# 30mm or 35mm rims for 2.6&quot; tires?



## Steel Calf (Feb 5, 2010)

With all major manufacturers now bringing 2.6" tires to the market what is the ideal rim width to pair them with?

There's numerous reports stating that the sidewalls of a Nobby Nic 2.6 already get too exposed on a 35mm rim, however Nobby Nic 2.8s often got paired with 40mm rims in the past.

I also heard reports that a narrower rim (which makes the tire a bit more rounded) gives the rider the option to lower rolling resistance by just running higher air pressures while on a wider rim that won't work anymore.

Now it looks like industry is not only downsizing Plus tires but rims as well for 2017. Most of Scotts Plus bikes come with 2.8 tires on 35mm rims.

Maxxis states that their new 2.6" Wide Trail tires are optimised for 35mm rims however they're already looking quite good on 25mm rims to me.

Enve states that wider rims have diminishing returns, at a certain point you only add weight without further increasing sidewall stability
Is wider always better? - ENVE Composites

That stays in sharp contrast to numerous rider reports that say that at very low pressures of 15-20psi the additional width of a rim does indeed make a difference in tire roll / tire squim

Stans Notubes is quite explicit with their recommendation:









The 29mm Flow for 2.35 - 2.8"
The 32mm Sentry for 2.5 - 3.0"
The 35mm Baron for 2.8 - 3.2"

what's your opinion? what would you go with in 2017 if you had 2.6" tires in mind?


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## kikoraa (Jul 25, 2011)

Lulz. Marketing man. Just try for yourself and see. I run 2.8 nics on a 30mm internal rim just fine. They grip and rip and I'm not the daintiest of riders. I huck a lot and descend aggressively. I run the front at 17 and the rear at 20. 

I'm sure I could get lower pressure with a 2.6. 

I do run 3.0 on another bike with 45mm internals. I will tell you I would probably rebuild those hubs with 40mm internal carbon hoops later this year. 

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## Redlands R&C (Dec 14, 2013)

I personally liked running 2.2-2.4" tires on 50mm external rims. Shape is a little odd, but for the riding I do it was perfect. Tire make/model also really come into play on rims that wide. 2.4 Ardents stayed right at 2.4 just with a slight rounding of the casing, same rim a 2.35 45Nrth Nicotine measured up to 2.65 with a great profile! But if I was to do it again, I would run 35mm


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## Smithhammer (Jul 18, 2015)

For a plus bike, I don't see any reason to go narrower than a 35mm rim (and even that is narrower than I prefer). 

Unless you plan on having multiple wheelsets, going all the way down to a 30mm rim is going to mean that your are limiting your options if/when you may want to run 'true' plus tires (2.8" - 3.0").


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## bdundee (Feb 4, 2008)

I ran 2.8 NN and RR's on 30I rims without issue for a summer, thought they were great. I would think to save sidewall exposure 30I rims for 2.6's would be optimal. That being said it goes against what Maxxis is saying.


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## RAKC Ind (Jan 27, 2017)

I don't see 2.6 tires as new, most 2.8 plus tires are actually 2.6, so by that their going to be nothing more than 2.4 labeled as 2.6. Tire industry has turned into a joke with tire sizes.

Now for the few "true to size" at the tread it's honestly hard to say a rim width because tire design plays a huge part. I don't want my sidewalls past my tread.

My 3.0 tires are on 45mm inner, can go a tad wider but I'm plenty happy where they are at. 2.8s I wouldn't go below 35mm inner but 40-45 is going to work out better for the desired effect. 2.6 is a waste below 35mm inner.


Biggest thing right now, welcome to more people drinking the marketing koolaid. It gets posted on an MTBR review that 2.6 is better because he doesn't have the legs and is very closed on types of riding. So now another big marketing push for the "next big scam".

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## Lovespicyfood (Aug 4, 2012)

Funny, I have a '16 Mason and there was quite a bit of talk lamenting the 32mm width rims...seems like the manufacturers haven't figured out any sort of standard yet...

I do have to say that I had 3.0 tires on it front and rear and the front tire washed out too easily imo because the profile was pretty rounded. Ended up putting the stock tires on the front that only measures ~2.4 and the bike feels a lot better.


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## jacksonlui (Aug 15, 2015)

Maxxis and stans cant agree. Maxxis tires cant even label their sizes cotrectly. Someome said maxxis widths are based on max psi, not sure if thats true. I would use these numbers as a rule of thumb. Seems no one really knows exactly what is what. Its all just a big swag

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## Smithhammer (Jul 18, 2015)

WTB knows what's up, in my experience. Their stated tire sizes are some of the most accurate I've seen. 

Most of the other brands? I'd love to have some of what they're smokin.'


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## bdundee (Feb 4, 2008)

Smithhammer said:


> Unless you plan on having multiple wheelsets, going all the way down to a 30mm rim is going to mean that your are limiting your options if/when you may want to run 'true' plus tires (2.8" - 3.0").


Agree 100% if you are getting a new wheelset.


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## Steel Calf (Feb 5, 2010)

I've tried Nobby Nics in sizes 2.6 / 2.8 / 3.0 and pretty quickly came to the conclusion that the 2.6" works best for me on a full suspension bike while 2.8" would be my favourite on a hardtail.

I remember a few years ago it was not uncommon to mount a 2.2 tire rear and a 2.4 front. With plus tires you could move one step further by mixing sizes and rim widths, like 2.8" tire on a 35mm rim front and a 2.6" tire on a 30mm rim rear.

Schwalbe 2.6 tires are bigger than their 2.35 counterparts as documented by b2b measurements so it's not just a marketing fad.


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## RAKC Ind (Jan 27, 2017)

That's the nice thing about options is there is plenty for everyone.

Mixing tire sizes is still done on plus bikes, works great for those who do it . Just a matter of preference.

Some companies get no where near their rated tire sizes, well documented especially on plus tires. Maxxis and others their tire sizes aren't accurate across the board. Wtb is a mixed bag. Schwalbe seems to be a bit better. Wtb 3.0 tires are true to size but their 2.8s range from 2.6-2.8 depending on the tire

But your not going to find a 2.6 tire that's not larger that it's 2.35/2.4 counterpart. But at the same time check the tread width on the smaller. Chances are the size is overrated.

I know nobby nics are at least close to size plus tires. I've seen a set of 2.8s first hand and my first question was "why did you put dirt bike tires on a mountain bike?". I couldn't imagine trying to pedal those things. 2.6 is probably a better place for those things lol, 2.8s the knobs are flipping huge. Rather ride my fat bike. Same traction (if not better), faster rolling 

Still a lot of it is marketing. Constantly throwing new stuff out there saying it's better than the other stuff. Instead of simply just offering the options so people have choices because skinny tires are dying 

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## jacksonlui (Aug 15, 2015)

Mixing 2.8 and 2.6 will slacken your bike. Someone quoted 0.5 inch difference in height.

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## alexbn921 (Mar 31, 2009)

I run 29x2.6 Nobby nic tires on 35mm internal rims. They measure 2.6 casing and 2.5 tread. They feel great and the shape is good, but I wish schwalbe would have spread the tread out to cover the sidewalls. I would recommend 30i as the sweet spot for rims right now. They will handle 2.35 to 2.8 and aren't that heavy.
I also have a Nobby Nic on the same 35i rim and it measures 2.4 tread and casing. Tire design needs to match rim width regardless of tire size. Maxxis is designing for 35mm which will most likely be the standard size for trail bikes going forward. Hopefully schwalbe will modify their 2.6 tires tread to mate better with a wider rim.
2.8 vs 2.6 schwalbe adds less than .2 inches to your bike after tire sag is accounted for. Same for 2.6 vs 2.35 about .15 inch added to the radius of the tire. They seem to get wider more than taller.


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## Steel Calf (Feb 5, 2010)

Smithhammer said:


> Unless you plan on having multiple wheelsets, going all the way down to a 30mm rim is going to mean that your are limiting your options if/when you may want to run 'true' plus tires (2.8" - 3.0").


I'm inclined to agree, but I'm considering a wheelset with 2.6" tires in mind. It should work perfectly with 65mm wide tires, everything else is an afterthought.

2.6" is the max size I can fit in the rear anyway and from my subjective experience so far I wouldn't go much wider in the front too, maybe 2.8" but that should be no issue on a 30mm rim according to numerious rider reports here.


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## Steel Calf (Feb 5, 2010)

alexbn921 said:


> I run 29x2.6 Nobby nic tires on 35mm internal rims.
> 
> I would recommend 30i as the sweet spot for rims right now. They will handle 2.35 to 2.8 and aren't that heavy.


thanks. I actually called Schwalbe and they said the 2.6 are designed with 30-40mm ID rims in mind. That would conclude a 35mm rim is the middle ground. However there are many riders like you reporting that 35mm may already be too wide, it is the question if that additional width can be felt and leveraged on the front wheel when running the 2.6 at super low pressures like ~15psi


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## alexbn921 (Mar 31, 2009)

I can compare Nobby nic 2.35 on 25i to 2.35/2.6 on 35i. It can be felt and the stability of the tire is improved. I feel that 30i is the tipping point for a 2.6 tire and while 35i will be more stable, we are talking about single digit %. Tire profile and tread pattern are more import. 35i gives a near perfect shape, but exposes the sidewalls too much. I think the 30 will have a similar profile/exposure as it's the tires design. Luckily we don't have a lot of tire killing rocks in Briones. I run 14-17psi depending on my ride and like the extra volume and support. Any preusser below 15 starts to squirm if you g it out.
10+ guys I ride with run the 35i rims with 2.35 to 2.5 maxxis/schwalbe tires. The enduro/DH tires have plenty of sidewall protection at 35.


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## JACKL (Sep 18, 2011)

I've run Hans Dampfs on i19, i25.5, and i35s. I19, floppy and unstable cornering. I25.5 worked well. No significant issues with tire flop. I35s: Handled better than i25.5s, but destroyed the sidewalls in 3 weeks. Didn't tear them, but they wore through the Snakeskin on sandstone rocks until the fabric was showing, and started leaking all over.

Now I have i35s and 29x2.6 Nobby Nics. Best tire I've ever ridden for it's combination of speed, rollover, and traction. But a few months in and the sidewalls are wearing out. I will try to post pics when I can. They have a ways to go, but the white threads of the sidewalls are beginning to show. The tires need one more row of knobs to be a great tire.

I am going to Whistler in July, and will probably end up running my Dirt Wizards. I don't want to run that much tire, but there isn't anything else available to run with 29er i35 rims. I don't want to do a wheel build, and I don't want to go back to my Flows and 2.35s either.

If I had it to do over I would probably have gone with i30s. I think eventually a non-plus 29er tire suitable for i35s will exist, but when I can't say.


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## Shredman69 (Apr 1, 2007)

Steel Calf said:


> With all major manufacturers now bringing 2.6" tires to the market what is the ideal rim width to pair them with?
> 
> There's numerous reports stating that the sidewalls of a Nobby Nic 2.6 already get too exposed on a 35mm rim, however Nobby Nic 2.8s often got paired with 40mm rims in the past.
> 
> ...


"I also heard reports that a narrower rim (which makes the tire a bit more rounded) gives the rider the option to lower rolling resistance by just running higher air pressures while on a wider rim that won't work anymore."

That's some misinformation right there. Higher pressure increases rolling resistance for off-road, not lower it. It doesn't matter the rim size for that. That's been shown in many studies including those by Schwalbe. Lower pressures can be run on higher volume tires AND wide rims due to the increased volume and increased sidewall support from the wide rims. High volume tires on skinney rims will have tire roll and burping issues from lack of sidewall support. I wouldn't run any tire 2.6 or bigger on any rim smaller than 32 internal. I currently have 2.8 Minions on 40 internal rims and they are perfect. I also have some 2.35 Schwalbe's, (Magic Mary and Hans Damf) on 32 internal rims and they are also perfect. On the 2.8's I run 14 & 17psi front and rear. On the 2.35's, I need to run about 20-25 front and rear. In back to back comparisons, the lower pressure 2.8's roll much faster and easier over rough terrain both uphill, downhill and flats than the smaller tires with higher pressures. So if I were you, and I could only fit a 2.6 in back, I would either run a 2.6 back and 2.8 front or both 2.6. Either way, I'd run them on 40 internal rims.


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## Steel Calf (Feb 5, 2010)

Shredman69 said:


> Higher pressure increases rolling resistance for off-road, not lower it. It doesn't matter the rim size for that.


I meant onroad with that one paragraph you cited, should've expressed myself more clearly. Because the narrower rim makes the tire more rounded the side knobs don't touch the ground anymore when "tuning" the tire with higher air pressure for extended onroad sections (not unusual on a long trip)

I think I'll settle with i30 rims after everything what has been said here, especially the reports about preworn sidewalls sound reasonable to me.

I'm on 24i rims right now, not sure if the additional 6mm (+25% width) justify the expense. Maybe a i35 rim front to give me the future option mounting a 2.8" tire and i30 back is a good mix as I'll run lower pressures front while being limited to a 2.6" in the rear


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## Dougal (Jan 23, 2004)

The schwable rolling resistance tests have some interesting fine print. They were done in soft surfaces. 

On hard surfaces more pressure does reduce rolling resistance. On very soft the opposite happens as you sink in further. 

It's terrain specific and can't be generalised.

Sent with 100% recycled electrons.


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## JACKL (Sep 18, 2011)

Dougal said:


> On hard surfaces more pressure does reduce rolling resistance. On very soft the opposite happens as you sink in further.


You meant hard smooth surfaces, correct? Because for example hard surface that is rocky can benefit from lower pressures.

I agree that the Schwalbe tests barely scratched the surface of the different scenarios that can occur during off-road biking. The good thing is that it opened people eyes to the fact that lower pressures than what we used to run can actually reduce rolling resistance in some cases.

It's a matter of balancing the different factors involved. Lower pressures increase losses from tire deformation, and at some point those losses will exceed the benefits lower pressure provide, like less ground deformation, and less energy used moving the bike and rider up and down over the terrain.

With smaller tires, that may have usually occurred at pressures lower that could be run without getting rim strikes. However now that tires are getting bigger, I think that more often it will be possible to run the pressure low enough that you'll be slower.

Agree it depends on the terrain. It's possible to have smooth hardpack that is similar to pavement. In which case I believe 30 or even 40 psi would roll faster than 20.


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## Steel Calf (Feb 5, 2010)

The 2017 Specialized Enduro comes with 29mm rims and 2.3 tires, I just saw it today and it doesn't look to be out of proportion. Going with wider tires should justify a slightly wider rim too IMO, a 32mm would be perfect.

I also saw a new Rocky Mountain Slayer today with Maxxis DHF 2.5WT on 30mm rims, the tire looks significantly more rounded on my bike with 24mm rims so Maxxis has a point here when saying "optimized for 35mm rims"


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## Dougal (Jan 23, 2004)

JACKL said:


> You meant hard smooth surfaces, correct? Because for example hard surface that is rocky can benefit from lower pressures.


Not necessarily hard and smooth. But yes it's complicated.

I ride hard terrain. But it's rocky (with gravel between the rocks) and not smooth. I run 2.35" tyres between 25-35psi. Basically when they hit around 25psi they feel soft and I pump them back up to 35.
I run rims up to 30mm wide.

I can't run much softer without risking damage. I also don't need to run softer as I've generally got as much traction as I need already and I have suspension sorted to deal with the rocks.

On loose over hard (gravel on hard base) higher pressure also gives lower rolling resistance. I ride a lot of this.

One big issue with wide and low pressure tyres that almost never gets heard is bouncing.
Big tyres at low pressure have a low natural frequency (slow bounce) which under fast riding makes the tyres rebound at the wrong time and plays havoc with the bike handling.
Slower riders don't have the issue. But it's why you don't see plus size tyres at races.

The only way around this is higher pressures. But when you run higher pressures on plus tyres then most of the tyre does nothing. So may as well run skinny.

Skinnier tyres have a faster natural frequency (faster bounce) which is never in the speed range that matters.


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## alexbn921 (Mar 31, 2009)

What the tipping point for this shift in frequency? How big can you go before it becomes a problem? Tire construction and local terrain factor into this too.
If you could design a perfect tire. What size and tread would it have?


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## Dougal (Jan 23, 2004)

alexbn921 said:


> What the tipping point for this shift in frequency? How big can you go before it becomes a problem? Tire construction and local terrain factor into this too.
> If you could design a perfect tire. What size and tread would it have?


It depends on the bike, the rider, the terrain, the speed, the pressure, the tyre construction etc etc.

The three things at play are stiffness (pressure, volume, shape) damping (tyre construction, rider motion, ground conditions) and driving frequency (speed, terrain etc).

There is no perfect anything. Our usages vary too much. Plus and Fat have a niche where they work very well.


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## Steel Calf (Feb 5, 2010)

From my experience wider tires have a very narrow range setting for optimal air pressure, too low and you'll kill the rims in no time, too high and the tires will act like a basketball and bounce you off the trail.

Wider rims have diminish returns in terms of added sidewall stability, however it's still up to debate which width is already too much and can't be leveraged anymore with lower air pressures just adding weight and exposed sidewalls prone to damage.


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## alexbn921 (Mar 31, 2009)

Dougal said:


> It depends on the bike, the rider, the terrain, the speed, the pressure, the tyre construction etc etc.
> 
> The three things at play are stiffness (pressure, volume, shape) damping (tyre construction, rider motion, ground conditions) and driving frequency (speed, terrain etc).
> 
> There is no perfect anything. Our usages vary too much. Plus and Fat have a niche where they work very well.


Agreed that it all factors in. I was asking you personally. Blank slate, what would you pick.
I'll go first. 2.6x29 with equal tread/sidewall sizing. Same size front to back. Medium trail tire front with decent protection around 800 grams. Faster shorter rear tire around 700 grams. Both need sidewall protection from the tread and casing. No race day only tires for me. I also don't need double or triple protection slow downhill tires.
Trail condition are very fast, hard over loose with some rock areas. Also needs to survive rockville, name says it all.
2.6 seem to me to have the perfect volume to grip ratio and is not in the bouncy balloon tire world.
4 years ago I said 2.6 was coming and I would build a bike around the tires when they came out. That time is now and I did.


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## Dougal (Jan 23, 2004)

alexbn921 said:


> Agreed that it all factors in. I was asking you personally. Blank slate, what would you pick.
> I'll go first. 2.6x29 with equal tread/sidewall sizing. Same size front to back. Medium trail tire front with decent protection around 800 grams. Faster shorter rear tire around 700 grams. Both need sidewall protection from the tread and casing. No race day only tires for me. I also don't need double or triple protection slow downhill tires.
> Trail condition are very fast, hard over loose with some rock areas. Also needs to survive rockville, name says it all.
> 2.6 seem to me to have the perfect volume to grip ratio and is not in the bouncy balloon tire world.
> 4 years ago I said 2.6 was coming and I would build a bike around the tires when they came out. That time is now and I did.


For me it's 26" 2.35-2.4". I need knobs extending past the carcass to save them being ripped open by rocks.
700-800g.
Maxxis Minion/Advantage/Aggressor are all pretty close to ideal.

I'm avoiding 27" until I get a boost frame and 29" isn't me.


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## jacksonlui (Aug 15, 2015)

Ive tried 2.8 rocket rons and rekons. The rocket rons were super fast rolling and light but i couldn't get over the bounciness. The rekons had more dampening and was closer to feel to the regular sized minions. I really like the rekons. I'd like to try the 2.6 but reports have said the diameter is 0.5 inches smaller which will drop my bb a bit too much as i already have a few pedal strikes. I like the extra traction up and down steep sections offered by the 2.8. It sucks climbing smooth fireroads and pavement, it feels like a boat anchor. However it does offer lower rolling resistance on climbs that are technical and rocky. With my 2.35 tires, rocks would push me back (hysteresis) but with the 2.8, it just conforms to it. 

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## alexbn921 (Mar 31, 2009)

jacksonlui said:


> Ive tried 2.8 rocket rons and rekons. The rocket rons were super fast rolling and light but i couldn't get over the bounciness. The rekons had more dampening and was closer to feel to the regular sized minions. I really like the rekons. I'd like to try the 2.6 but reports have said the diameter is 0.5 inches smaller which will drop my bb a bit too much as i already have a few pedal strikes. I like the extra traction up and down steep sections offered by the 2.8. It sucks climbing smooth fireroads and pavement, it feels like a boat anchor. However it does offer lower rolling resistance on climbs that are technical and rocky. With my 2.35 tires, rocks would push me back (hysteresis) but with the 2.8, it just conforms to it.
> 
> Sent from my SM-G930V using Tapatalk


Diameter should be .4 smaller with the radius and BB drop of .2 inches.


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## JACKL (Sep 18, 2011)

Dougal said:


> Not necessarily hard and smooth. But yes it's complicated.
> 
> I ride hard terrain. But it's rocky (with gravel between the rocks) and not smooth. I run 2.35" tyres between 25-35psi. Basically when they hit around 25psi they feel soft and I pump them back up to 35.
> I run rims up to 30mm wide.
> ...


Makes sense. I didn't even consider the bouncing aspect in regard to rolling resistance, but I did experience it when I tried 3.0s, and that is one reason they are no longer on the bike.


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## LyNx (Oct 26, 2004)

My take on PLUS tyres goes like this...2.8" on i35 rims run nice, keep the profile and only give a bit of tyre roll/squirm when you start to get down in the low PSI range at higher speeds, i40 would be preferable, but sidewalls then get very exposed, so it's a question of performance vs longevity. Right now my setup is i35 for 2.8" and i39 for 3.0" and it seems to work well. 
If I was building a wheelset specifically to run 2.6", I think I'd stick to i35, purely from a performance stand point, but the longevity f the tyres may suffer depending on your terrain. You could still run narrower tyres on them or wider tyres.

So, all these thoughts and feedback on PLUS tyres and what you're telling us is in fact you've never actually ridden any, is that correct?


RAKC Ind said:


> That's the nice thing about options is there is plenty for everyone.
> 
> Mixing tire sizes is still done on plus bikes, works great for those who do it . Just a matter of preference.
> 
> ...


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## LoneStar (Jun 17, 2004)

jacksonlui said:


> Mixing 2.8 and 2.6 will slacken your bike. Someone quoted 0.5 inch difference in height.


That wasn't my experience. The rollout on a new Rekon 2.6 was just a tad less than a Nobby Nic 2.8. I was pleasantly surprised. It may be a little less but it is nowhere near 1/2".

Edit: This got my curiosity up so I decided to measure it and see. This was with Stan Flow Mk3 rims.

Difference in radius between the Nobby Nic 2.8 and Rekon 2.6 was 7mm or .28". Hope this helps others like myself, who just couldn't get a 2.8 to work in the rear triangle of my existing bike.


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## Steel Calf (Feb 5, 2010)

Nobby Nic 27.5 2.6 on 35mm rims














































truth to be told the i35 rim looks a bit too wide for the 2.6" tire. Maybe stans was right?

I now decided for a 30mm rim rear / 35mm front because if I can ever leverage that added width it's the front tire where I run lower air pressure


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## vikb (Sep 7, 2008)

I'm happy with true width 2.4" tires on 35mm and 38mm rims. If I got some 2.6" tires I'd be okay with either of my existing rims.


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## JACKL (Sep 18, 2011)

The sidewall on my rear 29x2.6 Nic after a few months on i35s. They have a ways to go before they die, but clearly they will go in the trash with plenty of tread left. I knew this would happen going in, but unfortunately they are the only game in town for mid-plus 29er tires right now.


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## Shredman69 (Apr 1, 2007)

That's weird. Are they rubbing the inside of your chainstay or seatstay under hard cornering? And what does the tread look like?


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## lastchance (May 15, 2016)

I ride a 35mm rim with 3.0 Maxxis Chronicles, it's the absolute best rim/tire combo I've ever ever ever ridden. Marketing ********, getting you to buy into some new thing or buy something to replace something else because they make it sound like you "need" it.


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## JACKL (Sep 18, 2011)

Shredman69 said:


> That's weird. Are they rubbing the inside of your chainstay or seatstay under hard cornering? And what does the tread look like?


No, not even close to rubbing anything on the bike. That was 100% done by rocks. I'm not a geologist, but I would refer to the rocks where I like to ride as sandstone. If you are just riding dirt and roots, it would not be an issue. The tread is still pretty mint. There is just a small amount of wear and a little bit of knob erosion.

Same thing happened with 2.35 Dampfs on i35s, only much quicker. Tires looked like whitewalls in less than a month and started leaking. Dampfs on i25.5, same trails, no problems. 3.0 Dirt Wizards on i35s? No problem.


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## Steel Calf (Feb 5, 2010)

JACKL said:


> The sidewall on my rear 29x2.6 Nic
> View attachment 1139053


Comparing your picture with my picture above it looks as if the 29" version of the Nobby Nic 2.6" has even more exposed sideswalls than the 27.5" version on the same rim width, could it be that even though both tires share the same ETRTO width of 65mm the 29er tire is optimized for narrower rims?


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## Shredman69 (Apr 1, 2007)

Just for reference, Maxxis recommends 39i as a minimum for their 2.8. So a 2.6 from them should be on a 35i minimum.


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## azjonboy (Dec 21, 2006)

You need to read the study referenced on Scwalbe's website.

Lower pressures on MTB tires provide less deflection which translates into better traction and rollover.

Yes, there is a fine line that everyone has to find on their own for their terrain and tire choice.

I ride lots of rocks and sand on every ride. I run 2.4 tires tubeless at 18/19 front rigid. Rear tire at 22 tubeless. I run 29x3.0 on the front, rigid at 11 psi. Fantastic traction!

PS - You get bouncing from too much pressure, not too little. Too little increases squirm and chance of rolling off the rim.



Dougal said:


> Not necessarily hard and smooth. But yes it's complicated.
> 
> I ride hard terrain. But it's rocky (with gravel between the rocks) and not smooth. I run 2.35" tyres between 25-35psi. Basically when they hit around 25psi they feel soft and I pump them back up to 35.
> I run rims up to 30mm wide.
> ...


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## nitrousjunky (May 12, 2006)

Shredman69 said:


> Just for reference, Maxxis recommends 39i as a minimum for their 2.8. So a 2.6 from them should be on a 35i minimum.


I'm in kinda the same boat as you, in that I'm building up a frame that will only fit a true 2.6 max in the rear. Also thinking about running an i30-i32mm (definitely no bigger than i35mm) rear rim and i35-i40mm front rim.

FWIW though, I have been chatting with a Maxxis sales rep about the upcoming 29x2.6 Rekon. He told me that while it is designed for i35mm rim, it works really good on his i30mm rims as well.


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## Smithhammer (Jul 18, 2015)

nitrousjunky said:


> FWIW though, I have been chatting with a Maxxis sales rep about the upcoming 29x2.6 Rekon. He told me that while it is designed for i35mm rim, it works really good on his i30mm rims as well.


Probably because just like it's 'big' brother, The Rekon 2.6 won't actually measure 2.6" but more like 2.48."


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## nitrousjunky (May 12, 2006)

Smithhammer said:


> Probably because just like it's 'big' brother, The Rekon 2.6 won't actually measure 2.6" but more like 2.48."


Very well could be the case as I was told 65mm +/- 2mm, so 2.48" would be the lower end of that.

Looking at the pics of the 2.6 NN I've seen, I'd want that tire on an i30mm rim over i35mm rim for sure. They need to bring the knobs out farther on that tire!


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## Smithhammer (Jul 18, 2015)

nitrousjunky said:


> Very well could be the case as I was told 65mm +/- 2mm, so 2.48" would be the lower end of that.


Yeah, I wondered about that. In which case, we're not really even talking about a 'plus' tire anymore.

Maxxis makes great tires, but I don't understand why they (and others) continue to put out tires that don't measure up to their stated size.


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## funnyjr (Oct 31, 2009)

Smithhammer said:


> Yeah, I wondered about that. In which case, we're not really even talking about a 'plus' tire anymore.
> 
> Maxxis makes great tires, but I don't understand why they (and others) continue to put out tires that don't measure up to their stated size.


Cause realistically they wanna sell tires and they are aware that there are limited frames able to fit true 2.6 so better to error on side of caution and go narrower so fit more frames = more sales 
"Hey bro look, 2.6 fits (when truly only 2.48)...."
" cool dude, I'll go buy some "
" ya man I want some for my bike too"
(Says the next guy in line)

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## Dougal (Jan 23, 2004)

azjonboy said:


> You need to read the study referenced on Scwalbe's website.


Quite the opposite. You need to read the fine-print attached to that study on Schwables website. They tested tyres in extremely soft conditions. Which are the only ones where softer = lower rolling resistance.

It's all about ground deformation.



azjonboy said:


> PS - You get bouncing from too much pressure, not too little. Too little increases squirm and chance of rolling off the rim.


Nope. The natural frequency of a tyre is directly related to the pressure inside. Higher pressure = higher frequency.

It is low frequency bounce that sets uncontrollable motion into the bike and suspension. Which comes only from low pressure.


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## funnyjr (Oct 31, 2009)

Dougal said:


> Quite the opposite. You need to read the fine-print attached to that study on Schwables website. They tested tyres in extremely soft conditions. Which are the only ones where softer = lower rolling resistance.
> 
> Lower psi always felt better to me


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## Dougal (Jan 23, 2004)

funnyjr said:


> Dougal said:
> 
> 
> > Quite the opposite. You need to read the fine-print attached to that study on Schwables website. They tested tyres in extremely soft conditions. Which are the only ones where softer = lower rolling resistance.
> ...


If lower pressure did give lower rolling resistance then you'd see people winning road races with fat low pressure tyres.

But we don't. Because it doesn't. It's marketing bollocks.

Softer only lowers rolling resistance on very soft ground.


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## StumpyandhisBike (Jun 26, 2012)

But we're not riding our mountain bikes down the road are we?


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## Steel Calf (Feb 5, 2010)

Dougal said:


> Softer only lowers rolling resistance on very soft ground.


wrong, it reduces rolling resistance significantly over roots rocks and other uneven surfaces

XC racers do run pressures as low as possible but just high enough not to suffer any snakebites on their quite narrow tires

and they don't run plus tires because advantages in better traction and rollover are more than offset by the added interia


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## Smithhammer (Jul 18, 2015)

funnyjr said:


> Cause realistically they wanna sell tires and they are aware that there are limited frames able to fit true 2.6 so better to error on side of caution and go narrower so fit more frames = more sales
> "Hey bro look, 2.6 fits (when truly only 2.48)...."
> " cool dude, I'll go buy some "
> " ya man I want some for my bike too"
> (Says the next guy in line)


Possibly. But it's also the only reason I'm not buying a Rekon + right now. If it truly was a 2.8" tire I would have bought one yesterday. I also realize I'm probably in the minority, and that more people seem to want "almost plus" these days...._still,_ if it's a 2.6" tire, then call it a 2.6" tire.



Dougal said:


> If lower pressure did give lower rolling resistance then you'd see people winning road races with fat low pressure tyres.
> 
> But we don't. Because it doesn't. It's marketing bollocks.
> 
> Softer only lowers rolling resistance on very soft ground.


Wrong. On multiple levels.

For starters, equating what "wins road races" to lower rolling resistance in typical mountain bike scenarios is so far beyond apples and oranges as to not even be a remotely useful comparison.


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## alexbn921 (Mar 31, 2009)

Steel Calf said:


> wrong, it reduces rolling resistance significantly over roots rocks and other uneven surfaces
> 
> XC racers do run pressures as low as possible but just high enough not to suffer any snakebites on their quite narrow tires
> 
> and they don't run plus tires because advantages in better traction and rollover are more than offset by the added interia


This. 
There is a happy medium where rolling resistance and traction are maximized. Usually it's the lowest you can get away without rim strikes or tire squirm. Smooth course up to +5PSI might be better, but again your trading traction and comfort(energy) for speed in a different part of the course.
I run 2.6x29 on my trail bike with 16/18psi and 2.25/2.1x27.5 on my race bike at 22/26psi. You can vary pressure from your base settings to suit the terrain.

Tires should be marked and measured the same across all manufactures. Some/most like to advertise light weight and will undersized tires to hit that target. It's a shame that we have to play the how big is it really game.


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## jacksonlui (Aug 15, 2015)

Ive tried 16psi in my rekon 2.8s and it felt bouncy versus my normal 15psi. 1 psi makes a huge difference in feel for me.

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## bubba13 (Nov 30, 2009)

For a 2.6 tire I feel you could flip a coin to decide on 30i and 35i rims. If there was a possibility I might want to also run a 2.4 tire on the same wheel I would go 30i. Same goes for possibly running a 2.8 tire to a 35i rim. 

One of my current set ups in 27.5 has a 2.8 DHF front and 2.6 Rekon rear mounted on 35i rims. The 2.8 DHF measures 67mm casing and 69mm knobs at 15 psi. The 2.6 Rekon measures 65mm casing and 63mm knobs at 20 psi. Neither tire is far from listed size even at these riding pressures.

With a few months of riding this combo I find it works very well for PNW riding. The tires still handle like 2.4/5, but offer more damping/grip and both have a nice tire profile. If I were running 30i rims with these tires, I would probably have similar results, but with more air pressure on the narrower rims.


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## jtaylor996 (Jul 8, 2016)

Things are perfect with my NN 2.6" on i31.6 rims from light bicycle.


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## phride (Sep 14, 2015)

Dougal said:


> Quite the opposite. You need to read the fine-print attached to that study on Schwables website. They tested tyres in extremely soft conditions. Which are the only ones where softer = lower rolling resistance.
> 
> It's all about ground deformation.
> 
> ...


You guys need to start talking the same language. Low pressure for a 2.35" tire is high pressure for a 2.8' tire. The larger, lower pressure bigger tires are bouncier than the higher pressure smaller tire, but higher pressure in the bigger tires is bouncier than low pressure in the big tires, just like when you take some air out of a basketball.

I don't know what you are taking about with deflection frequencies. It seems to me more a matter of force generated by that deflection (amplitude) that make plus tires bouncy. The frequency might correlate over the scale that you're discussing (2.3-3.0 tires), but that doesn't ring true as a cause to me. Feel free to provide a physics lesson, if you've got this figured out, however.

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## daveypetey (May 16, 2012)

Crap. I am running 29mm Nox for my 29x2.6 Nobby Nic on my Wreckoning. Fail. :madman:


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## daveypetey (May 16, 2012)

Whoa! What PSI are you running to be getting that much flop with a 2.6???


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## RAKC Ind (Jan 27, 2017)

Guys are missing a few things here like bringing road into the debate. Even road is slowly going wider and lowering pressures. But it's not for the rolling resistance which is slightly increased. The comfort factor is proving reduce fatigue on the riders because truly how often is anything perfectly smooth. The decreased fatigue is allowing them to be overall faster.

But that is of course within limits, where not talking 2.0 tires here.

As for mountain biking there is more than pressure and surface that comes into play. Tread pattern effects A LOT.

2 tires that are identical except one has massive center knobs (like NNs or DHFs, especially in plus tire sizing) is going to benefit more from lower pressures with rolling resistance because the center knobs are more able to compress into the tire. So your rolling on something more round instead of a bunch of squared edges.

But something that is fast rolling (my example would be wtb ranger) but solid transition and side knobs, dropping the pressure to "just before tire flop and rim strikes" increases rolling resistance substantially unless on loose/soft terrain.

Simple physics:. Rubber for tires is a high friction material. The more contact that material has against the surface, the higher the rolling resistance because of the increased friction. Traction is friction.

When you add knobs to a tire that changes. The tire is no longer truly a round surface. So then becomes a balancing act based on the needs of the rider. Higher traction is higher rolling resistance. Bicycles don't break the laws of physics. However rider comfort reducing fatigue, able to maintain higher speeds to carry momentum due to increased traction are just a couple factors that come into play. Just like groomed hardpack vs loose/rough trails.

There is another thing:. Saying 1 psi on your pump makes a difference is completely bogus. Going from cool shade out onto a hot sunny trail will cause psi changes greater than that in a matter of minutes.

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## jacksonlui (Aug 15, 2015)

1 out of 15psi is about a 7% change. I can definitely feel the difference between 14, 15, 16 psi 

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## Dougal (Jan 23, 2004)

Smithhammer said:


> Wrong. On multiple levels.
> 
> For starters, equating what "wins road races" to lower rolling resistance in typical mountain bike scenarios is so far beyond apples and oranges as to not even be a remotely useful comparison.


Nope.

See the rolling resistance mechanics are identical between road and mountain. There is nothing that magically flips the physics around.

Rolling resistance is the deformation of the ground, tyre carcass and tread blocks. Deformation has to happen because you're continually flattening out a donut. A donut who's outer surface is not the neutral axis (so even more deformation).

Lower pressure in the tyre means more deformation of the tyre carcass and tread blocks with every movement in and out of the contact patch. Which means more rolling resistance.

The only thing that offsets that is ground deformation. If you are running on such soft ground that you are deforming the ground, only then can you reduce pressure and reduce rolling resistance.
But you are still experiencing much higher rolling resistance than firmer surfaces.

It's all about geometry. You're forcing a donut to conform to a flat surface. The more it has to deform to conform the more scrubbing occurs of tread entering and leaving the contact patch.

With very low pressures you also have scrubbing and movement throughout the contact patch.


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## Dougal (Jan 23, 2004)

Steel Calf said:


> wrong, it reduces rolling resistance significantly over roots rocks and other uneven surfaces


Got *any* data, physics, or indeed anything to backup that wild claim?

The best way to deal with rocks and roots is suspension. If you don't have suspension then you're introducing a massive compromise by trying to make a tyre do that job.



Steel Calf said:


> XC racers do run pressures as low as possible but just high enough not to suffer any snakebites on their quite narrow tires
> 
> and they don't run plus tires because advantages in better traction and rollover are more than offset by the added interia


XC racers do not run the lowest pressure possible.

They don't run plus tyres because they suck to pedal. The rolling resistance is much higher at all pressures.


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## Steel Calf (Feb 5, 2010)

Dougal said:


> See the rolling resistance mechanics are identical between road and mountain. There is nothing that magically flips the physics around.


Dougal, even you with your lecturing kind of way have to admit that a roadbike is ridden on the road while a mountainbike is ridden in the mountains.

No one argues that lower air pressure is increasing rolling resistance on a perfectly flat surface but even paved roads are not perfectly flat thus roadbikes have been shifting from 19-21C to slightly wider 23-25C tires for some time as rolling resistance is not everything if you bring reduced rider fatigue due to lesser bumps on the table.

I find it both striking and amusing that you always represent an opinion that's pretty much completely against common knowledge and common sense while at the same time desperately trying to back it up with pseudo facts as if you were clutching at a straw.

Make me wonder if you really believe what you say or maybe you're some weirdo who just wants provoke?


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## TheArmand (Jul 6, 2011)

Steel Calf, don't fret about 30 vs 35mm being optimum for a 2.6" tire. The reality of the industry today is we will never have tire width options of <1/2" ever again (1.9-2.4"). Don't ask yourself what will work best for a 2.6" tire, ask yourself if you would be more inclined to try 2.3-2.6" tires vs 2.6-3.0" tires down the line. Choose the rim width that will allow you to experiment with a greater range of tires that interest YOU (rider weight, style, and terrain) down the line. 

Of course, if you're loaded and building up wheelsets aint no thang than disregard everything I just said. 35mm gets my vote.


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## Steel Calf (Feb 5, 2010)

that's a good point I put a lot of thought into but on the one bike I'm upgrading right now I'm limited to 2.6 in the rear anyway and still have some 2.3 tires left while the Pike takes 2.6-2.8 tires so I went with a more solid EX511 30mm rear / XM521 35mm front

According to Enve a 35mm rim has diminishing returns with 2.6 tires so I only opted for this width in the front because of the lower air pressure the front tire is usually run and the option to try a 2.8

I agree that 35mm already looks a bit too wide for 2.6 tires, it greatly depends on the tire model too, I got the impression that the Rocket Ron 2.6 fits a 35mm rim much better than a Nobby Nic 2.6, maybe the Nobby Nics are coming from a narrower mold?


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## jacksonlui (Aug 15, 2015)

I thought it has been said that plus tires have lower rolling resistance because it conforms to irregularities in the road like rocks and roots rather than them pushing you back. I think it's called hysteresis. On a smooth paved surface, yes it sucks. My tires sound like a monster truck but its faster for me on more techy trails both up and down, you just need to be low enough to avoid being bouncy but not so low as to roll the tire or case your rim. Not a large window especially if youre a heavy rider.

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## Steel Calf (Feb 5, 2010)

Plus tires with their narrow carcasses are like an undamped air fork, the wider they are the narrower the optimal air pressure range. That's one of the reasons why the industry has scaled back the plus size to 2.6-2.8, it requires more experience and testing to find the optimal pressure with a 3.0" and pumping them up to hard can be outright dangerous on the trail.

After lots of testriding I'm finally receiving my own 3.0" hardtail next week looking forward for some first hand experience with the already obsolete tire width


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## RAKC Ind (Jan 27, 2017)

Not obsolete for me. I'm slowly buying extra tires (got 1 so far, but my current tires have 50 miles on them at) because of that.

My BB is already a tad lower than I would like with 3.0 tires on it, but specced with 2.8s (2.6 actual). 

So I'm making sure I have 3.0 tires while their cheap. Wtb ranger and trail boss 3.0 are true to size, fit my needs perfectly (probably a bit overkill with the trail boss). Being a big guy the 3.0 tires have a wider range of pressures I can run without being too bouncy. 

Now fat trees are another story. 3.8-4.0 I still have a good range. My 4.7s it gets really narrow between rolling resistance going to crap or being a handful when it gets rough. Which I why I have a plus bike. My right arm can't take trying to keep my fat bike under control in rough conditions for very long (multiple surgeries due to injuries over the years, latest was my elbow).

But wider is more confidence inspiring. Well the whole bike is. Carry speeds on trails that are more technical than anything local that I've only ridden once years ago than I did on my 29er on trails I know well. 

3.0 might not be your thing, but unless your a weight weenie xc racer, pick the right tires and you'll never go back to skinny mountain bikes 

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## Steel Calf (Feb 5, 2010)

I'm convinced that's why I'm switching to 2.6/2.8 on the full suspension and even bought a separate 3.0" hardtail but I'll probably settle with 2.8" on the hardtail and just increase fork travel to raise the bb


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## Dougal (Jan 23, 2004)

Steel Calf said:


> Dougal, even you with your lecturing kind of way have to admit that a roadbike is ridden on the road while a mountainbike is ridden in the mountains.


Except all mountainbikes also get ridden on the road and many road bikes get ridden in the mountains.

Plus, you know, all the usual physics applies equally to all.

The flatness (or lack thereof) of a surface does not invalidate any of the factors driving rolling resistance.



Steel Calf said:


> No one argues that lower air pressure is increasing rolling resistance on a perfectly flat surface but even paved roads are not perfectly flat thus roadbikes have been shifting from 19-21C to slightly wider 23-25C tires for some time as rolling resistance is not everything if you bring reduced rider fatigue due to lesser bumps on the table.


As you've just said. The roadies going wider are increasing rolling resistance. They're trading off human factors (fatigue).



Steel Calf said:


> I find it both striking and amusing that you always represent an opinion that's pretty much completely against common knowledge and common sense while at the same time desperately trying to back it up with pseudo facts as if you were clutching at a straw.
> 
> Make me wonder if you really believe what you say or maybe you're some weirdo who just wants provoke?


It's almost like "common knowledge" is just regurgitated marketing bollocks. With no basis in reality or physics.

I've backed all my claims with experience, examples, geometry and physical explanations. Just like drivetrain efficiency.

You've provided what?


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## Dougal (Jan 23, 2004)

jacksonlui said:


> I thought it has been said that plus tires have lower rolling resistance because it conforms to irregularities in the road like rocks and roots rather than them pushing you back. I think it's called hysteresis. On a smooth paved surface, yes it sucks. My tires sound like a monster truck but its faster for me on more techy trails both up and down, you just need to be low enough to avoid being bouncy but not so low as to roll the tire or case your rim. Not a large window especially if youre a heavy rider.
> 
> Sent from my SM-G930V using Tapatalk


Plus tyres have low rolling resistance compared to a fat bike. They all have higher rolling resistance than traditional widths.

What you're doing with air pressure is lowering it until the frequency drops low enough to feel like suspension. At that point they feel like they're not bucking (which you call bouncy). But if you ride them faster they'll quickly get out of control at that frequency.

Are you riding rigid or hardtail?

With suspension you run the tyres at a much higher frequency than the suspension. It avoids the instability of low frequency tyre bounce and the suspension does it's job taking out the bumps.


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## Dougal (Jan 23, 2004)

RAKC Ind said:


> Simple physics:. Rubber for tires is a high friction material. The more contact that material has against the surface, the higher the rolling resistance because of the increased friction. Traction is friction.


To expand on this bit. The issue we have with bike tyre width isn't solely the width. But the shape of the width.

Cars and trucks have belted tyres with a flat profile. They can lay the width of the tyre onto the road and not suffer much with rolling resistance. Because it's a cylinder and the face of the cylinder doesn't have to distort much to meet a road surface.

Bikes have donuts with rounded surfaces. As they meet a flat surface they have to distort the casing significantly. As you drop pressure further to lay more width (and length) they start to pucker in the centre of the contact patch.
You've then got tyre carcass and tread blocks entering and leaving the contact patch with markedly different radius and circumference. As they all meet the same flat surface the distortion is taken up with flexing knobs and carcass scuffing against the ground.

With lowering pressure it gets worse a lot more rapidly than an automotive tyre which is mostly only distorting the sidewalls.


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## jacksonlui (Aug 15, 2015)

I think your rolling resistance references apply only to smooth services. Doesnt really apply to techy mtb terrain. 

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## Dougal (Jan 23, 2004)

jacksonlui said:


> I think your rolling resistance references apply only to smooth services. Doesnt really apply to techy mtb terrain.
> 
> Sent from my SM-G930V using Tapatalk


They apply to everything.


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## LyNx (Oct 26, 2004)

If anyone wants to proves or disprove Dougals theories, it's very simple to do, just get a bike or bikes with various wheel setups and tyres size, find 2 hills, one road that's smooth and one trail that has a rough surface with at least 1cm tall rocks in it. Then just do a standing start on each hill, starting with high tyres pressures and reducing them as you do more runs, note the time it takes to roll "X" distance, spray paint a line on the trail so you can replicate the exact route if you want to be really nit picky :skep: 

I don't bother to argue semantics, wrong terminology is being used in these arguments, I know what my results would be.


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## Steel Calf (Feb 5, 2010)

Dougal said:


> I've backed all my claims with experience, examples, geometry and physical explanations. Just like drivetrain efficiency.


yes just like drivetrain efficiency...
but that thread was long lost to the front derailleur guys before you showed up with all that lecturing and enlightenment to give it the rest. It's useless to debate a guy who wants to convince others that "the earth is flat" and brings up all kinds of pseudo proof that's twisting reality and not related to the topic anymore.



Dougal said:


> Except all mountainbikes also get ridden on the road and many road bikes get ridden in the mountains.
> 
> Plus, you know, all the usual physics applies equally to all.
> 
> The flatness (or lack thereof) of a surface does not invalidate any of the factors driving rolling resistance.


And here we go again, Jesus Dougal don't screw up this thread too I mean it!


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## Suns_PSD (Dec 13, 2013)

I get the ideas about overall rolling resistance not increasing on a mountain bike when pressure is lowered. I've had some very experienced people, recently a Schwalbe tire rep, tell me to lower my pressure a bit (not nearly as low as many around here recommend however).
But when I gauge my overall speed and effort, I'm just faster on higher pressures on very bumpy terrain. 
I have a full suspension bike. Why should I rely on my tires absorbing bumps when my suspension should be doing this task?
I'm confused. 


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## LyNx (Oct 26, 2004)

A little thing called grip ut: Seriously, being fast and pinging off of every rock out of control is not goo, IMHO and are you really that fast if you're riding seriously chunky terrain with those "higher pressures". BTW, what do you call "high" pressures and what do you weigh? Tyres need to conform around obstacles to gain proper grip, try picking something up with your hand, but don't use your fingers to grab it, see how well that goes :idea:



Suns_PSD said:


> I get the ideas about overall rolling resistance not increasing on a mountain bike when pressure is lowered. I've had some very experienced people, recently a Schwalbe tire rep, tell me to lower my pressure a bit (not nearly as low as many around here recommend however).
> But when I gauge my overall speed and effort, I'm just faster on higher pressures on very bumpy terrain.
> *I have a full suspension bike. Why should I rely on my tires absorbing bumps when my suspension should be doing this task?*
> I'm confused.
> ...


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## jacksonlui (Aug 15, 2015)

Yeah. Im not really interested in arguing over tire pressures. If Doug thinks companies like Enve and others who have published reports that lower pressures have lower resistance on non smooth roads then thats fine, he can run skinny 1.9 tires at 100psi if that works for him. All I know is that bouncing off rocks wears me out.

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## Suns_PSD (Dec 13, 2013)

Could I see those studies? I'd like to see them but a quick Google search yielded nothing of value.

I do enjoy the greatly improved traction of lower psi, however it does not offset the additional perceived drag for me personally.

I'm not interested in arguing either and apt to defer to those with more experience. It's just my personal experience that higher pressure rolls better, and that's after running low pressures for quite some time. FYI lower pressures to me on 2.5 tires is like 22/ 24 and higher pressures is like 25/29. I weigh 180#, ride aggressively, but am not that talented or fit!

Thanks.


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## payze (May 19, 2014)

Having both 40i rim with 2.8/3.0 on a hardtail and a 30i rim with 2.6 on a fullsus, i can say the 30mm inner width is really enough for such small tyres, you don't need the extra rim width to deal with lower pressures because the 2.6 tyres aren't simply not plus tyres (small air volume).

However it depends where you are gonna put these rims, on a hardtail or a full sus?.

I'd go for 35i rim on a hardtail for maximizing traction, lower pressure and confort

For a full sus, better keep the rotating weigh low and go for a 30i rim

Some numbers: I ride the 2.6 NN at 1.25/1.30 bar on 30i rim whereas on the 2.8 and 3.0 NN I go as low as 0.8bar on the 40i rim (i have soft ground here, and i'm around 67kg)


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## Shredman69 (Apr 1, 2007)

Suns_PSD said:


> Could I see those studies? I'd like to see them but a quick Google search yielded nothing of value.
> 
> I do enjoy the greatly improved traction of lower psi, however it does not offset the additional perceived drag for me personally.
> 
> ...


Schwalbe did tests and articles about it. You can google that. It's been proven, lower pressures are MORE efficient over rough terrain. I'm guessing you are also running tubes with your pressures. That's too much pressure for tubless. I've already mentioned this, but I've personally done back to back rides on the same trails with 2.35 tires and plus size with lower pressures. The plus size was faster, had more traction with better rollover and more cushion up and down. I also coast downhill much faster than my riding buddies who are on skinnier tires with higher pressures, over soft AND hard terrain both on and off road. And lastly, more pressure equals more bounce. Someone else gave the basketball example and that's a good one. Pump it up to high pressure and it really bounces a lot. Lower the pressure and it doesn't bounce nearly as much.


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## Suns_PSD (Dec 13, 2013)

I Googled the Schwalbe test but it goes to a blank page. 

I run a Yeti 5.5 29er, on Kitsuma wheels that are 35mm ID (although more narrow CF wheels with 321 hubs are on the way), 2.5 Maxxis tires, full Avy suspension, and of course tubeless.

I rode some plus bikes and was a HUGE fan at first, but those tires and to an extent the wheels can not hold up under aggressive riding in my experience. They tear, rip, roll, burb, etc... with regularity. It is very confidence inspiring however and what I intend to purchase my wife in time (that's not a jab in any way).

I can certainly understand the low pressure idea, on a hard tail with no suspension to absorb bumps. I also understand it on plus tires because they have undamped rebound when inflated to normal psi's.

I get limited ride time but on one of these miserable hot TX summer days where rides aren't that fun anyways, I might just find a bumpy descent and just try different air pressures on my bike and try to see which rear pressure rolls the furthest for me. And then if I have the energy I guess I'd move to the front air pressure.

And I swear I'm not arguing, I'm just posting my personal experiences and trying to reach the best air pressure. I just want the least rolling resistance for my terrain.


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## jacksonlui (Aug 15, 2015)

Here are some articles which came up from google search. There is a nice picture on cushcore which shows hysteresis and how it saps forward momentum. The first youtube video by GNC is pretty good at explaining it and their tests was done in a lab. The other videos are from GMBN and BikeRadar.





https://www.schwalbetires.com/tech_info/rolling_resistance
Rolling Resistance Detail - CushCore


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## daveypetey (May 16, 2012)

Are 27.5+ wheels and tyres better than 29ers? - BikeRadar USA


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## Suns_PSD (Dec 13, 2013)

Some fun videos but most seemed to be comparisons between 27.5+ and 29ers.

I am interested in the argument for lower pressures to make my same bike/ tires faster. There are some interesting generalized points made but it just says "lower pressure = better" which frankly, just isn't true when it's expressed so vaguely. Is possibly 24 psi better than 27 psi on my rear tire? Possibly. But I guarantee you that 10 psi is way way slower.

I think I'm just going to try and do some testing myself once the dog days of summer kicks in and I'll report back.

~ take care


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## Dougal (Jan 23, 2004)

LyNx said:


> A little thing called grip ut: Seriously, being fast and pinging off of every rock out of control is not goo, IMHO and are you really that fast if you're riding seriously chunky terrain with those "higher pressures". BTW, what do you call "high" pressures and what do you weigh? Tyres need to conform around obstacles to gain proper grip, try picking something up with your hand, but don't use your fingers to grab it, see how well that goes :idea:


Why do you assume he has a problem with grip and tyre contact patch?

Getting "pinged" off rocks simply doesn't happen. Even without any suspension a good rider has no problem keeping a bike planted.
Every rock and obstacle that protrudes upwards places significant impact force on the tyre which provides immediate conformity and grip.

"Traction = friction factor * force applied" and all that.

I pump my tyres to 35psi and that turns many people into stammering disbelief. Usually people riding rigid carbon bikes on loamy trails.


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## Dougal (Jan 23, 2004)

Suns_PSD said:


> Could I see those studies? I'd like to see them but a quick Google search yielded nothing of value.


There was Schwable one, but suddenly it's almost impossible to find. They measured rolling resistance of tyres at various pressures to prove that lower pressure and higher volume gave less rolling resistance.

Then in the fine print they buried the fact the test was done on a soft field.

Yet the same test was parroted all over the internet by people who didn't read the fine print and believed it applied to all conditions ever.

TL;DR. Marketing bollocks.

As you've found, the physics and practice is very simple. Higher pressure gives less rolling resistance unless you start deforming the ground.


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## jacksonlui (Aug 15, 2015)

High pressure seems to work well for you guys. You should stick with it. Dont change if you're not convinced because it'll just mess with your head. 

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## Dougal (Jan 23, 2004)

jacksonlui said:


> Here are some articles which came up from google search. There is a nice picture on cushcore which shows hysteresis and how it saps forward momentum. The first youtube video by GNC is pretty good at explaining it and their tests was done in a lab. The other videos are from GMBN and BikeRadar.
> 
> 
> 
> ...


I'm not bothering with the videos. But the Schwalbe website says this:

[quote="Schwalbe]Off road it is exactly the reverse: 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 held back much less by the uneven surface.[/quote]

Their whole "offroad lower pressures means lower rolling resistance" claim is based totally on soft ground deformation. That's it. The rest is pure drivel and they provide nothing else to back their claim.

If you're not riding on soft ground (wet dirt, snow, sand etc) then it doesn't work like that. Their hard gravel claim is rubbish.


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## RAKC Ind (Jan 27, 2017)

Ok guys its very simple:

Laws of physics:. Dougal is pretty much right.

The rest of you are confusing rolling resistance to roll over and deflection.

Way too much bro science going on here versus actual fact. Sorry guys.

All of you saying lower pressures are faster because of lower rolling resistance are 100% wrong.

Your increasing roll over and decreasing deflection. That's what costs you speed when you ride anything that's not smooth.

Simple fact, take your mountain bike (I'll be nice and say put xc tires on it at least) and run you full low trail pressure and go ride 50 miles of payment only.

Then repeat with higher pressures.

Higher pressure will reduce the rolling resistance and you'll be faster and legs won't hate you.

Repeat on a trail. You'll find your tires deflect (bounce off of) anything rough on the trail, slowing you down. Low pressure you absorb the bumps and reduce the effects of the tires deflecting off rocks and roots.

2 completely different discussions, if discussing rolling resistance, lower pressure means more contact which means higher rolling resistance. DONE.

If discussing mountain bike low pressures and why it's faster, then your referring to changes in ROLL OVER AND DEFLECTION.

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## Miker J (Nov 4, 2003)

Everything in moderation.


All this "wider is better" mentality is getting carried away. IMO its being driven by the need for "increased stability" on a bike. Remember when a bike being "nimble" was a good thing? 

Tire durometer, tread pattern, and carcass makeup are the things we might want to pay more attention to.

While some can punch a few holes in the utility of the following premise, I think it carries more than a little weight.... Look at the tires and rims guys are racing on. There is not a lot of variation when it comes to rim/tire size. World Cup DH, Enduro, XC. These guys need traction, speed, and durability just like the rest of us. Only they push it harder and are quicker to expose weaknesses.


Personally I found going wide over rated. To prove it I've got some excellent conditions Derby carbon hoops in 275 x i35 and 29 x i30 looking for a good home.


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## jacksonlui (Aug 15, 2015)

Im just saying lower pressure and wider tires has been faster for me on my mountain bike on my trails.. Be it lower pressure, deflection, or whatever the terms are.

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## Shredman69 (Apr 1, 2007)

jacksonlui said:


> Im just saying lower pressure and wider tires has been faster for me on my mountain bike on my trails.. Be it lower pressure, deflection, or whatever the terms are.
> 
> Sent from my SM-G930V using Tapatalk


Same for me. Must be an illusion then.:thumbsup:


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## Shredman69 (Apr 1, 2007)

Miker J said:


> Everything in moderation.
> 
> All this "wider is better" mentality is getting carried away. IMO its being driven by the need for "increased stability" on a bike. Remember when a bike being "nimble" was a good thing?


The "increased stability" from wide rims refers to sidewall stability, not handling stability. As in less tire roll or burping with big tires on skinney rims and low pressures.


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## Shredman69 (Apr 1, 2007)

Dougal said:


> I'm not bothering with the videos. But the Schwalbe website says this:
> 
> Their whole "offroad lower pressures means lower rolling resistance" claim is based totally on soft ground deformation. That's it. The rest is pure drivel and they provide nothing else to back their claim.
> 
> If you're not riding on soft ground (wet dirt, snow, sand etc) then it doesn't work like that. Their hard gravel claim is rubbish.


It's not rubbish. It's really pretty simple. When a tire with lower pressure rolls over soft terrain or gravel, or rocks or roots, the tire conforms to the trail and rides over it without sinking in, (more efficient, faster and easier). When you take a skinnier tire with higher pressure, it will sink in to the soft terrain or gravel, (less efficient, more work and slower). This is the same reason 4 wheel off-road vehicles let the air out of their tires when going in the sand dunes, so they don't sink into the sand and get stuck. They stay on top of the sand. Or rock crawling, the tire conforms to the trail and hooks up better and rolls over obstacles better with lower pressure. It also absorbs small trail chatter better, hard tail or full suspension doesn't matter. I currently run 26+ on a 180mm Uzzi, hard and fast over roots, rocks, drops and jumps. My back to back runs with smaller tires with higher pressures and the plus size with lower pressure, Plus size with lower pressure wins everywhere. But if running higher pressures works for you, that's all that matters.


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## jacksonlui (Aug 15, 2015)

Yeah. Im a sucker for marketing. If they say its faster, i wanna try it for myself. I dont care about semantics. In the end, what us faster and what is more fun and what do you want out of it. For me, wider rims, lower pressure is faster which means more fun. More traction, more safe, push harder, etc. There's a sweetspot window for everyone. Not everyone can ride a big tire with low pressure because truly aggressive riders cant get low enough pressure without being bouncy and they typically need DD casing. 

Anyways, digressing from original topic.

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## Dougal (Jan 23, 2004)

Shredman69 said:


> It's not rubbish. It's really pretty simple. When a tire with lower pressure rolls over soft terrain or gravel, or rocks or roots, the tire conforms to the trail and rides over it without sinking in, (more efficient, faster and easier). When you take a skinnier tire with higher pressure, it will sink in to the soft terrain or gravel, (less efficient, more work and slower). This is the same reason 4 wheel off-road vehicles let the air out of their tires when going in the sand dunes, so they don't sink into the sand and get stuck. They stay on top of the sand. Or rock crawling, the tire conforms to the trail and hooks up better and rolls over obstacles better with lower pressure. It also absorbs small trail chatter better, hard tail or full suspension doesn't matter. I currently run 26+ on a 180mm Uzzi, hard and fast over roots, rocks, drops and jumps. My back to back runs with smaller tires with higher pressures and the plus size with lower pressure, Plus size with lower pressure wins everywhere. But if running higher pressures works for you, that's all that matters.


If you read my earlier posts here in this thread, I've been completely consistent with the soft ground issue.

Schwalbe (and others) are trying to extend the soft ground argument to cover all moutain bike riding.
Which is complete bollocks.

You do realise that running an Uzzi downhill faster has no relationship to rolling resistance?

It's also worth noting that the fastest DH riders aren't using plus size. It's almost like DH went through all this size related drama 15 years ago and settled on ~2.5". It was 2002 I had a 3.0 Gazzalodi to play with.

Rock crawlers don't care about rolling resistance either.


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## Miker J (Nov 4, 2003)

Shredman69 said:


> The "increased stability" from wide rims refers to sidewall stability, not handling stability. As in less tire roll or burping with big tires on skinney rims and low pressures.


Refers to both.

People ride chubby tires because they provide a more stable feeling ride. There may be other reasons too.

Bigger rims/tires with more grip, and slower rolling add a feeling of stability to the bike. It becomes less twitchy or less nimble. Many riders who are after that feel gravitate toward chubby tires.

That is ok if that suits one's style.

If I have to pedal, for trail/AM use, I prefer a quick feeling bike. So, unless I'm on a rigid rig most tires beyond 2.4" feel too stable, or less nimble/quick to me.

On my DH bike, which I run primarily at my local DH, which is old school, slick, chunky, wet, roots, rocky, ledgy, steep, and fast, I want to get more stability out of my bike. So, I run 2.5" Magic Mary DH tires - big tires that dwarf my 2.5" DH Minions.

3.0 Gazzi - would not fit on the rear of my Bullit, but lived up front on my Super T for a long time.


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## Shredman69 (Apr 1, 2007)

Nope. Geometry affects stability. Head angle, chainstay length and wheelbase as well as wheel/tire diameter.


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## Smithhammer (Jul 18, 2015)

Seeking more stability has nothing to do with why I choose to ride plus. 

We can debate the semantics of rolling resistance if need be. But the reality in my experience is that a plus tire with lower pressure is often faster on the same trails than the same tire with higher pressure, or a skinnier tire with higher pressure. I honestly couldn't give a rat's ass about the academics.


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## alexbn921 (Mar 31, 2009)

Let's take a rigid bike with a plus tire. There will be a sweet spot where the tire has the lowest rolling resistance on choppy ground. This will be lower than on smooth terrain.
When the tire can absorb an impact rather than rebounding off, it saves energy. This conforming to rocks and roots requires a lower psi.

I run my tires until they start to squirm and then add 2-4 psi depending on the race or ride. This gives me a good ride quality with maximum traction and close to optimal rolling resistance.
I do the same thing on my road bike. The biggest tires that will fit, running at the lowest pressure I can comfortable get away with. 28mm @ 70 front/ 75 rear.

My local spot has unrelenting cow hoof up fire roads and I'll take anything I can get to reduce the chop chop chop.


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## Miker J (Nov 4, 2003)

Shredman69 said:


> Nope. Geometry affects stability. Head angle, chainstay length and wheelbase as well as wheel/tire diameter.


Many things effect how stable a bike feels, especially geometry. Completely agree.

So does wheel size, and I think that is why many riders like chubby tires, whether consciously or sub-consciously.

Smash into a downhill rock garden at high speed on the same bike.

Once set up with 2.5" tires run at proper psi.

Next on the same bike with 2.1" tires run at proper psi.

My guess most riders would say the bike with 2.5" tires would feel more stable.

My other guess is I may have a broader definition of "stable".

So, this may be a matter of semantics.

I'm always up for semantics.


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## Dougal (Jan 23, 2004)

alexbn921 said:


> When the tire can absorb an impact rather than rebounding off, it saves energy.


How does that save the rider energy?


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## RAKC Ind (Jan 27, 2017)

Actually it's very true because of tire deflection. Roll up on a square edge and a rock hard tire. It can stop you almost dead in your tracks because of the tire rebounding hard in the opposite direction. Not lower the pressure and the tire can deform and roll over it much easier. Meaning you carry more speed over the obstacle vs fighting back against the tires trying to literally bounce backwards away from the obstacle. Or smaller stuff simply bouncing upwards meaning you still have to fight it. Go ride a rigid fat bike on rough trails, that will bring you up to speed real fast lol. Good luck keeping control for long before arms and legs fatigue out if your pressure is too high. It'll bounce you all over the place. Same rules apply for skinny tires, just less noticeable for short term, adds up the longer the distance. 

I put that I more simple terms for the average readers fyi. I also have a road bike, plus bike and a fat bike. Become very well versed in this.

Also was just discussed about road riders going wider and lowering pressures to reduce fatigue. Fatigue is caused by over expending your energy. Save that energy, reduce fatigue.

actually a heavily discussed and researched point of why you drop tire pressure on mountain bikes.

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## jacksonlui (Aug 15, 2015)

3 pages. The horse is dead. 

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## Dougal (Jan 23, 2004)

RAKC Ind said:


> Actually it's very true because of tire deflection. Roll up on a square edge and a rock hard tire. It can stop you almost dead in your tracks because of the tire rebounding hard in the opposite direction. Not lower the pressure and the tire can deform and roll over it much easier. Meaning you carry more speed over the obstacle vs fighting back against the tires trying to literally bounce backwards away from the obstacle. Or smaller stuff simply bouncing upwards meaning you still have to fight it. Go ride a rigid fat bike on rough trails, that will bring you up to speed real fast lol. Good luck keeping control for long before arms and legs fatigue out if your pressure is too high. It'll bounce you all over the place. Same rules apply for skinny tires, just less noticeable for short term, adds up the longer the distance.


Remember force =/= energy. Energy is force*distance. 
A force spike from a tyre striking a rock (in a direction that opposes the corner of the rock) is not a significant converter of energy to any other means.

A softer tyre that deforms more isn't reducing that energy, it is simply spreading the impact over distance and time. Total energy is exactly the same.
The difference is between the energy being damped out in the tyre carcass or not.

I don't ride rigid any more. The trails where I ride are too rough and rocky. Your eyeballs buzz up and down so much that the trail becomes a blur.
Yet these same rough and rocky trails are where I run tyres at 35psi. I use suspension to deal with the rocks and roots.



RAKC Ind said:


> I put that I more simple terms for the average readers fyi. I also have a road bike, plus bike and a fat bike. Become very well versed in this.
> 
> Also was just discussed about road riders going wider and lowering pressures to reduce fatigue. Fatigue is caused by over expending your energy. Save that energy, reduce fatigue.
> 
> ...


Fatigue and rider comfort are interesting topics. But they're not related to energy lost via rolling resistance.

A firmer tyre on good suspension gives far less fatigue and rolling resistance than a bigger and softer tyre on rigid or poor suspension.


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## Steel Calf (Feb 5, 2010)

Dougal said:


> Fatigue and rider comfort are interesting topics. But they're not related to energy lost via rolling resistance.
> 
> A firmer tyre on good suspension gives far less fatigue and rolling resistance than a bigger and softer tyre on rigid or poor suspension.


Sorry Dougal but that's just plain wrong.
Higher rolling resistance requires more power input from the rider to compensate for the energy loss while more bumps due to higher tire pressure lead to increased rider fatigue as well so sure they're all related.

No matter how good your suspension is it cannot offset an overly firm 35psi tire in rocky terrain. It is absurd to trade one thing for the other, you'd want to set up both the best way possible.


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## jacksonlui (Aug 15, 2015)

If high pressure is the answer , then why stop at 35psi. Why not pump it up to the max psi written on the tire? 

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## RAKC Ind (Jan 27, 2017)

Dougal 

I have to agree with the other guys, your missing a lot of the details and facts here man. First saying the force spike against a rock is insignificant I think you need to spend some time researching. You ramming a tire that's carrying 150lbs plus bike weight into a rock. And that is done across a thin impact zone the width of the tire. So what's the impact force of 180lbs traveling at 15mph? Now the tire has enough energy to rebound all that weight.

Physics: every action has an equal and opposite reaction.

Now your suspension and you are battling those forces pushing back against you on every rock you hit. Calling it insignificant says you truly don't have an understanding of the laws of physics or how a tire works.

I've ridden FS, have a rigid fact bike and have a plus hard tail. Though good suspension does great things, lowering tire pressures is basically a requirement.


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## Dougal (Jan 23, 2004)

Steel Calf said:


> Sorry Dougal but that's just plain wrong.
> Higher rolling resistance requires more power input from the rider to compensate for the energy loss while more bumps due to higher tire pressure lead to increased rider fatigue as well so sure they're all related.


Your run-on sentence has two entirely different concepts mixed up.



Steel Calf said:


> No matter how good your suspension is it cannot offset an overly firm 35psi tire in rocky terrain. It is absurd to trade one thing for the other, you'd want to set up both the best way possible.


Those claiming things are impossible should not interrupt those currently doing it.


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## Dougal (Jan 23, 2004)

jacksonlui said:


> If high pressure is the answer , then why stop at 35psi. Why not pump it up to the max psi written on the tire?
> 
> Sent from my SM-G930V using Tapatalk


Because extremes are seldom helpful. They often led to the straw-man arguments.

The answer is, because 35psi still gives the blend of traction, impact resistance and rolling resistance that works for my riding.

Going to 60-80 psi would roughly half tyre contact patch, greatly reducing traction and giving only minor improvement in rolling resistance.

It also chews out the middle of the tyres.


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## Dougal (Jan 23, 2004)

RAKC Ind said:


> Dougal
> 
> I have to agree with the other guys, your missing a lot of the details and facts here man. First saying the force spike against a rock is insignificant I think you need to spend some time researching. You ramming a tire that's carrying 150lbs plus bike weight into a rock. And that is done across a thin impact zone the width of the tire. So what's the impact force of 180lbs traveling at 15mph? Now the tire has enough energy to rebound all that weight.


I'm talking about energy loss and you're talking about force. They aren't the same thing which is why you're still not understanding my argument.

I've been riding rim destroying rock trails for ~25 years now. I'm quite familiar with the practice and the theory. There was no suspension when I started riding. It took 10 years before decent suspension with enough travel was even available.

When a wheel rolls over a rock or root, it loses energy and speed on the way up, but gains that energy back on the way down the other side.
The two energy losses are deformation of the tyre and if the wheel loses contact with the ground on the back side (no ramp down).

Do you agree that far or no?



RAKC Ind said:


> Physics: every action has an equal and opposite reaction.
> 
> Now your suspension and you are battling those forces pushing back against you on every rock you hit. Calling it insignificant says you truly don't have an understanding of the laws of physics or how a tire works.
> 
> ...


I'm not calling the force insignificant. I'm calling the energy (force x displacement) insignificant.
Completely different things.

You're talking about "lowering tire pressure". But that's a relative measure and relative to what?
Lowering when someone is at 45psi is very different to lowering when someone is at 15psi.

Fat tyres with low pressure and fast speeds on rocky terrain are an unholy and unstable mess. The tyre rebounds uncontrollably at all the wrong times.
Which is why narrower tyres and real suspension are required to be competitive at Enduro and DH racing. Especially on rocky terrain.


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## Steel Calf (Feb 5, 2010)

Dougal said:


> When a wheel rolls over a rock or root, it loses energy and speed on the way up, but gains that energy back on the way down the other side.


hahaha hilarious!!

What you forgot to mention is that this "Dougal effect" only works with tire pressures @35psi, a soft tire @18psi will deform too much on that rock and the possible energy gain is thus lost

do you agree so far?


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## Dougal (Jan 23, 2004)

Steel Calf said:


> hahaha hilarious!!
> 
> What you forgot to mention is that this "Dougal effect" only works with tire pressures @35psi, a soft tire @18psi will deform too much on that rock and the possible energy gain is thus lost
> 
> do you agree so far?


No.


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## Steel Calf (Feb 5, 2010)

too bad. Looks like I'll have to pump up my tires @35psi and make it a day!


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## jacksonlui (Aug 15, 2015)

Sometimes its more fun if opamps are ideal and the world is flat. We get to choose our own reality. Its better that way.

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## jacksonlui (Aug 15, 2015)

Force and rolling resistance of course matters and works hand in hand. We care about how much energy we require to cover a certain distance. The energy required is the force we must apply to overcome resistance or something which resists us moving forward. Be it contact resistance from the ground, gravity, or anything that pushes back like a rock. Imagine pushing a shopping cart. The tires are hard and when you push it, there's contact resistance but there is more drag if your tire is much softer. Imagine hitting a low curb or cobble stones with the hard tire, it requires more force than a soft tire to get over. 

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## RAKC Ind (Jan 27, 2017)

Dougal, I agree to a point. It's not being "lost or gained". It's transfered. 

Yes 45 psi vs 15 psi are very different things. Very right there. And there is a tipping get point in any tire where benefits are overcome by rolling resistance and other issues.

Yes now to be "competitive" good suspension is needed. But a fat bike is far from unrideable of rough terrain. High tire pressure is the worst thing you can do on wide tires. Lower pressures control the rebound of the tire. And setting a fat bike tire down low (takes some experimenting to get right) and the bouncing issues are resolved rather well. We have a massive fat bike following here and I'll listen to the guys that have been riding them since the first pugs came out long before anything posted here.

And no I'm not talking about 2 different things, I talking about effects of one on the other. The actions of a tires under forces exerted by the trail and how it effect the riders energy levels. 

Sorry but 99% of riders don't ride with high end suspension. Majority ride hardtail. And even full suspension bikes there are still benefits that out weigh the draw backs by far when decreasing tire pressures vs running the max pressures of tires.

Difference between you and some others here (some are just being rude or trolls) is we know what works and doesn't. Years riding matters little honestly. I tried riding your way and it's miserable and SLOW. Ride our way with appropriate pressures (only time I say the pressures you ride is when I started riding at over 300lbs, I had no choice) and it's more enjoyable and we are faster than we are when we run "higher" pressures.

If I was riding 2.0 tires then ya 35 psi would make sense, I'm a big guy. 3.0 tires I run a little over half that.

The problem is your stuck in absolutes and old thinking. Lower pressures (tire size pending) is faster and more comfortable because it costs the rider less of their energy and allows carrying higher speeds which means momentum carried through obstacles. Again saving the riders energy.

I am talking how these changes effect riders, you stuck on the laboratory physics of the bike itself. Have to let go of that to realize the difference. Not or ever have meant any disrespect just trying to help you see past lab tests and old school thinking.

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## Dougal (Jan 23, 2004)

RAKC Ind said:


> Dougal, I agree to a point. It's not being "lost or gained". It's transfered.
> 
> Yes 45 psi vs 15 psi are very different things. Very right there. And there is a tipping get point in any tire where benefits are overcome by rolling resistance and other issues.
> 
> ...


So you think I'm all lab theory and my experience and observations don't count.

Here's a very simple challenge to find the lowest rolling resistance: Find me all the bike races won by plus or fat tyres.

I'll wait.

BTW Where I live and ride it's not 99% hardtail. It's over 90% FS. If you have 99% HT then you haven't got rough terrain. If you think a fatbike doesn't have uncontrolled bounce then you're not riding fast enough. Most fatbikes can't do 30km/h.


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## jacksonlui (Aug 15, 2015)

That has nothing to do with our discussion and isnt relevant. Racers cant run low pressures because they are too aggressive and plus tire casings are too weak. 95% of us arent at that skill level and running low pressure is an option which provides better traction and requires less energy. Low psi isnt an option for everyone and if it is, it offers overall lower effective resistance relative to power required.

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## Dougal (Jan 23, 2004)

jacksonlui said:


> That has nothing to do with our discussion and isnt relevant.


Yes it is. It's the very crux of the "pressure vs size vs rolling resistance" debate.

In every single race format (except sand and snow) the skinny tyres (at higher pressure) win. They provide enough traction, better control and lower rolling resistance.

You're done here.


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## Guest (Jun 4, 2017)

just wow.


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## alexbn921 (Mar 31, 2009)

Dougal said:


> Yes it is. It's the very crux of the "pressure vs size vs rolling resistance" debate.
> 
> In every single race format (except sand and snow) the skinny tyres (at higher pressure) win. They provide enough traction, better control and lower rolling resistance.
> 
> You're done here.


Dude you need to take a chill pill. You like high pressure tires we all get it.

I on the other hand am running 2.6 tires and find that the sweet spot is 16-18 front. Traction is off the chart and when I hit a bump or rock the tire deflects instead of moving the whole mass of the bike and rider. This saves me energy that I have to turn around and use to propel the bigger heavier tire. The grip, comfort and extra speed in the chunk is a net advantage for me. I have zero problems with tire rebound or squirm.

I'm sure you will say that I'm not fast enough to experience the negative effects, but I ride with pro enduro riders and can beat them on some segments.

Your style may not work with whatever we are talking about but that doesn't mean it's not true. Just my personal opinion gathered over 25 year of riding mountain, road and touring. Oh and add in 10 years car racing with a local championship to that too.


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## lastchance (May 15, 2016)

This thread is intense. 

I like 3.0 tires on 35mm rims at 18psi, no more, no less. Add in 140mm of travel in the front of a steel hardtail... MAGIC.


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## jacksonlui (Aug 15, 2015)

Its cool that we all can have opinions and i respect that. For all I know I'm wrong. The world is flat and we all live in a simulation. However, we've all had a chance to provide our opinions eventhough not one person agrees with Dougal I still respect his opinion. In the end, what you truly believe in is the only truth.

Dont look at pros to set the trend. There are not enough tire options for them and it seems the industry are going to converge on 2.6 tires. I'm willing to bet pros will use 2.6 in the next year or so. They are already using 2.5 so you can surmise that the trend is wider and lower psi, definitely not skinnier or higher psi. Remember when everyone was against 29ers and we saw noone using one in races? Look at the trend now and how many 29ers were used in the enduro. So saying because the pros dont use it doesnt mean its wrong, its just being short sighted.

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## Dougal (Jan 23, 2004)

alexbn921 said:


> Dude you need to take a chill pill. You like high pressure tires we all get it.
> 
> I on the other hand am running 2.6 tires and find that the sweet spot is 16-18 front. *Traction is off the chart and when I hit a bump or rock the tire deflects instead of moving the whole mass of the bike and rider.* This saves me energy that I have to turn around and use to propel the bigger heavier tire. The grip, comfort and extra speed in the chunk is a net advantage for me. I have zero problems with tire rebound or squirm.
> 
> ...


2.6" isn't exactly plus or fat. It's a marketing reboot of a size that's been popular for at least 15 years. But what is interesting is your claim about them sucking up rocks. In bold above

A 2.6" tyre when ridden has at the most 2 inches of compression before the carcass is slammed against the rim. 2" ain't much of a rock.
The tyre also can't suck up any rock without feeding impact through the fork to the frame and rider. 
To compress the tyre takes force, that force feeds up into the bike to accelerate everything upwards. F = M*A

So you can beat pro Enduro riders on some segments? How much suspension are you running? Most enduro riders are on 160-180mm of travel. 
With 6-7" of suspension the 2" of tyre squirm on every rock becomes a handicap. Not an asset.

Basically none of it works the way you say it does.

Did you run low pressure balloon tyres on your race cars?


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## Steel Calf (Feb 5, 2010)

Dougal said:


> The tyre also can't suck up any rock without feeding impact through the fork to the frame and rider.


neither can the suspension, there's always some feedback.

A 2.6" tire has more volume than a 2.2" and thus will suck up more bumps, this advantage stays no matter how good your suspension is

Furthermore the 2.6" tire will conform better to terrain and thus provide better traction, am I (again) pointing out the obvious here?

I don't know what your motivation is to constantly argue in every thread against common knowledge but how can you debate a guy who's insisting the world is flat?


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## alexbn921 (Mar 31, 2009)

Dougal said:


> 2.6" isn't exactly plus or fat. It's a marketing reboot of a size that's been popular for at least 15 years. But what is interesting is your claim about them sucking up rocks. In bold above
> 
> A 2.6" tyre when ridden has at the most 2 inches of compression before the carcass is slammed against the rim. 2" ain't much of a rock.
> The tyre also can't suck up any rock without feeding impact through the fork to the frame and rider.
> ...


I have been waiting for over 4 years for a decent 29x2.6, so I could bike a new bike around it. They haven't been around for 15 years.

I ran pneumatic tires. Getting the pressure even 1 psi off made a difference in grip. 3 psi off optimal and you might as well just go home because you wouldn't be competitive.
I run 130mm to 110mm depending on the bike, so the 55mm of tire is half my suspension. That's not insignificant.
The tire have a different spring rate than the shock. When you hit a 1 inch rocks/chatter on the trail you only have to move the mass of the tire contact patch up out of the way, instead on the whole bike. The energy is much lower and doesn't slow you down. If your suspension comes into play you add that mass and it increases the energy needed. By the time your whole bike has to move to clear anything you have lost a lot more energy. Bigger tires also help with rollover which again saves energy. :madman:

Anyway 30mm is the rims I would buy as they are the sweet spot.:thumbsup:

I used to trade KOM's with this guy when he Strava ed
My normal trail.


----------



## Dougal (Jan 23, 2004)

Steel Calf said:


> neither can the suspension, there's always some feedback.
> 
> A 2.6" tire has more volume than a 2.2" and thus will suck up more bumps, this advantage stays no matter how good your suspension is
> 
> ...


2.6" vs 2.2" is ~1cm taller. You cannot use all the compression a tyre can offer without damaging tyres and rims.

You are the only person stating the earth is flat.


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## Dougal (Jan 23, 2004)

alexbn921 said:


> I have been waiting for over 4 years for a decent 29x2.6, so I could bike a new bike around it. They haven't been around for 15 years.
> 
> I ran pneumatic tires. Getting the pressure even 1 psi off made a difference in grip. 3 psi off optimal and you might as well just go home because you wouldn't be competitive.
> I run 130mm to 110mm depending on the bike, so the 55mm of tire is half my suspension. That's not insignificant.
> ...


You've been waiting four years for a 29x2.6 when 29x2.5 has been out for years?





Tyres do have a different spring rate to a fork or shock. A much higher spring rate. Your fork (depending on rider weight) will have a rate about 30-60lb/in. Your tyre rate is a multiple of that.

If 1" stones (1" is not a rock) are not moving your fork then your fork needs work or your setup sucks.

If you think firmer tyres and suspension that moves robs more energy than hard suspension and soft tyres then you have failed my challenge above.

Show me anyone winning races on fat and soft tyres.

Anyone.

P.S. I think 27-30mm is ideal for me. Awaiting my new hubs to try my 30mm carbon rims.


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## Guest (Jun 5, 2017)

Dougal said:


> P.S. I think 27-30mm is ideal for me. Awaiting my new hubs to try my 30mm plastic rims.


fify


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## hece (Feb 27, 2017)

Something interesting to read for Dougal:
https://silca.cc/blogs/journal/part-4b-rolling-resistance-and-impedance

Brand new asphalt, 25mm GP4000 II road tyre and increasing pressure from 110 PSI will slow down the bike more i.e. total rolling forces increase? Isn't more pressure always better?


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## Osco (Apr 4, 2013)

My sweet spot for my trails was/Is

On 2.35 wides I liked 25-30mm ID rim widths.

On my current 2.8 wides my 35mm ID rims are IMHO perfect.
I'd run a 3.0" wide on these rims If I wanted a wider tire.
But not the 2.6 mainly because I like my low pressure rides
would not want to go back to more psi and narrower tires..

I'd want 30mm for 2.6 I think,,,,,,,


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## Guest (Jun 5, 2017)

Dougal said:


> If you think firmer tires and suspension that moves robs more energy than hard suspension and soft tires then you have failed my challenge above.
> 
> Show me anyone winning races on fat and soft tyres.
> 
> Anyone.


:yawn: one's tunnel vision will have this effect on their outlook. :ihih:


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## Suns_PSD (Dec 13, 2013)

There is a sweet spot for air pressures. It's not too low or high. Going just by feel I think my rear psi is pretty ideal at 27-29psi for instance. But I'd like to know for certain.

I am 100% certain that increased air pressure can reduce rolling resistance to a point just because I have for years added psi to my car tires, particularly for road trips, and I always see a substantial increase in mpg with this one change.

I have no doubt that over 30 psi is too high, but I'm also certain that under 20 psi is too low for my 2.5 tubeless 29er tires. POSITIVE.


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## RAKC Ind (Jan 27, 2017)

And the intensity grows.

Dougal,

You miss interpreted what I said.

The analogy of race cars is a fail. Again that's pavement vs offroad terrain. Nothing off-road uses skinny tires and high pressures (few exceptions but rare).

Wider tires isn't for everyone.

Nice full suspension is going to outperform a rigid when it gets rough almost regardless of tire width and pressures.

Comparing tire width to height as an absolute cannot be done. That only works with the same manufacturer and same tire product line.

30kph on a fat bike is no problem until it gets rough. However using that again is wrong. Fat bikes like so many others are purpose built. And a 5" tire is a big difference vs a 2.8-3.0 tire.

But to make a case in point, my racing is NOT done on 1.9 tires anymore really. You don't see anything below that till cycloscross.

History has already started to show us the benefits of wider.

There is a tipping point where the negatives overcome the gains.

That's why there is so much variation in mountain biking. Also why plus is becoming the rage. Because it's proving to outperform skinny tires in many ways. The ways all but the top racers care most about. And the negatives are minimal.

Plus didn't come to pass as a new thing for manufacturers to cram down our throats. It came because riders loved the positives of fat bikes but the negatives outweigh them for normal trail use.

I, like many here have the records to prove that plus is faster and more fun for us.

They've done the testing to show that there is benefits far outweighing the draw backs of plus tires. Only issue is that now they are looking for the "sweet spot". Much of which is due to if you look at most racers, my arms are the size of their legs.

If your total way of thinking was true then big knobbed road tires with premium suspension would be what all the racers used.

There is balancing points and trade offs for everything. The most efficient mountain bike would be a road bike in the sense that is your side of the debate.

Wrap your head around that for a second 

Sent from my SM-G950U using Tapatalk


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## Smithhammer (Jul 18, 2015)

Dougal said:


> Show me anyone winning races on fat and soft tyres.
> 
> Anyone.


Derrick Nobman won the Grand Enduro Series Finale last year (@ Grand Targhee, WY) on 3.0" tires. Not sure what his pressures were for this race, but I've ridden with him plenty, and he doesn't run particularly high pressures for his size/weight.

And now I'm sure you'll tell me it was some sort of anomaly, but you asked, and here's just one example for you....


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## Steel Calf (Feb 5, 2010)

I gonna receive my Specialized Fuse with 3.0" tires this week but after what I've learned in this thread I'll pump the tires up to 35psi and let the suspension do the job. Real men run hard tires!

What is a soft tire good for anyway, it's all a marketing fad


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## Dougal (Jan 23, 2004)

hece said:


> Something interesting to read for Dougal:
> https://silca.cc/blogs/journal/part-4b-rolling-resistance-and-impedance
> 
> Brand new asphalt, 25mm GP4000 II road tyre and increasing pressure from 110 PSI will slow down the bike more i.e. total rolling forces increase? Isn't more pressure always better?


Great find. Here's the most interesting graph from that page:









Better not go over 110psi then!



RAKC Ind said:


> And the intensity grows.
> 
> Dougal,
> 
> ...


Motorbikes use skinny tyres?



RAKC Ind said:


> History has already started to show us the benefits of wider.
> 
> There is a tipping point where the negatives overcome the gains.
> 
> ...


Yes there is a tipping point and plus is beyond that tipping point (for rolling resistance) unless you're on soft ground. In lieu of hard data this is bourne out by the XC race results. None of those guys use plus tyres because they're too slow.

Can plus be faster down certain tracks? 
Sure. If the traction benefits dwarf the rolling resistance losses and the speeds aren't high enough for instability to be a problem.



RAKC Ind said:


> I, like many here have the records to prove that plus is faster and more fun for us.
> 
> They've done the testing to show that there is benefits far outweighing the draw backs of plus tires. Only issue is that now they are looking for the "sweet spot". Much of which is due to if you look at most racers, my arms are the size of their legs.


For you and the places you ride. Sure a plus size can give the tradeoffs you want and need.

But that doesn't change the physics. It doesn't magically make them roll faster or suddenly gain control of their low frequency bounce. Those things mean for many applications they will never be the best choice.



RAKC Ind said:


> If your total way of thinking was true then big knobbed road tires with premium suspension would be what all the racers used.
> 
> There is balancing points and trade offs for everything. The most efficient mountain bike would be a road bike in the sense that is your side of the debate.


No. That does not represent any part of any of my arguments.

It's a fallacy known as the straw-man. You're trying to present the extreme end of a view point to ridicule it. While not understanding the view point enough to know what it actually is.

No-one (almost no-one) uses 1.9" tyres any more because they couldn't provide enough traction in varying conditions.
The plus tyres provide more traction but at the expense of rolling resistance and instability when run at low pressure and high speed.

The sizes in the middle are what suits not only the majority of riders but almost 100% of racers.



Smithhammer said:


> Derrick Nobman won the Grand Enduro Series Finale last year (@ Grand Targhee, WY) on 3.0" tires. Not sure what his pressures were for this race, but I've ridden with him plenty, and he doesn't run particularly high pressures for his size/weight.
> 
> And now I'm sure you'll tell me it was some sort of anomaly, but you asked, and here's just one example for you....


Great example, thanks.


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## jacksonlui (Aug 15, 2015)

That graph shows that lower pressures yielded lower Crr for the red line which is the machine roughened concrete which resembles aggressive trail riding better than the other ones which are more inline with smooth surfaces.

Sent from my SM-G930V using Tapatalk


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## Shredman69 (Apr 1, 2007)

We're all just beating a dead horse here. He's never going to get it. It is entertaining though.


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## alexbn921 (Mar 31, 2009)

Rough and/or Soft surfaces have steeper Impedance Lines making total rolling resistance higher and *Optimal Pressure Lower*

Better to set your pressure a few psi *below* the BreakPoint Pressure than to have it a few PSI above the BreakPoint Pressure


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## Dougal (Jan 23, 2004)

jacksonlui said:


> That graph shows that lower pressures yielded lower Crr for the red line which is the machine roughened concrete which resembles aggressive trail riding better than the other ones which are more inline with smooth surfaces.
> 
> Sent from my SM-G930V using Tapatalk


The graph stops at 60psi for a completely smooth tyre and machine cut concrete (8mm depth at 1 inch intervals). That's equivalent to a heavily gravelled track in a heavy frost (so the gravel is frozen in place).

This is the tyre:









I don't recommend them for mtb trails. Neither the surface, the tyre or the pressures are directly relevant to MTB. So you can't simply extrapolate.

But feel free to run your own experiments and post up the results.


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## jacksonlui (Aug 15, 2015)

The pt is thar Crr rises as a function of psi for the non smooth surface. Regardless of the minimum psi used in thos experiment, the trend indicates the same thing.

Sent from my SM-G930V using Tapatalk


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## alexbn921 (Mar 31, 2009)

LOL. Thread derailed. Nothing to see here. Carry on.


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## RAKC Ind (Jan 27, 2017)

Dougal 

You made my point, 1.9 tires don't provide the needed traction etc.

I've had my fat bike up to 25+ mph and that's where the bouncy tires get scary. But still lower rolling resistance than these insane knobbed tires.

I know it's a dead horse here and agreeing with me that plus tires fit some and not others, but it's a larger percentage than you realize and growing. 

Not sure why a picture of a continental road bike tire ended up in this thread but ok.

Sent from my SM-G950U using Tapatalk


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## Dougal (Jan 23, 2004)

jacksonlui said:


> The pt is thar Crr rises as a function of psi for the non smooth surface. Regardless of the minimum psi used in thos experiment, the trend indicates the same thing.
> 
> Sent from my SM-G930V using Tapatalk


CRR only rises above the break point. It doesn't continue to drop with reducing pressure as you think it does.



RAKC Ind said:


> Dougal
> 
> You made my point, 1.9 tires don't provide the needed traction etc.
> 
> I've had my fat bike up to 25+ mph and that's where the bouncy tires get scary. But still lower rolling resistance than these insane knobbed tires.


What fat tyres are you running and what are you comparing them to?



RAKC Ind said:


> I know it's a dead horse here and agreeing with me that plus tires fit some and not others, but it's a larger percentage than you realize and growing.


Yeah, E-bikes like steel_calf's Levo are ideal for them. They stop assisting at 25km/h so you can't get all out of shape.


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## jacksonlui (Aug 15, 2015)

Wow really? The data clearly indicates lower Crr at lower pressures for rough road versus lower Crr at higher pressure for smoother road.

Sent from my SM-G930V using Tapatalk


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## Dougal (Jan 23, 2004)

jacksonlui said:


> Wow really? The data clearly indicates lower Crr at lower pressures for rough road versus lower Crr at higher pressure for smoother road.
> 
> Sent from my SM-G930V using Tapatalk


This is the graph:









You seem to think the red line will continue to trend towards zero.
It won't.

It will hit a break point like the other two where rolling resistance rises with pressure drop.


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## Smithhammer (Jul 18, 2015)

Wow - most inanely painful thread on the Plus Forum ever?


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## alexbn921 (Mar 31, 2009)

Dougal said:


> You seem to think the red line will continue to trend towards zero.
> It won't.
> 
> It will hit a break point like the other two where rolling resistance rises with pressure drop.


Duh. You're the only one that is nitpicking this. We all understand what we are talking about and the exact PSI is going to be different in every case. Tire, bike, terrain, rider weight all make a difference.
What PSI should I run in my 29x2.6 on a tallboy with a total weight of 210lb. I have experimented and found the tipping point in traction, rolling resistance and confidence. That point is 16F/20R. +4psi is faster on the road but that's not what this is about. 
I also run my road bike tires at a significantly lower pressure than most roadies. It makes my bike faster and yes I have tested it.
2.6 is the goldilocks size for trail riders, enduro and DH. The casing will need to be different to work in the prefered rebound zone just like the smaller tires do now. 
XC Will probably top out around 2.35 as traction is much less important.


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## Dougal (Jan 23, 2004)

alexbn921 said:


> Duh


You know how the trends work, I know how the trends work. Jackonsui I'm not sure does



alexbn921 said:


> What PSI should I run in my 29x2.6 on a tallboy with a total weight of 210lb. I have experimented and found the tipping point in traction, rolling resistance and confidence. That point is 16F/20R. +4psi is faster on the road but that's not what this is about.


This is why this thread is going in circles. I'm talking about rolling resistance and you keep saying "no, because confidence, because traction etc".

Do you have issues with rim strikes at 16F?



alexbn921 said:


> 2.6 is the goldilocks size for trail riders, enduro and DH. The casing will need to be different to work in the prefered rebound zone just like the smaller tires do now.
> XC Will probably top out around 2.35 as traction is much less important.


Why is 2.6 the goldilocks size when we have had 2.5" forever?

Because marketing told us so?


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## Steel Calf (Feb 5, 2010)

This thread was meant to debate optimal rim width for 2.6" tires and grew with some great contributions until the same guy who already wrecked the "my next bike will have a___ drivetrain" thread joins in and we end up with rolling resistance on 25mm road tires!


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## Steel Calf (Feb 5, 2010)

Dougal said:


> Why is 2.6 the goldilocks size when we have had 2.5" forever?
> 
> Because marketing told us so?


blablabla you're still stuck on 26 inch wheels and judging by your question marks probably never rode 2.6 tires so go away.


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## jacksonlui (Aug 15, 2015)

Dougal said:


> This is the graph:
> 
> 
> 
> ...


No one said it will goto zero, only you did. You are oversimplifying things. You like to throw out general formulas which is only a small part of the big picture and are impractical. You think in a vacuum and refuse to believe what actually matters. Collecting data on rollers is good but unless you only ride on rollers, its not good data.

Lol. Youre a funny obstinate guy. I hope youre just trolling and not serious. I don't typically like to feed the trolls but I kinda think I did.

Sent from my SM-G930V using Tapatalk


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## Guest (Jun 6, 2017)

Shredman69 said:


> We're all just beating a dead horse here. He's never going to get it. It is entertaining though.





alexbn921 said:


> LOL. Thread derailed. Nothing to see here. Carry on.





Smithhammer said:


> Wow - most inanely painful thread on the Plus Forum ever?


Dougal is the gift that keeps on givin.


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## Guest (Jun 6, 2017)

Steel Calf said:


> This thread was meant to debate optimal rim width for 2.6" tires and grew with some great contributions until the same guy who already wrecked the "my next bike will have a___ drivetrain" thread joins in and we end up with rolling resistance on 25mm road tires!


true enough.


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## Tjaard (Aug 17, 2007)

moved


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## Tjaard (Aug 17, 2007)

Back on topic:



bdundee said:


> I ran 2.8 NN and RR's on 30I rims without issue for a summer, thought they were great. I would think to save sidewall exposure 30I rims for 2.6's would be optimal. That being said it goes against what Maxxis is saying.


On most brands, a 2.6" tire would get lot's of sidewall exposed on a rim wider than i30mm. The Maxxis Wide trail should be different as they are designed for that wider rim.

We are basically looking at two different things in choosing rim width:


Lateral Support
Tread Coverage


For lateral support, wider is mostly better. This becomes a bigger issue with fatter tires. Not only do you need a wider rim simply to keep the ratio of tire width to rim width the same, but a wider tire is also taller, increasing the flex in the casing even at the same ratio of rim/tire width.

An approximation to look at this is to square the tire width and then divide by rim width. In this case to get the same support as a *2.3"on a i27mm* rim, for a wider tire you would need:

*2.6" ~i32mm
2.8" ~37mm
3.0" ~42mm*

Lateral support matters more for people who corner hard on firm surfaces and on tires with good grip. Stiff sidewalls can help increase support. People who ride in slippery conditions on soft ground are less likely to reach the limits of lateral support of their tire/rim system.

The other issue is tread coverage and cross section shape:
This is only determined by tire width, so to keep the same shape as a *2.3"on a i27mm* rim, for a wider tire you would need:

*2.6" on i29mm
2.8" on i32mm
3.0" on i34mm**

So there you have the conundrum for people who need lot's of lateral support:
The rim that is _*wide enough to support your big tire in the corner*_ will leave the tire shape much wider and flatter than a standard tire, _*exposing the sidewall to cuts, creating an excessively flat tread shape*_, and losing traction at extreme angles.

Supposedly the Maxxis wide Trail tires are supposed to address this, increasing the tread width and shape to the new shape of the casing on a wide rim.

*This matches up well with Stans suggestions, so it seems their recommendations are based on tire shape, but do not address lateral support.


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## nitrousjunky (May 12, 2006)

Tjaard said:


> Back on topic:


THANK YOU!! I have decided to go with a i30/2.6 on the rear of my bike and i35/2.6-2.8 on the front.



Smithhammer said:


> Wow - most inanely painful thread on the Plus Forum ever?


+ 1 million!


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## Osco (Apr 4, 2013)

Smithhammer said:


> Wow - most inanely painful thread on the Plus Forum ever?


Yeah some here wanted to be helpful and some as always want to show how much they know to Impress people they will never meet so they can get that confirmation that sez,, ' I AM THE GREATEST',, The look at me peeps


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## Osco (Apr 4, 2013)

RAKC Ind said:


> And the intensity grows.
> 
> Dougal,
> 
> ...


Then people like this come along and post, Gives me hope that there are still smart people out there who get It and are not hung up on meaningless detour's of the mind In this never ending reach for a better ride that we all seek ~


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## Osco (Apr 4, 2013)

Smithhammer said:


> Derrick Nobman won the Grand Enduro Series Finale last year (@ Grand Targhee, WY) on 3.0" tires. Not sure what his pressures were for this race, but I've ridden with him plenty, and he doesn't run particularly high pressures for his size/weight.
> 
> And now I'm sure you'll tell me it was some sort of anomaly, but you asked, and here's just one example for you....


Brilliant ! Fantastic !


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## Steel Calf (Feb 5, 2010)

nitrousjunky said:


> THANK YOU!! I have decided to go with a i30/2.6 on the rear of my bike and i35/2.6-2.8 on the front.


same here. i30 enduro rim rear, i35 all mountain rim front both with Nobby Nic 2.6 tires. The sidewalls are slightly more exposed on the 35mm rim but I like to run as low pressures as possible on the front wheel thus may be able to leverage the additional rim width


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## nitrousjunky (May 12, 2006)

Steel Calf said:


> same here. i30 enduro rim rear, i35 all mountain rim front both with Nobby Nic 2.6 tires. The sidewalls are slightly more exposed on the 35mm rim but I like to run as low pressures as possible on the front wheel thus may be able to leverage the additional rim width


I may be the same for a bit. Have a NN 2.6 to test on the back and have a 2.5 DHF on hand to run too if needed. May run NN on both ends until the Rekon & McFly are available.


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## Tjaard (Aug 17, 2007)

Steel Calf said:


> same here. i30 enduro rim rear, i35 all mountain rim front. The sidewalls are slightly more exposed on the 35mm rim but I like to run as low pressures as possible on the front wheel thus may be able to leverage the additional rim width


That seems like a good set-up.
On the front you can avoid sidewall damage a bit easier, but at the same time any squirming will feel really upsetting.

Ideally you would run a stiffer casing in the back to help prevent squirming form the narrower rim and to prevent pinch flats, which are more likely in back.

In front you could run a slightly lighter casing since the wider rim will keep it stable and pinch flats are much rarer and you can avoid scuffs and cuts a bit easier.


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## Smithhammer (Jul 18, 2015)

Dougal said:


> Great example, thanks.


I'm glad we agree.


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## Dougal (Jan 23, 2004)

Steel Calf said:


> This thread was meant to debate optimal rim width for 2.6" tires and grew with some great contributions until the same guy who already wrecked the "my next bike will have a___ drivetrain" thread joins in and we end up with rolling resistance on 25mm road tires!


The rim width question was answered early on. You risk sidewall and rim damage by going too wide. But if they aren't an issue for you then go for it.

When you go too far:









9T cassette and Mulefut would look good on that Fattie.


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## akindo (Apr 16, 2009)

Word.


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## akindo (Apr 16, 2009)

Amazing.


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## akindo (Apr 16, 2009)

Amazing!


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## akindo (Apr 16, 2009)

Word, intense as.

I'm gonna do 2.6 tires on 30mm rims on a steel hardtail, rigid fork!


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## akindo (Apr 16, 2009)

Tjaard said:


> Back on topic:
> On most brands, a 2.6" tire would get lot's of sidewall exposed on a rim wider than i30mm. The Maxxis Wide trail should be different as they are designed for that wider rim.
> 
> We are basically looking at two different things in choosing rim width:
> ...


Such a good post, it all makes sense now, after reading through the thread, and then this strong finaliser!


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## Steel Calf (Feb 5, 2010)

Dougal said:


> The rim width question was answered early on. You risk sidewall and rim damage by going too wide.


I started this thread and after riding 2.6" tires on both 30 and 35mm rims I call the often brought up "sidewall are more exposed on the wide rim" argument bullshit.

In fact, once rider weight is applied on the tire the lower area of the sidewalls are more exposed on the narrower 30mm rim.

However, two other arguments are for 30mm rims in the rear are still valid: Added stability and lower rolling resistance due to rounder tire shape.


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## Dougal (Jan 23, 2004)

Steel Calf said:


> I started this thread and after riding 2.6" tires on both 30 and 35mm rims I call the often brought up "sidewall are more exposed on the wide rim" argument bullshit.
> 
> In fact, once rider weight is applied on the tire the lower area of the sidewalls are more exposed on the narrower 30mm rim.
> 
> However, two other arguments are for 30mm rims in the rear are still valid: Added stability and lower rolling resistance due to rounder tire shape.


Nope. You may want to try some different tyres on different rims as sidewall exposure does not work the way you think it does.

With 2.35" 30mm is as wide as I can go with the sidewalls level with the knobs. Narrower rims and the knobs protrude furthur then the sidewalls. Wider rims and the sidewalls protrude further than the knobs.
It's a very simple and logical relationship.

Here's a nice example. 2.3" tyres on 40mm rims and the sidewalls have been eaten:

__
http://instagr.am/p/BZc8a1QAuas/

For me 25-27mm is the target for 2.3-2.4". 30mm would be about right for 2.6" on my trails. 35mm will expose the sidewalls too much. If sidewall exposure is not an issue then feel free to go wider in rim.


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## sriracha (Jun 23, 2004)

Interesting thread, ignoring all the drama. lol

So, I really can't decide on my next wheel set. I'm planning to build a 27.5 set of wheels for my Canfield Balance. The Balance can barely fit a 2.8" on an i35 rim.

I plan to run the Maxxis DHRII 2.4WT, DRF 2.5WT and eventually the Maxxis DHRII 2.6.

I keep going back and forth between the Spank Oozy Trail rims... i30 or i35. 

Planning to run DHRII 2.4WT up to DHRII 2.6... i30 or i35????

Help me decide!


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## Shredman69 (Apr 1, 2007)

i35.


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## Dougal (Jan 23, 2004)

Is sidewall damage an issue where you ride?

Sent with 100% recycled electrons.


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## Guest (Oct 29, 2017)

stop feeding the troll you's guys....


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## Shredman69 (Apr 1, 2007)

nvphatty said:


> stop feeding the troll you's guys....


Oh ****! I forgot he was here!


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## noose (Feb 11, 2004)

alexbn921 said:


> Duh. You're the only one that is nitpicking this. We all understand what we are talking about and the exact PSI is going to be different in every case. Tire, bike, terrain, rider weight all make a difference.
> What PSI should I run in my 29x2.6 on a tallboy with a total weight of 210lb. I have experimented and found the tipping point in traction, rolling resistance and confidence. That point is 16F/20R. +4psi is faster on the road but that's not what this is about.
> I also run my road bike tires at a significantly lower pressure than most roadies. It makes my bike faster and yes I have tested it.
> 2.6 is the goldilocks size for trail riders, enduro and DH. The casing will need to be different to work in the prefered rebound zone just like the smaller tires do now.
> XC Will probably top out around 2.35 as traction is much less important.


I want to run 2.6 at those low pressures but have 25mm internal alloy rims. What are your rims? I might rebuild my wheels with 30-32mm internal rims.


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## Dougal (Jan 23, 2004)

noose said:


> I want to run 2.6 at those low pressures but have 25mm internal alloy rims. What are your rims? I might rebuild my wheels with 30-32mm internal rims.


2.6" DHF measures 63mm across the knobs and 60mm casing on a 27mm internal rim at 30psi.


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## noose (Feb 11, 2004)

Dougal said:


> 2.6" DHF measures 63mm across the knobs and 60mm casing on a 27mm internal rim at 30psi.


Who's question were you answering or was that just a random thought?

Sent from my XT1635-01 using Tapatalk


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## Dougal (Jan 23, 2004)

noose said:


> Who's question were you answering or was that just a random thought?
> 
> Sent from my XT1635-01 using Tapatalk


Take a look a the thread title at the top of your screen.


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## noose (Feb 11, 2004)

Dougal said:


> Take a look a the thread title at the top of your screen.


I was asking a poster a specific question not baiting a troll.


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## Dougal (Jan 23, 2004)

noose said:


> I was asking a poster a specific question not baiting a troll.


Oh this is funny. Providing relevant information makes you troll. But asking vague leading questions doesn't.

Hmmm.


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## Guest (Feb 2, 2018)

..:skep:


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## Klurejr (Oct 13, 2006)

Stay on topic, be civil, no rude language.


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## Kennythevamp (Aug 1, 2018)

akindo said:


> Word, intense as.
> 
> I'm gonna do 2.6 tires on 30mm rims on a steel hardtail, rigid fork!


Considering buying some 2.6 and doing this on my hardtail right now. How did it work out for you?


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## Kennythevamp (Aug 1, 2018)

Steel Calf said:


> I gonna receive my Specialized Fuse with 3.0" tires this week but after what I've learned in this thread I'll pump the tires up to 35psi and let the suspension do the job. Real men run hard tires!
> 
> What is a soft tire good for anyway, it's all a marketing fad


Have you kept with the 3.0 tire? I'm considering going smaller.


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## Transwave (Oct 7, 2007)

I am running 2.6 and 2.8 tires on 32mm ID rims. For 2.6 tires this rim width seems to be the sweet spot. For 2.8 i would prefer 35mm ID. If i had 3.0 tires i would not settle for anything narrower than 38mm ID.


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## eb1888 (Jan 27, 2012)

Not every 2.6 or 2.8 tire is the same volume with the same sidewall flexibility or with the same rounded tread profile. And that's great because there's different terrains with trails that get you riding at different speeds. On my trails 40mm inner goes with the high volume very rounded profile flexible sidewall 2.6 tire that fits the terrain. If I had longer down runs and higher speeds I'd look at a thicker sidewall tire and put it on a 35mm rim.


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## Shredman69 (Apr 1, 2007)

26 x 2.8 120tpi DHRII EXO on 40i LB, tubeless with no sealant. It’s the ****. Light, fast and monster trucks over or up anything! I love it!


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## Trojan366 (Oct 4, 2016)

I haven’t read every post in this thread so hopefully my opinion isn’t repeating someone else. I run 2.4dhr and 2.5dhf on 29mm internal stans flows. I run 2.8dhf and dhr on the 35mm Stan’s baron. I am a fan of how they fit and the tire profile. I’d bet either rim would be ok with a 2.6 but Based on Stan’s low profile I would think the 32mm sentry would be an excellent option.


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## Steel Calf (Feb 5, 2010)

Kennythevamp said:


> Have you kept with the 3.0 tire? I'm considering going smaller.


No I've now downsized to Nobby Nic/Rocket 2.8" on 40mm rims. 3.0" tires didn't work for me due to the too large undamped air volume, I don't see any grip advantage either, the Specialized tires were heavier than a 2.6" Magic Mary


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## JACKL (Sep 18, 2011)

Shredman69 said:


> 26 x 2.8 120tpi DHRII EXO on 40i LB, tubeless with no sealant. It's the ****. Light, fast and monster trucks over or up anything! I love it!


Sweet! I don't know how you stuffed them in there. Without a doubt you gained quite a bit of rollover, and glad to hear the bike still likes to party!


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## Shredman69 (Apr 1, 2007)

JACKL said:


> Sweet! I don't know how you stuffed them in there. Without a doubt you gained quite a bit of rollover, and glad to hear the bike still likes to party!


Hell yeah! I actually have plenty of clearance too! :thumbsup:


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## Miker J (Nov 4, 2003)

Shortly after my reply to this thread last June, I ended up trying the 2.6"x 275 flavor. They are in fact amazing trail tires. Since then I've had the opportunity to run them on both i29 and i35 rims.

They feel better on the i35 rims. Not worlds better, but I found it quite noticeable.


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## PuddleDuck (Feb 14, 2004)

Miker J said:


> Shortly after my reply to this thread last June, I ended up trying the 2.6"x 275 flavor. They are in fact amazing trail tires. Since then I've had the opportunity to run them on both i29 and i35 rims.
> 
> They feel better on the i35 rims. Not worlds better, but I found it quite noticeable.


Thanks Miker J, which tyres did you try?


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## Steel Calf (Feb 5, 2010)

Miker J said:


> They feel better on the i35 rims. Not worlds better, but I found it quite noticeable.


front or rear wheel? how many psi?

I'm inclined to agree with your assessment since I mixed 30mm rear and 35mm front with 2.6 tires myself and the 35mm rim just looks more proportional from an optical standpoint.

Schwalbe themselves recommends 30-40mm rims for their 2.6" tires, which puts the currently popular 30mm + 2.6" spec right on the edge of being too narrow, however I also think that one can only feel a difference between these widths below a certain air pressure.


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## Miker J (Nov 4, 2003)

Maxxis. 2.6 x 275

Front, DHF 3c. About 17 psi.

Rear, Forekaster and Rekon, both dual compound. About 20 psi

Tubeless of course.

I weight about 175-180 with gear.


I've a second wheelset with i29 rim and now run Maxxis 2.5" WTs one them. DHF/DHR2. They are less cushy, slower rolling, but bring a much more controlled ride in faster, harsher conditions. They corner better at speed. I think of the 2.6 tires as perfect trail tires, and the 2.5 tires as better AM/enduro-style tires.


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## Steel Calf (Feb 5, 2010)

Miker J said:


> Maxxis 2.5" WTs one them. DHF/DHR2. They are less cushy, slower rolling, but bring a much more controlled ride in faster, harsher conditions.


same experience here. The 2.6" were lighter too


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## PuddleDuck (Feb 14, 2004)

Great, thanks!



Miker J said:


> Maxxis. 2.6 x 275
> 
> Front, DHF 3c. About 17 psi.
> 
> ...


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## Dougal (Jan 23, 2004)

I ran a 27x2.6" DHF Max Terra on a 30mm internal rim all last summer. 25psi. Tubed.

No problems at all with stability. I need to run higher pressure to prevent rim strikes. Still managed to kill the rim at 25psi though.


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## yamaha46 (Jul 17, 2009)

How much do you weigh?
I think rider weight varies how low you can run your pressures.
Also how hard you push your bike through rocky terrain.


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## jacksonlui (Aug 15, 2015)

I run 19psi on my 27.5x2.6 dhf front tire mounted to a 36mm ID. Im 185lbs and works for me. PSI seems to vary per person but its a good starting pt.

Sent from my SM-G930V using Tapatalk


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## Dougal (Jan 23, 2004)

yamaha46 said:


> How much do you weigh?
> I think rider weight varies how low you can run your pressures.
> Also how hard you push your bike through rocky terrain.


70-75kg.


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## yamaha46 (Jul 17, 2009)

Interesting that you rim striked at that pressure.
I'm 70kg running 2.8 reckons on i45 rims at 16/14psi. 
I like to go as soft as I can. I ride some fairly rocky sections. 
Either you ride into rock edges allot harder than I do, or the wider rims and .2 bigger tyres allow for allot lower pressures?
I should probably ride at 1 or 2 psi more for safety.


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## Dougal (Jan 23, 2004)

yamaha46 said:


> Interesting that you rim striked at that pressure.
> I'm 70kg running 2.8 reckons on i45 rims at 16/14psi.
> I like to go as soft as I can. I ride some fairly rocky sections.
> Either you ride into rock edges allot harder than I do, or the wider rims and .2 bigger tyres allow for allot lower pressures?
> I should probably ride at 1 or 2 psi more for safety.


We have sharp fractured rocks which provide some real challenges in the tyre and rim department. One group ride last season we did three back wheels. Mine I was able to true back into good enough shape, the other two with irreparable dents that would never seal again. But could get you home with a tube inside.

I was running 35psi rear, the other guys running 15-20.

Given the option of running heavier tyres and cush-cores or simply upping the pressure. I simply up the pressure and use better suspension to keep the comfort and grip.


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## yamaha46 (Jul 17, 2009)

Yes that explains it. I guess the rocky sections I ride are more rounded rocks.
There is one section I try to avoid that has sticking out jagged rocks.
I run low pressures to get some comfort from my hardtail.


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## Miker J (Nov 4, 2003)

Dougal said:


> We have sharp fractured rocks which provide some real challenges in the tyre and rim department. One group ride last season we did three back wheels. Mine I was able to true back into good enough shape, the other two with irreparable dents that would never seal again. But could get you home with a tube inside.
> 
> I was running 35psi rear, the other guys running 15-20.
> 
> Given the option of running heavier tyres and cush-cores or simply upping the pressure. I simply up the pressure and use better suspension to keep the comfort and grip.


Not challenging anything here, as I'm sure you know what works best for you, but at higher psi those 2.6" tires loose their cush and I find them too bouncy (uncontrolled rebound from the tire itself?). At that point, I move over to the 2.5" WT Maxxis flavor which is a more aggressive tire made for harding riding.

Like I mentioned above, the 2.6" tires are great for trail riding. For more aggressive, higher speed riding (AM/Enduro-style) I use my 2nd wheelset with the 2.5" WT flavor.


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## Dougal (Jan 23, 2004)

Miker J said:


> Not challenging anything here, as I'm sure you know what works best for you, but at higher psi those 2.6" tires loose their cush and I find them too bouncy (uncontrolled rebound from the tire itself?). At that point, I move over to the 2.5" WT Maxxis flavor which is a more aggressive tire made for harding riding.
> 
> Like I mentioned above, the 2.6" tires are great for trail riding. For more aggressive, higher speed riding (AM/Enduro-style) I use my 2nd wheelset with the 2.5" WT flavor.


What happens is that tyres have a natural frequency which feels unstable (uncontrolled bouncing) when it gets close to the natural frequency that you and the bike bounce up and down at.

To get away from this unstable zone you can either go firmer or softer. The bigger your tyres volume the lower the frequency and the more pressure you need to get them out of that unstable zone.

This is why fat bikes and plus bikes have issues at speed. The big volumes and low pressures put the tyre bounce frequency into that unstable zone.

It was the taller carcass of the 2.6 that let me run lower pressures while avoiding most rim strikes. 2.35 minion and 2.4 high roller I was running at 35psi and still getting strikes. I'm using it to keep my front rim 2.6" away from the rocks. It's still got great grip and stability with that at 25psi. I have 170mm of suspension for the rest.


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## LezRide (Sep 6, 2019)

32mm sounds pretty optimal for 2.6 but options either seem to be going away or is carbon. Sad panda.


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