

M60 HV's are 26mm internal.

Specs per 2016 Enve HV rims.


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## Deerhill (Dec 21, 2009)

*nice riding*

@ Oldranger, congrats on the first place 40+ Cat 1


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## oldranger (Apr 14, 2011)

Rick Draper said:


> You need to check facts. M90's are 25mm internal, M70 HV's are 31mm internal.
> 
> M60 HV's are 26mm internal.
> 
> Specs per 2016 Enve HV rims.


I did check the facts on the Enve website. But I guess I didn't dig deep enough. Their page here: M Series 70 Thirty / 70 Thirty HV - ENVE Composites doesn't indicate different 'Quick Specs' based on different selections in the option field.

Rick - Where is the information on the detailed rim specs?


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## Rick Draper (Dec 1, 2009)

Flick through the photo so at the top of the m70 page and you can find a photo showing the internal widths.

M70 is 25mm internal M70 HV is 31mm internal.


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## evasive (Feb 18, 2005)

From today's Fort William pit randoms:

"The Syndicate's New ENVE Rims
Greg Minaar's mechanic, Jason Marsh, mentioned at Lourdes that they had a new rim system that helps to avoid punctures. He wouldn't confirm if they are 'un-puncturable', and after all, the Titanic was meant to be unsinkable and we know what happened there... We can't tell exactly what it is but it's some kind of tough plastic cover or rim-strip on a new wider rim which measures 44mm (external) and which we can guess will provide a hookless 34mm internal dimension."
http://www.pinkbike.com/news/randoms-fort-william-world-cup-2016.html


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## oldranger (Apr 14, 2011)

Hi Folks. OP here. Two years in to this thread that is about downhill tires - the fastest Downhill (DH) riders in the world are still running aluminum rims that are less than 500 grams and have a 25mm inner width. I know that wider rims are gaining popularity in trail riding and Enduro racing. I also see some tire manufacturing making trail (not DH casing) tires and marketing them for wider rims. I also recognize the Syndicate is a well funded exception to that 'rule'. But I still think this wide rim (30+mm inner width) is all marketing hype or only relevant to trail riding at lower speeds. If you want to debate trail riding and climbing ideals - start another thread. I don't have any expertise on climbing...that is my least favorite and least practices form of riding.

To the general drifters by: the East Coast USA Downhill scene is still dominated by aluminum rims with inner widths in the normal range of 25mm - 28mm.

P.S.: Aaron Gwin didn't appear slow on his EX471 rims at Mountain Creek Spring Classic Pro GRT last weekend. At 25mm inner width, aluminum, these can be found for about $100. Other Pro and Cat 1 riders that want to equip themselves with products them help them go fast are also choosing aluminum rims 25mm-28mm that can be bought for less than $80 per rim.

Cheers. Hi Mountain Cycle Shawn


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## Stonerider (Feb 25, 2008)

oldranger said:


> Hi Folks. OP here. Two years in to this thread that is about downhill tires - the fastest Downhill (DH) riders in the world are still running aluminum rims that are less than 500 grams and have a 25mm inner width. I know that wider rims are gaining popularity in trail riding and Enduro racing. I also see some tire manufacturing making trail (not DH casing) tires and marketing them for wider rims. I also recognize the Syndicate is a well funded exception to that 'rule'. But I still think this wide rim (30+mm inner width) is all marketing hype or only relevant to trail riding at lower speeds. If you want to debate trail riding and climbing ideals - start another thread. I don't have any expertise on climbing...that is my least favorite and least practices form of riding.
> 
> To the general drifters by: the East Coast USA Downhill scene is still dominated by aluminum rims with inner widths in the normal range of 25mm - 28mm.
> 
> ...


So true! If wider was faster everyone would be racing fat bikes for downhill and enduro. There is a limit for everything.


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## tigris99 (Aug 26, 2012)

There's a huge difference in what were talking about and fat bikes.

Sent from my XT1565 using Tapatalk


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## Mountain Cycle Shawn (Jan 19, 2004)

oldranger said:


> If you want to debate trail riding and climbing ideals - start another thread. I don't have any expertise on climbing...that is my least favorite and least practices form of riding.
> 
> Cheers. Hi Mountain Cycle Shawn


Hey what's up bra? So, this isn't the DH forum. And, you know how threads around here evolve. Plus, DH is such a small segment of the mountain bike population, especially the racing segment which you seem to talk a lot about. I don't want to DH and I'll never have a DH bike. So, as far as I'm concerned they could roll on pizza cutters. But for the rest of us, a good set of wide rims make riding faster, easier and safer. Stability is greatly increase in all situations, including at speeds into the 50s. Climbing is also greatly improved because of the lower pressures, bigger footprint and lack of tire squirm. In fact, I never get slip from the rear tire anymore, no matter how much weight I put on the front end. If I can't make a climb, it's because I run out of gearing and leg strength. If you have a trail bike, maybe wide rims would help you want to climb more. How much time have you spent on a trail bike with some good wide carbon rims?


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## J-Ha (Jul 21, 2010)

Before the thread gets all passionate again, I'll do my best to keep it light with a pic of a DH bike!

I have wide rims (Derby) on my DHR, and have ridden them for a season and a half. Having been so impressed with them, I included a set on my new Jedi's build for 2016.


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## Mountain Cycle Shawn (Jan 19, 2004)

J-Ha said:


> Before the thread gets all passionate again, I'll do my best to keep it light with a pic of a DH bike!
> 
> I have wide rims (Derby) on my DHR, and have ridden them for a season and a half. Having been so impressed with them, I included a set on my new Jedi's build for 2016.


Oh Jesus, someone's gonna get a jammed up camel toe over this. Do you realize this?


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## jazzanova (Jun 1, 2008)

J-Ha said:


> Before the thread gets all passionate again, I'll do my best to keep it light with a pic of a DH bike!
> 
> I have wide rims (Derby) on my DHR, and have ridden them for a season and a half. Having been so impressed with them, I included a set on my new Jedi's build for 2016.


Are those Derby 35id?
How is the thread on the Magic Mary? Is it a super gravity vertstar version?


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## Mountain Cycle Shawn (Jan 19, 2004)

tigris99 said:


> There's a huge difference in what were talking about and fat bikes.
> 
> Sent from my XT1565 using Tapatalk


Huge difference!


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## J-Ha (Jul 21, 2010)

Mountain Cycle Shawn said:


> Oh Jesus, someone's gonna get a jammed up camel toe over this. Do you realize this?


Haha! I don't fully understand your comment, but I am chuckling all the same.


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## Mountain Cycle Shawn (Jan 19, 2004)

J-Ha said:


> Haha! I don't fully understand your comment, but I am chuckling all the same.


You're giving his panties a wedgie.

Urban Dictionary: wedgie

Urban Dictionary: camel toe


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## J-Ha (Jul 21, 2010)

jazzanova said:


> Are those Derby 35id?
> How is the thread on the Magic Mary? Is it a super gravity vertstar version?


40mm od and 34mm id... for the 27.5 DH rim. Yes, super gravity vertstar version tires.

The tread is a bit more rounded on these tires, on the wide rims, than the DHF/ DHR II combo I am running on the DHR. Unfortunately, that's the extent of my knowledge, as I didn't experiment with any other tire combos.


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## jazzanova (Jun 1, 2008)

J-Ha said:


> 40mm od and 34mm id... for the 27.5 DH rim. Yes, super gravity vertstar version tires.
> 
> The tread is a bit more rounded on these tires, on the wide rims, than the DHF/ DHR II combo I am running on the DHR. Unfortunately, that's the extent of my knowledge, as I didn't experiment with any other tire combos.


How are the sidewalls compared to the thread? Are they any wider?
How is the cornering on the side knobs?


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## J-Ha (Jul 21, 2010)

jazzanova said:


> How are the sidewalls compared to the thread? Are they any wider?
> How is the cornering on the side knobs?


My answers are probably going to sound a bit generic, as I think they ring true across the board as the interface between wide rims and tires evolve... 
-The sidewalls are more upright to a tread pattern that is a "flatter" and "squared off" at the shoulders. 
-No, I do not believe the tire is any wider. Admittedly, I have not measured this.
-The cornering is hard to gauge, as I had also been working on my technique as I was riding these wheels. I do not feel that wide rims will make or break one's cornering prowess... but technique will.

From the Duryea, DH race 2015:


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## Guest (Jun 3, 2016)

J-Ha said:


> Before the thread gets all passionate again, I'll do my best to keep it light with a pic of a DH bike!
> 
> I have wide rims (Derby) on my DHR, and have ridden them for a season and a half. Having been so impressed with them, I included a set on my new Jedi's build for 2016.


nice lookin sled mate:thumbsup:


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## AndrewBikeGuide (Nov 12, 2014)

NWRyder said:


> The Canfield rims are 23mm inner. They were half priced for the 26 set so I thought I would try them.
> 
> Universal has the new baron in stock, at least in 26.
> 
> ...


I did a side by side on the TK 2.4" on a wider rim (NOBL TR38) and it was fascinating that the contact patch was slightly narrower (but resulting in more support for the side knobs). Blog here: Exploring wider rims | bikeandskiblog


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## GTscoob (Apr 27, 2009)

AndrewBikeGuide said:


> I did a side by side on the TK 2.4" on a wider rim (NOBL TR38) and it was fascinating that the contact patch was slightly narrower (but resulting in more support for the side knobs). Blog here: Exploring wider rims | bikeandskiblog


This makes sense, as you spread the beads apart on a tire designed around a narrower rim, the sideknobs will stand more vertical, thus giving a slightly narrower stance. Going too wide on a rim on a tire designed for a narrower rim really narrows how far you can lean the bike as well, those same few degrees more vertical that the sideknobs stand are a few less degrees you can lean the bike before losing your cornering knob.


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## slowride454 (Jan 11, 2014)

I wonder if I can fit my 29x3.0 tires on my fixie wheels??? might start a new DH trend.


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## Mountain Cycle Shawn (Jan 19, 2004)

Wide rims on Steve Peat's bike.
Steve Peat's Custom-Painted Santa Cruz V10cc for Fort William - PIT BITS - Fort William World Cup - Mountain Biking Pictures - Vital MTB


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## NordieBoy (Sep 26, 2004)

Mountain Cycle Shawn said:


> Wide rims on Steve Peat's bike.
> Steve Peat's Custom-Painted Santa Cruz V10cc for Fort William - PIT BITS - Fort William World Cup - Mountain Biking Pictures - Vital MTB


What's the betting he won't use them in a WC race after this season though?


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## Guest (Jun 7, 2016)

FWIW...

Thread:








Tread:


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## Guest (Jun 7, 2016)

bob-o said:


> FWIW...
> 
> Thread:
> 
> Tread:


too cryptic for me.


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## jazzanova (Jun 1, 2008)

Mountain Cycle Shawn said:


> Wide rims on Steve Peat's bike.
> Steve Peat's Custom-Painted Santa Cruz V10cc for Fort William - PIT BITS - Fort William World Cup - Mountain Biking Pictures - Vital MTB


Anything new on this rims?


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## Mountain Cycle Shawn (Jan 19, 2004)

There doesn't need to be anything new here. Buy a set and start shredding!


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## oldranger (Apr 14, 2011)

*Lots of progress since originally starting this thread...*

But one thing seems to remain...25mm inner width rims like the DT EX471 still on DH bikes.


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## Lelandjt (Feb 22, 2008)

I thought most DHers are on 30mm now?


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## scooterman (Aug 10, 2004)

It's 2019 now and my road rims are almost as wide as my MTB rims. For me personally as a rider I have not found much benefit from running wider over 25mm ID MTB rims for my selection of tires.


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## jeremy3220 (Jul 5, 2017)

oldranger said:


> 2013 winning riders
> 
> Steve Smith - Easton Havoc 23mm
> Greg Minnaar - Enve DH 21mm (30mm external)
> Aaron Gwin - DT FR600 24.9mm


This thread didn't age well. Minnaar is on 31mm internal width rims now and Gwinn is on 30mm I believe.


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## oldranger (Apr 14, 2011)

jeremy3220 said:


> This thread didn't age well. Minnaar is on 31mm internal width rims now and Gwinn is on 30mm I believe.


In some ways, true. It's a boring topic now, but I had so much fun with MCS and Feather that I think about it each new year. The most important tire topic that's come up since I started it is clearly inserts (like Flat Tire Defender). Now that's a game-changer! Also new since the thread started is the 'Wide Trail' casing design from Maxxis. Designed for 30-35mm, those tires are some of the best support for the concerns I initially presented.

https://www.maxxis.com/wide-trail-wt-design

On the contrary, what has aged well is the EX471. Still seen on even the most progressive bike builds and fastest riders in the sport. Canyon Factory Racing and The latest 27/29 wheel prototype from Specialized (Finn Iles)

Many amateurs DHers I see are on 29-30mm inner width rims. It's a reflection of where the market has gone. And Stans new Flow Ex3 releases in March (580g and 29mm internal) will very likely end up my teams preferred rim with the current generation of Maxxis DH WT casing tires.


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## jeremy3220 (Jul 5, 2017)

oldranger said:


> Also new since the thread started is the 'Wide Trail' casing design from Maxxis. Designed for 30-35mm, those tires are some of the best support for the concerns I initially presented.


I have to give you credit on that one. Tires are now designed with wider rims in mind.


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## aerius (Nov 20, 2010)

jeremy3220 said:


> This thread didn't age well. Minnaar is on 31mm internal width rims now and Gwinn is on 30mm I believe.


Yes, and their results, especially in the case of Minnaar are well off their usual standards.


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## jeremy3220 (Jul 5, 2017)

aerius said:


> Yes, and their results, especially in the case of Minnaar are well off their usual standards.


Lol, I'm sure that's the reason. Gwin won the World Cup overall on those 30mm rims btw.


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## oldranger (Apr 14, 2011)

Speaking of what the pros are doing: a quick check of the 2018 UCI Top 10 (Points Standings) shows 4 of 10 riders were on the DT Swiss EX471 (inner width 25mm). The others were a smattering of 29-30 mm from different manufacturers. When I've been on track watching those guys over the past two years (Windrock Bike Park test sessions and races) either choice seems to be highly capable.

Again, I agree...this thread is an artifact of what was interesting (based on views and post count) years ago. My much my view at that time (typically a skeptic) was based on the local and regional hype where I live related to Industry Nine wheels and rims, which are ludicrously expensive and were pushing 'wide' at the time. Over the years...we've been doing just fine with Stans wheels w/Flow Ex and Mk3 rims. Our strong preference (pre-insert use) was the Flow Ex. Granted, the Mk3's made it easier to load inserts...but the durability wasn't there (we were destroying them too quickly). The Flow Ex3 should meet the needs of most amateurs at a damn good price point, with durability and room to easily manage Flat Tire Defender install/removal.

These days, the push to 29" wheels, inserts, and how those affect tire and rim design is more interesting. The Assegai on 30mm wide rims in a 29" diameter seems to have great promise on many trail conditions (other than wet clay). Look at what Maxxis is doing with lugs on that tire.


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## dirtrider76 (Sep 19, 2012)

I'm still rocking my EX471's and actually have a Aggressor WT on the rear which works great. The ex471 appears all over on winning bikes all over. Some riders like Rude run the 481(30mm)up front and 471(25mm) rear as well. At this point I think it really is preference and who is getting paid to run what. Fast guys are still gonna be fast on either.


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