# 32t or 34t chainring thoughts?



## azmtbr (Jul 15, 2006)

I've been riding single speed for a number of years now 32x16 or 32x17 which for me has worked and aloud me to ride most everything here in Phoenix and other parts of Arizona. I had a couple of stainless steel chain rings in the last few months bend/warp. My LBS that I've been dealing with for years suggested a 34t. I tried it and actually liked it but was also riding with a 16 (I'm a masher). Well it bent and was a stainless steel ring to. Now my shop is saying to go back to the 32 and ride aluminum rings. I was thinking steel or ti. So my question(s) is 1. 32 or 34 any major differences or is it more personal? 2. What ring material would you suggest for strength and durability? Rings did not bend from rock hits.
Never had this problem in the past just in the last 4 months. Sorry for the long post and thanks for your thoughts. Oh and I ride a 29er SS. if that info helps.


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## Mr Pink57 (Jul 30, 2009)

I hear a lot of the issues are coming more from a 104BCD since it is 4 bolts it causes it to bend (read Surly Stainless Steel chainrings). A way to fix this is to go to a 5 bolt pattern from what I understand.

Right now I am a ***** compared to you, I just went from 32x20 to 33x20 and probably go to 34x20 next year.

If I was going Ti I would definitely look at what ISAR can offer you at Homebrewed.


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## azmtbr (Jul 15, 2006)

Interesting, I'm running 104bcd slx and the rings are surly's that I've had problems with. The Homebrewed looks nice I've been on there site a few times now. Thanks for your thoughts.


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## aka AK (Jan 18, 2004)

*Why not a 33*

Q #1. I have ran a 33X17 for 8 years now and really like this combo. It really is personal preference though and the gear ratio is slightly different that anything out there. Only other combo to get that ratio would be 35X18.


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## umarth (Dec 5, 2007)

God. Wait until Sparty catches wind of this....

(I do 5 bolt 34t from Homebrewed.)


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## cr45h (Jan 13, 2007)

i've had issues with the steel surlys, i bent a 5 bolt. i'd go aluminum and 5 bolt if possible


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## CB2 (May 7, 2006)

cr45h said:


> i've had issues with the steel surlys, i bent a 5 bolt. i'd go aluminum and 5 bolt if possible


Me too.
I don't know about Dan's stainless rings, but I've bent both 4 and 5 bolt Surly's. 
His aluminum rings are reversible so you get double life out of them.


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## Just1Gear (Jan 14, 2011)

I've heard multiple stories of the Surly rings failing, design issue? I've been running Salsa 4 bolt (32x15/16) for a few years on my 26 without issue. Now I run 34x18 but with a "Real" 5 bolt on my 29r, all aluminum....


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## Sparticus (Dec 28, 1999)

I'm not fond of...

[] the way aluminum rings & cogs wear out relatively quickly. Maybe it's the gritty slurry I ride through here in the Pacific North Wet for 8 months of the year. Whatever... not fond of aluminum's wear characteristics.

[] 4-bolt cranks. Somebody in the bike industry decided to bait a new line with 4-bolt cranks and sure enough the public swallowed it. Fewer spider ears... dumb, IMO.

[] how easily Surly chainrings bend (particularly on 4-bolt cranks, but evidently they'll bend on just about anything). Anyway for whatever reason, even though they bend easier than aluminum rings, they seem to last longer. Go figure.

So my solution was to buy a couple ti rings from Dan at Homebrewed Components. Well, I guess I shouldn't call it a solution yet because I haven't even ridden them yet. One is still on order and the other is mounted on a bike that's so new I haven't even ridden it. Anyway my theory is ti will wear like steel but not be so prone to bending.

Time will tell.

--sParty


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## Grendel (Sep 2, 2004)

I have been running a Blackspire 34t DH ring on my singlepeed for years now, its been great, no issues. I lived in AZ for years, rode DD almost everyday... since moved to New England, but still using the same ring, just a different cog in the back. Personally I really like the move from a 32t to a 34t... felt "better, more comfortable" for me.


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## meltingfeather (May 3, 2007)

OP- 33?



Sparticus said:


> Anyway my theory is ti will wear like steel but not be so prone to bending.


IMO it would take some carefully considered design for this theory to play out.
The wear? Absolutely.
Titanium is about twice as flexible as steel with about the same yield point and 60% of the unit weight.
So if you built a titanium ring of the same weight as steel you'd have a ring that is still more flexible but with 1.75X the yield strength (simplifying here). Do people build ti rings that weigh the same as steel? There are trade-offs somewhere, but the main advantage of Ti is it's steel-like performance with _less weight_.


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## Sparticus (Dec 28, 1999)

meltingfeather said:


> OP- 33?
> 
> IMO it would take some carefully considered design for this theory to play out.
> The wear? Absolutely.
> ...


Thanks for bringing your slide rule to the party, MF.

--sParty

P.S. Personally I prefer your beanie-copter avatar, though I'm sure you have a scientifically defendable reason for using your current one.


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## meltingfeather (May 3, 2007)

Sparticus said:


> Thanks for bringing your slide rule to the party, MF.
> 
> --sParty


slide rules are more a your-generation thing (i never learned how to use one), but i appreciate history to an extent, even if it's mostly boring to me. rather than discuss your theory, i guess personal jabs are more your style? when logic fails...
if this is a party to you maybe you should come down to atx for a weekend or something. we'll have some real fun. 


Sparticus said:


> P.S. Personally I prefer your beanie-copter avatar, though I'm sure you have a scientifically defendable reason for using your current one.


nope. i took snapped the picture with my iphone after a ride and i like it.
:thumbsup:


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## Sparticus (Dec 28, 1999)

meltingfeather said:


> slide rules are more a your-generation thing (i never learned how to use one), but i appreciate history to an extent, even if it's mostly boring to me. rather than discuss your theory, i guess personal jabs are more your style? when logic fails...
> if this is a party to you maybe you should come down to atx for a weekend or something. we'll have some real fun.
> 
> nope. i took snapped the picture with my iphone after a ride and i like it.
> :thumbsup:


Not a jab. Shucks, I said thanks.

Actually I think you're much better at jabbing than I am. Tough part is you're usually right. Different styles, that's all.

I don't know how to use a slide rule, either. I do okay with a bicycle, tho.

You're welcome up thisaway, too. Ever been to Orygun to ride?

--sParty

P.S. It is a nice photo. What is it?

P.P.S. Hey, we're not so different, MF. We both use iPhone. There's some common ground, anyway...


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## Cygnus (Jan 7, 2004)

I like 34 because it gives me a broader range of gear ratios than 32 to suit my riding. I find that as i get stronger, i gear up, not down.

i must be easy on chainrings as i have only broken one. have had great luck with blackspire too.

why do many inter tidal animals (e.g., starfish) have 5 legs and not 4? same reason a 5-spoked crank and chainring is stronger than 4.


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## henrymiller1 (Apr 25, 2008)

34!


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## meltingfeather (May 3, 2007)

Sparticus said:


> Not a jab. Shucks, I said thanks.


misinterpreted. my apologies. i'm conditioned by the digs i normally get.  


Sparticus said:


> You're welcome up thisaway, too. Ever been to Orygun to ride?


Nope. I'd love to though. Used to date a girl from p-town and i've done some rock climbing (bend) and boarding (hood) there though. a buddy of mine went to Reed and i spent a little time up there then... frickin' nutz those kids. ut:


Sparticus said:


> P.S. It is a nice photo. What is it?


thanks. it's the satellite link-up on a news van. not too long ago they found a dead guy floating in a creek at a park where i ride a lot. when i got back from my first lap there were news crews all around and i snapped the shot before i figured out wtf was going on. i'm kind of a photo junkie.


Sparticus said:


> P.P.S. Hey, we're not so different, MF. We both use iPhone. There's some common ground, anyway...


i'm sure we'd get along just fine. i'm actually a pretty laid back dood... with a knack for details and analysis.  i was the sore thumb in engineering school that was also an artist and threw crazy parties... never did quite fit in with the engineering crowd, even though i do pretty well at it.


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## Sparticus (Dec 28, 1999)

meltingfeather said:


> ...
> 
> thanks. it's the satellite link-up on a news van. ...


Cool. Until I took a hard look at it, I assumed it was a dandelion awaiting a brisk breeze. Now it's obvious.

ATX... after googling I expect you're either in Austin, TX or Atbasar Airport, Kazakhstan.

I'm not visiting you to go riding if you're in Kazakhstan. Austin, that's more reasonable. Good singlespeeding there?

--sParty

P.S. I lied. I was jabbing you. Thanks for going along. Seriously. The internet is such a hard place to figure what people really mean. I meant no harm, just kidding. But that can be dangerous ground here. I expect we're both reasonable people. I'm just not as smart as you.


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## noosa2 (May 20, 2004)

azmtbr said:


> So my question(s) is 1. 32 or 34 any major differences or is it more personal? 2. What ring material would you suggest for strength and durability?
> Never had this problem in the past just in the last 4 months. Sorry for the long post and thanks for your thoughts. Oh and I ride a 29er SS. if that info helps.


 I have had good luck with Rennen 7075-T6 aluminum chainrings.


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## bikeny (Feb 26, 2004)

meltingfeather said:


> OP- 33?
> 
> IMO it would take some carefully considered design for this theory to play out.
> The wear? Absolutely.
> ...


This is not really true. It all depends on what alloy of each material is being used. The Surly rings are made of a very soft stainless, which is much weaker than your standard carbon steel. This is why the Surly rings bend so easily. Unfortunately, Homebrewed (Dan) does not make stainless rings, only stainless cogs. But his cogs are made from heat treated 17-4 stainless, which if very hard and strong, but expensive. I believe that's why he doesn't make chainrings out of this material, the cost would be so high, you would be better off with titanium. Titanium rings can also be made from different alloys. The good ones (like Boone and Homebrewed) are made of 6-4 which is harder/stronger that 3-2.5. Someone else may chime in with the exact details, but that is the jist of it.

I would definately steer clear of the Surly stainless rings, especially the 4 bolt variety. Get either a good aluminun singlespeed chainring, or invest in a nice titanium chainring from Homebrewed Components, they are well worth the cost.

I am also one of those retro grouches that hates 4 bolts cranks. All of my geared bikes still use 5 bolt cranks. But for by singlespeed, I like the spiderless setup even more. I have been very hapilly riding a set of M950 XTR cranks with a Boone spiderless ring for many years. Yes, I have been riding the same ring and cog for years, with barely any noticeable wear. I have been wanting to step up to some external bearing cranks, and finally took the plunge. It had to be a spiderless setup, of course, so there are a few options now. I think the cheapest is the SRAM X7 2x10 S1400 crank which has a removeable spider and a Homebrewed aluminum spiderless ring. I splurged for the titanium ring because, well I have a problem! Other options are the pricier SRAM 2x10 cranks and the new Middleburn X-type.I have not received either of these yet, so I cannot comment on performance yet.

Oh yeah, I like running a 34t ring as well. It's a little smoother and last a bit longer.

Sorry for the long winded reply, just wanted to throw all that out there!

Mark


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## 1SPD (Apr 25, 2010)

I've been running a 32t on my XTR M960 4 leg for over a year now. I have yet to have any problems with either of them but I can see how/why a 4 star would not be as strong. Perhaps when it finally breaks I will go spiderless w/ some sort of carbon crank at that point. 

I have been on a 32:18 since going ss last year and have done fine. Started riding 32:16 over the winter but then built up a 29er and went back to the 18. I have a brand new 33t HB ring and am thinking of slapping that on to give it a shot. I'm sure I will feel the difference and take a bit of a butt woopin initially but hopefully I can grow into it if you will.


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## 1SPD (Apr 25, 2010)

Because I sucked at math and damn near bombed out of physics, I see the chart and can make sense of it but have questions.

The feel we all get pedaling is also different based on the size of wheels you are running. I mean, a 32:16 was challenging for me on the 26er. But when I went to the 29er, the 32:18 felt almost the same as the 16 on the 26er. I suspect that bumping up to a 33:18 will once again give me that feeling of shifting to a harder gear. 

With all of that said, how would you compair this ratio on a larger wheeled bike? Does that make any sense?


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## Saddle Up (Jan 30, 2008)

I don't want to derail the thread, but which 5 bolt cranks are you guys referring to, what BCD? I have a couple of Deore FC-MT60 cranks that cleaned up quite nicely. They are 110mm BCD. The intention was to use them with triple chainrings on geared bikes but....

Problem is, the smallest ring available is 34t, 33t with modification to the crank, maybe it's not a problem after all?


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## Sparticus (Dec 28, 1999)

1SPD said:


> ...
> 
> With all of that said, how would you compair this ratio on a larger wheeled bike? Does that make any sense?


Compute gear inches:
#ring teeth / #cog teeth x wheel diameter in inches = gear inches.

For example, a 34x20 drivetrain on a 26" wheel bike is approximately the same gear inches as a 32x21 drivetrain on a 29" wheeled bike.
(34 / 20) x 26 = 44.20 gear inches
(32 / 21) x 29 = 44.19 gear inches

Indistinguishable pedaling difference.

--sParty


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## 1SPD (Apr 25, 2010)

Ok so,
(32/18)29= 51.62
(33/18)29= 53.07

Doesn't look like much but I bet it is something that my little legs will not like!

With the above calculations I would say that the change in wheels size while keeping the same drive train ratio was quite a jump. I went from 46.28 to 51.62. That being said, the jump to a 33t on the 29er probably is not that bad at all and very well may be something I try to do towards the end of this month depending on much riding I can get in. I am also thinking about making the change to try to take some of the slack out of my chain ant to allow me to push my sliders forward a little bit, thus shortening the wheelbase of the bike ever so slightly. Might be time to play with this tonight since it is raining out here for the next 3 days.


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## 1SPD (Apr 25, 2010)

Oh, thanks Sparty. Looks like you smarter than me! Damn!


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## bikeny (Feb 26, 2004)

Saddle Up said:


> I don't want to derail the thread, but which 5 bolt cranks are you guys referring to, what BCD? I have a couple of Deore FC-MT60 cranks that cleaned up quite nicely. They are 110mm BCD. The intention was to use them with triple chainrings on geared bikes but....
> 
> Problem is, the smallest ring available is 34t, 33t with modification to the crank, maybe it's not a problem after all?


The most commonly used 5 arm BCD used to be 94mm, or 'compact'. You can get chainrings down to 29t for those. With 110 BCD cranks, 34 or 36 is pretty much it. You can of course compensate with a larger cog if you go this route, and the rings/cogs will last longer and run smoother as well. Those are certainly useable cranks if you keep the above in mind. 94mm BCD cranks can be found pretty easily on Ebay from Shimano, Race Face, Sugino and others.


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## Sparticus (Dec 28, 1999)

1SPD said:


> ...
> With the above calculations I would say that the change in wheels size while keeping the same drive train ratio was quite a jump.
> ...


Yes, it's a huge difference. This is why I don't participate in threads that ask, "What gear ratio do you use?"... so many people contribute without bothering to mention what wheel size they're running... which is part of the equation. It's meaningless to talk about it unless the wheel size is included.

Of course terrain, distance traveled, fitness level, etc. are huge factors, too.

It's really a pointless discussion. Run whatever ratio you like. Experience is the only thing that can determine this.

--sParty


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## 1SPD (Apr 25, 2010)

Well now that I have been enlightened with the actual equation I feel I can comment here and there but the wheel size is a huge part of it.

I am thinking I am going to try to swap the rings this evening to see what it does for my chain tension. The chain is too long and has my sliders almost all the way back. Removing a link makes it too short even when slammed. This might do the trick short of a 1/2 link.

I love the old Deor cranks when polished up nice and purty but I'm not a fan of the square taper spindles or the weight for that matter.


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## meltingfeather (May 3, 2007)

bikeny said:


> This is not really true. It all depends on what alloy of each material is being used. The Surly rings are made of a very soft stainless, which is much weaker than your standard carbon steel. This is why the Surly rings bend so easily. Unfortunately, Homebrewed (Dan) does not make stainless rings, only stainless cogs. But his cogs are made from heat treated 17-4 stainless, which if very hard and strong, but expensive. I believe that's why he doesn't make chainrings out of this material, the cost would be so high, you would be better off with titanium. Titanium rings can also be made from different alloys. The good ones (like Boone and Homebrewed) are made of 6-4 which is harder/stronger that 3-2.5. Someone else may chime in with the exact details, but that is the jist of it.


I don't see how any of this makes what i said wrong. yield point (strength) varies widely with alloy and also with the degree and/or use of other treatments. the range of yield strengh that you see in steel and ti is about the same, though. elasticity is not affected by these things as much... BUT i didn't really go into that.
my general point was that steel and ti are comparable in performance strength wise, with ti being more elastic (which can adversely change loading in a chainring) and it's primary benefit being weight (_i.e._, you are not automatically going to be less prone to bending and/or failure by using ti). your point about alloys is further evidence for what i said.


bikeny said:


> I am also one of those retro grouches that hates 4 bolts cranks. All of my geared bikes still use 5 bolt cranks. But for by singlespeed, I like the spiderless setup even more.


I'm interested in this... particularly because I'm about to switch from a 4-bolt crank to a spiderless SRAM/HBC set-up. The stress at the ring/crank interface will be MUCH higher in a spiderless set-up, and typically the support a ring gets from a spider has more lateral strength and stiffness than a spiderless ring, so I'm curious why you hate 4-bolt but like spiderless seemingly based on stress and/or support.
I have no doubt that the spiderless set-up will work very well, I'm just curious about how the design affects performance.


bikeny said:


> I splurged for the titanium ring because, well I have a problem!


I stuck with Al this time around because my problem is resisting that sweet anodized red ring! 
I'm going to XO with an HBC 33t and King bottom bracket. I just sold two complete bikes and have a little extra cash lying around, so I wanted to pimp out my ss, which currently has a V-Drive crank with a 32t RaceFace ring.


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## meltingfeather (May 3, 2007)

Sparticus said:


> ATX... after googling I expect you're either in Austin, TX or Atbasar Airport, Kazakhstan.
> 
> I'm not visiting you to go riding if you're in Kazakhstan. Austin, that's more reasonable. Good singlespeeding there?


can't blame you... though i've never been to wherever-stan. i know there's lots of good riding in a lot of places, and austin is a city spoiled with many many many miles of great trails very close to and/or inside the city. TONS of great s'speeding around here.
another benefit is the scenery. there is no denying that we're spoiled with great looking women here.... moreso than most places i've been in the US.  


Sparticus said:


> P.S. I lied. I was jabbing you. Thanks for going along. Seriously. The internet is such a hard place to figure what people really mean. I meant no harm, just kidding. But that can be dangerous ground here.


i KNEW IT!!!
i'm keeping my eye on you. :skep:
all in good fun. i keep internet ramblings in perspective.


Sparticus said:


> I expect we're both reasonable people.


i'd put money on it... unless this is another trick!   


Sparticus said:


> I'm just not as smart as you.


don't know about that... probably depends on what topic we're talking about. believe it or not, i know when to shut up and listen/learn.


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## Spam Me (Feb 28, 2011)

*Does tyre come into it as well?*

I have seen the equations in this thread, should the tyre size be taken into account as well?


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## meltingfeather (May 3, 2007)

Spam Me said:


> I have seen the equations in this thread, should the tyre size be taken into account as well?


It depends on how gnat's @ss you want to get and what your goal is. The answer is usually no.
29" is close enough. If you want to get very precise, you'd have to ask a friend to measure from the axle to the ground with you sitting on the bike with your tires at your normal pressure.
Then what about crank length?
If you want to look at gear inches to get an idea of where to start in gearing or what a certain change will do, the formula presented is fine.
Since I'm always on 29er wheels, all I look at is the gear ratio.
:thumbsup:


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## bikeny (Feb 26, 2004)

meltingfeather said:


> I don't see how any of this makes what i said wrong. yield point (strength) varies widely with alloy and also with the degree and/or use of other treatments. the range of yield strengh that you see in steel and ti is about the same, though. elasticity is not affected by these things as much... BUT i didn't really go into that.
> my general point was that steel and ti are comparable in performance strength wise, with ti being more elastic (which can adversely change loading in a chainring) and it's primary benefit being weight (_i.e._, you are not automatically going to be less prone to bending and/or failure by using ti). your point about alloys is further evidence for what i said.


I don't have the time or energy to go looking up the properties of either material. I believe the strength as well as stiffness vary considerably with different allows. The Surly site says 304, but obviously nothing about heat treating, which effects the mechanical properties greatly. The advantage of Ti depends on how it is used. I am not going to go any furher about this.



meltingfeather said:


> I'm interested in this... particularly because I'm about to switch from a 4-bolt crank to a spiderless SRAM/HBC set-up. The stress at the ring/crank interface will be MUCH higher in a spiderless set-up, and typically the support a ring gets from a spider has more lateral strength and stiffness than a spiderless ring, so I'm curious why you hate 4-bolt but like spiderless seemingly based on stress and/or support.
> I have no doubt that the spiderless set-up will work very well, I'm just curious about how the design affects performance.


The main problem with the Surly rings is they are very thin, probably only 2mm or so. With only 4 suppor points, any side loading will cause the ring to buckle. A 5 arm crank reduces the unsupported distance. As for the crank/ring interface of a spiderless design, yes the stress will be higher. But instead of 4 or 5 points, the stress is spread out over typically 8 to 12 splines. As for lateral stiffness, the spiderless rings usually are made from much thicker material that a standard bolted chainring. Also most of the spiderless rings actually have 5 arms going out to the teeth anyway, mimicking a 5 arm bolted setup. The crank/chainring spline setup has been used for many many years, and I have never seen one striped out. My Boone/XTR M950 setup has been perfect. This setup usually results in a rounder chainring as well.


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## meltingfeather (May 3, 2007)

bikeny said:


> I don't have the time or energy to go looking up the properties of either material. I believe the strength as well as stiffness vary considerably with different allows. The Surly site says 304, but obviously nothing about heat treating, which effects the mechanical properties greatly. *The advantage of Ti depends on how it is used*. I am not going to go any furher about this.


having spent a bunch of time studying materials and TA'ing materials lab (running tests and grading undergrad reports) I've got that stuff somewhat at my fingertips. if you have any questions, let me know.
you have the time and energy to tell me i'm wrong but not to explain why?
my whole point can be boiled down to what i put in bold in your post. except for you saying I was wrong, which you didn't explain or substantiate, we agree on everything. :thumbsup: 


bikeny said:


> As for the crank/ring interface of a spiderless design, yes the stress will be higher. But instead of 4 or 5 points, the stress is spread out over typically 8 to 12 splines. As for lateral stiffness, the spiderless rings usually are made from much thicker material that a standard bolted chainring. Also most of the spiderless rings actually have 5 arms going out to the teeth anyway, mimicking a 5 arm bolted setup. The crank/chainring spline setup has been used for many many years, and I have never seen one striped out. My Boone/XTR M950 setup has been perfect. This setup usually results in a rounder chainring as well.


I know they work (I have the confidence to have ordered the set-up already), and I know there are ways to engineer around trade-offs in a design. sounds like the thickness of a spiderless ring is a key factor. the roundness benefit makes sense because the spider is essentially built into the ring, making the whole more easy to manufacture precisely and less likely to deform.


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## bikeny (Feb 26, 2004)

meltingfeather said:


> having spent a bunch of time studying materials and TA'ing materials lab (running tests and grading undergrad reports) I've got that stuff somewhat at my fingertips. if you have any questions, let me know.
> you have the time and energy to tell me i'm wrong but not to explain why?
> my whole point can be boiled down to what i put in bold in your post. except for you saying I was wrong, which you didn't explain or substantiate, we agree on everything. :thumbsup:
> 
> I know they work (I have the confidence to have ordered the set-up already), and I know there are ways to engineer around trade-offs in a design. sounds like the thickness of a spiderless ring is a key factor. the roundness benefit makes sense because the spider is essentially built into the ring, making the whole more easy to manufacture precisely and less likely to deform.


If you look back at my post, I never said you wrong, I said "not quite true'. Maybe I should have said 'not quite that easy'. I also never said using Ti would automatically make a ring less prone to bending. As far as keeping rings from failing, I believe the strength (Ultimate tensile strength?) has a lot more to do with it than the flexibility. If you have the numbers at hand, please post them! I would like the see the numbers for 3-2.5 & 6-4 ti, 304 & 17-4 stainless. I guess for the 2 steels you would need numbers for heat treated as well as not.


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## meltingfeather (May 3, 2007)

bikeny said:


> If you look back at my post, I never said you wrong, I said "not quite true'. Maybe I should have said 'not quite that easy'.


Since you're quoting, you said "not really true," but that doesn't matter, except that I still don't understand what you think is not true. From here it looks like we agree across the board.


bikeny said:


> I also never said using Ti would automatically make a ring less prone to bending.


And you aren't who I quoted. If you look at what I quoted, that is what was said, and I said *exactly* the same thing you eventually did: the benefit of Ti depends on the design (_i.e._, it's not automatic).


bikeny said:


> As far as keeping rings from failing, I believe the strength (Ultimate tensile strength?) has a lot more to do with it than the flexibility.


It's yield strength, not ultimate, and I think that you're right, *BUT* the flexibility allows a ring to get out of perfect alignment and start seeing loading that's not in the plane of the ring... that was also kind of central to my point.


bikeny said:


> If you have the numbers at hand, please post them! I would like the see the numbers for 3-2.5 & 6-4 ti, 304 & 17-4 stainless. I guess for the 2 steels you would need numbers for heat treated as well as not.


It doesn't work like that and I don't have time to explain it in detail, but here's a quick-and-dirty for you:
Steel and ti have about the same yield strength, and the range of yield strength is also about the same (the weakest steels are about the same as the weakest ti, same for the strongest). Alloying, heat treatments, and cold work can all affect this, and it's not just black-and-white (_i.e._, heat treated or not), the process and degree of each can significantly affect the result (it is spectral rather than on/off).
Ti is about twice as flexible as steel. Alloying and cold work don't really change that (all steels have the about the same elasticity). Heat treatment doesn't really either.
Ti weighs about 60% of what steel does.


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## JeffL (Jan 25, 2009)

meltingfeather said:


> ...
> Then what about crank length?
> If you want to look at gear inches to get an idea of where to start in gearing or what a certain change will do, the formula presented is fine.
> Since I'm always on 29er wheels, all I look at is the gear ratio.
> :thumbsup:


Of course, crank arm length does make a difference. Changing crank arm length 10mm has almost exactly the same effect as changing one tooth on the rear cog. That's the reason I'm a fan of Sheldon Brown's gain ratio calculation instead of using gear inches.

http://sheldonbrown.com/gain.html

For people that have spent years using gear inches and thus have a quick idea of what a particular number means, I can understand the resistance to switching to a different system. But for me, I discovered the gain ratio at about the same time I discovered singlespeed and never used gear inches much. So the gain ratio numbers are just as meaningful to me as anything else, and a bit more informative.


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## meltingfeather (May 3, 2007)

JeffL said:


> Of course, crank arm length does make a difference. Changing crank arm length 10mm has almost exactly the same effect as changing one tooth on the rear cog. That's the reason I'm a fan of Sheldon Brown's gain ratio calculation instead of using gear inches.
> 
> http://sheldonbrown.com/gain.html
> 
> For people that have spent years using gear inches and thus have a quick idea of what a particular number means, I can understand the resistance to switching to a different system. But for me, I discovered the gain ratio at about the same time I discovered singlespeed and never used gear inches much. So the gain ratio numbers are just as meaningful to me as anything else, and a bit more informative.


unless you're changing crank length regularly, accounting for it is just an added unnecessary component of the equation.
i don't ever change wheel size, so i don't multiply everything by 29" either, i just look at the straight gear ratio if/when i do.
i don't do a lot of calculating gear ratios, though, i just ride with different cogs and go with whatever feels best at the moment.


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