Chainstay Geometry In General

[Tommy d]

[background story: My frame snapped today, need a new one, considering a custom steel frame as an option for my replacement frame.]

edit: Scroll down a bit, I'm just after some info about chainstay lengths in general now

I'm in need of a new frame and I don't want to have the vertical dropout + tensioner setup that I've been running, because I keep on landing on the tensioner and breaking the mech hanger

I could just get horizontal dropouts, but I'd rather not because of the fuss every time you take the wheel out/put it back in.

My question is, is it a feasible solution to build a frame with vertical dropouts where the length of the chainstay is designed exactly so that the chain fits perfectly on the cogs without needing something to tension it? I know I'll be running 22t front and 18t rear so theoretically this should be possible? Anybody tried it? Does chain stretch mess it up or is that too small a difference?

Edited December 22, 2006 by Tommy d

[Orgun_Donor]

From experience of horizontal drop outs, chain stretch is more then noticable, also if you were taking the wheel out ever time you may encounter trouble with the chain.... maybe.

Id say just get horizontal drop outs, after a bit of practice, its east setting up your drop outs, and can get it spot on every time, even with chain stretch.

[ollie2000]

381 mm should do it i think for a stock

[RobinJI]

Yep, sounds right I think. Until your chain stretches the tiniest bit and flaps around. Seriously, you would be replacing your chain every 3 weeks minimum. Horizontals are fine, its no fuss getting it in or out at-all. The only difference is that you have to take the chain off the sprocket first, which is easy once you put the wheel right forward, and that you have to get it straight putting it back in, which is easy with practice and a well made frame.

[Walleee]

What is all this fuss about?

For a year now i've been riding horizontal dropout's and have NEVER had issues with having to re-align brake's when I take the wheel out or chain stretch which can't be sorted by one click of the snail cam on each side.

I just don't see the problem really.

[Damon W]

a mate of mine has an 06 pitbull with 16.14 gear ratio, and runs no mech...the chainstays are 375 mm and hes been running the chain for a while now and its still tight..

altho if youre running a different chain it will alter, i tried doing it with my khe chin and it was a tad to tite, si the links on a khe must be shorter then the kmc kool :ermm

375mm chainstays are the perfect length too....not too long (still mint for keeping massive drop gaps to backwheel) but not to short to make taps shit

[Martin Grainger]

is it posible to run snailcams on stock-mod frame?

if so that might be a option, ive landed on mine plenty of times and its still fine...

[damon]

There is no bigger problems with removing wheel from frame with vert dropouts and no chains tensioner - i`d say it`s more comf than with mech changer

And 22:18 will fit with 385 (i`m sure, tested) and i think it will also work on 375

btw: have You thought what happen when You decide to change gear ratio?

[Tommy d]

Ok thanks for replies people. I'll probably go for horizontal dropouts, I was just interested.

Now to re-use the topic for my next little investigation:

How long are chainstays generally? I really don't know too much about frame geometry. I know you get long ones and short ones, so how much variation is there?

And somebody please remind me what differences chainstay length makes to riding?

Thanks

[chrishayton]

short stays make the bike better on the backwheel. however too short and they become twitchy and and on long wheelbase bikes the reach can sometimes be an issue. Go with 380mm on a stock and you ll be fine.

[RobinJI]

Hey, I'm riding a custom Iolo that I got horizontals up on. Just as a tip, when you pick the chain-stay length you want, get the company to make that the rear end length when the rear wheel is pulled back about 10mm in the dropouts, otherwise if you need to get the chain off, or you change gear ratio, you have the option of adjustment forwards as well as backwards. Also, if you do this make sure the break mounts are positioned for the wheel to be where you want it, not at the front of the dropouts.

My bike is a 1040 wheelbase, with a 380 rear end how I ride it, and how the break mounts are setup, But if I slam the wheel right forwards in the dropouts, then it becomes a 1030 wheelbase and 370 stays. It just makes things allot easier to set up having some adjustment forwards as well as backwards.

[Glass]

you want vertical dropouts and no deraileur? Do what some single speed bike frames do get an eccentric bottom bracket. Like that you adjust the chain tension at the bb rather than at the chainstays and avoid thus affecting the brake position. Dunno if Iolo will make this though.

http://www.mtbr.com/faq/ssfaq.shtml#ssEbbDefined

[attachmentid=8884]

Another solution would be this:

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Edited December 22, 2006 by Glass