Chainstay length and wheelbase

Vitamin G · Sep 20, 2010

I'm trying to do some research on frame geometry, in hopes of getting a new bike in the next year. Currently riding a Trek 2100, which I pretty much like. So, I'm doing a bunch of comparisons on geometry, and pondering what differences a few mm will make here and there. A lot of the bikes I'm dreaming about right now I can't test ride at the moment, so this is all academic.

My Trek has a chainstay length of 417mm, and a wheelbase of 994 mm. One of the other bikes I am interested in is a Gunnar Roadie, which has a chainstay length of 410 and a corresponding wheelbase of 988 mm. How much "quicker" will the Roadie be with a 6mm shorter wheelbase? Is that difference too small to be felt? The other specs on the bikes look pretty similar, but trail is 1mm more on my Trek (55 vs. 54).

So, how much difference in chainstay length is enough to feel the difference in handling, given the same headtube angles?

Peter P. · Sep 20, 2010

I personally don't think chainstay length affects the quickness of handling that much because as you've discovered, differences between brands is measured in millimeters and most road bikes fall into a narrow range of roughly 408-415mm. Beyond that you're talking about a different kind of bike such as cyclocross or touring. Also, shorter chainstays are not necessarily better, so don't get wrapped up in seeking the shortest possible rear end.

If quickness of steering is your main concern, look more closely at head angle and fork rake.

orange_julius · Sep 20, 2010

Peter P. said:
I personally don't think chainstay length affects the quickness of handling that much because as you've discovered, differences between brands is measured in millimeters and most road bikes fall into a narrow range of roughly 408-415mm. Beyond that you're talking about a different kind of bike such as cyclocross or touring. Also, shorter chainstays are not necessarily better, so don't get wrapped up in seeking the shortest possible rear end.

If quickness of steering is your main concern, look more closely at head angle and fork rake.

Ditto on head angle and fork rake, those will have more impact than the 6 mm of wheelbase difference.

Another factor to look into is the BB height. Changes in vertical dimension of center of gravity has quite an impact on a bike's feel and handling.

Vitamin G · Sep 20, 2010

I'm glad to read these kinds of replies. I'm not looking for a "quicker" handling bike. Not racing crits, but doing fast training rides and the occasional road race (I do more mtb racing than anything), so I want more of a stage race geometry.

I'll check out the BB heights on the frames I'm interested in.

Thanks.

mtbbmet · Sep 20, 2010

For the record, if you take two frames with the same TT and same CS length the only way to change the wheel base is to change HTA and/or rake. A 1cm difference in wb makes a huge difference in ride feel. Most CS lengths are between 405 and 420, but the common number is 410ish. Which really makes the major variables HTA and rake. A 5mm difference in rake, or a 0.5' difference in HTA can substantially affect the way a bike rides.

Kerry Irons · Sep 21, 2010

Length matters

Vitamin G said:
So, how much difference in chainstay length is enough to feel the difference in handling, given the same headtube angles?

As others have noted, chainstay length will not be a big factor in handling quickness. However a shorter chainstay (all else equal) will give a rougher ride because it moves the rear wheel more under the saddle. Because of this, any vertical bumps from the wheel hitting something will be more directly transferred to the saddle. There are a lot of other factors, and 7 mm is not a large change, but that is more likely to be noticeable than quicker handling.

Chainstay length and wheelbase

Vitamin G

Peter P.

orange_julius

Vitamin G

mtbbmet

Kerry Irons

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