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Perfect chainstay length

7K views 14 replies 13 participants last post by  eri 
#1 ·
Just wondering if there are any ideal chainstay lengths for a single speed.

I run 20x32 and feel like I can never use the adjustable dropouts on my bikes. Most recently my last bike had a min chainstay length of 445mm and my current bike is 427mm. Even though they both have adjustable dropouts there is only 1 rand9m position in the sliders that works with single speed chain. If i take out a link the chain is way to tight and if I add a link then I can't tension the chain
 
#2 ·
Those adjustable dropouts aren't there to change your chain stay length, they are there to tension your chain properly. That said, there is no idea chain stay length. It's a number that results typically from arriving at working solutions with other parts of the frame's geometry. A longer chain stay will result in a more stable ride, a shorter one in a slightly more playful ride. Some people complain you can't manual a bike with long stays, but I've never had that problem, and I've ridden (and owned) some of the worst "long chain stay" offenders, to hear some of the folks on MTBR have their say. I suppose the question is, do you feel confident in your bike at high speeds? Do you feel like you can't make your bike do the stuff you're asking it to do? Is there some glaring deficiency? Because "ideal" is going to come down to your opinion of how the bike rides.
 
#4 · (Edited)
my perspective is- the shorter, the better. sub-17" (~430 mm) chainstays are nice, but under 16.5" (~420 mm) might be ridiculous. but that's my subjective experience based on my height, weight, and riding style. other riders will want them much long and others much shorter.

on any bike that uses adjustable sliding dropouts to tension a chain, you get what you get with the gear combo you chose. so if you think you have the "perfect" number in your head, you're going to be off by a little bit in the real world.

also keep in mind- CSL cannot be taken in isolation. if you want to make the front end of your bike easier to loft, shortening the CSL is one way, but raising the BB, or shortening the reach to the bars can have a similar effect.

a bike with a low BB and a long CSL is going to feel very stable, and might be preferred if you're tall, or if you're riding long distances with a loaded bike.

but a long CSL with a very high BB might balance out. a high BB and a short CSL will be nimble indeed, maybe too much so, such that it will loop out and cause you to go OTB often. there's a balance and compromise to seek here.

it is my opinion that a bike with a low BB ought to have a comparatively short chainstay as well, at least for the way I like my bike to handle.
 
#15 ·
Nice post.

Besides ease of lofting front the shorter chainstays mean more weight on rear tread while climbing steeps, i can get max grip with a natural stance on bike. With long csl theres less weight on rear and i must hurk back on bars or the rear wheel slips. And slipping rear wheel while climbing is no fun at awl.
 
#5 ·
I run 30x18 on my Nimble 9, and I've run the dropouts both almost fully extended (~430mm) and almost fully slammed forward (~415mm). Adding or removing two links causes those results.

I was surprised how much difference 15mm could make in the way the bike rides. The longer the chainstay, indeed the stabler the bike is at speed. Likewise, the shorter the chainstay, indeed the more "nimble" the bike is in general.

Overall, though, I'd agree with above. The shorter the chainstay the better. Less chainstay = Mo' fun.

Find the ratio you like to run, then try a few different chainring/cog combos with that approximate ratio that will allow the shortest chainstay.
 
#9 ·
It sure looks like you could use the dropout to tension the chain but the only draw back is a lack of anything to lock the adjustment in, it might slip(it's also possible they have no clue what you're talking about). Being a steel frame though you should be able to get some good torque on those screws. If the 411mm stated chainstay length is in the slammed forward position(which the drawing seems to indicate), the next sweet spot looking on the eehouse fix me up site(https://eehouse.org/fixin/formfmu.php) is at about 415-416mm which should work nicely.
 
#11 ·
nsbikes.com said:
MAIN FEATURES:
- designed for All Mountain, Freeride
- high-end cromoly steel tubes
- modern aggressive geometry (slack HA, low BB, long reach).
- adjustable CS lenght via sliding dropouts
I wonder if they mean it doesn't have enough adjustment to guarantee fitting a particular gearing.
 
#14 ·
There looks to be plenty there to tension and you also don't really need a jam bolt to make it work, although you may find yourself tensioning the chain a *little* more than normal.

I'd go into it prepared to need to try a couple different cogs in case my gear choice was at the extreme end of being long or short, but aside from that it will be fine.
 
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