Wheelbase effect on Cornering......

lorrod said:

Does anyone know if there is a correlation between wheelbase length and cornering on a road bicycle? For instance, if the wheelbase length on a 56cm frame is a bit longer than on another 56cm frame, will this effect the handling of the bicycle in corners?

There are a number of other factors that need to be considered as well, such as seattube/headtube angles and trail of the fork. If (and that's a big if) all else is equal then in general a longer wheel base is more stable & one with a shorter wheel base tends to be more maneuverable.

lorrod said:

Does anyone know if there is a correlation between wheelbase length and cornering on a road bicycle? For instance, if the wheelbase length on a 56cm frame is a bit longer than on another 56cm frame, will this effect the handling of the bicycle in corners?

To a physicist-yes.
To the person on the bike-no.

ed073 said:

To a physicist-yes.
To the person on the bike-no.

All else being equal, the front wheel on the longer bike has to be turned more to be tangent to the same turning radius as the front wheel on the shorter bike. Inversely, a given disruption in steerer tube angle puts the longer bike into a larger radius turn. That's where the more stable feel comes from. Of course if you're going in a straight line, the turn radius is infinite, and the difference is negligible. As the turn radius decreases, the effect is magnified.

I have two road bikes with identical geometry aside from an extra centimeter of length in the front triangle on one of them. There is a considerable difference in feel. The longer bike is a bit more stable, but also has some understeer going into hard corners.

Art what is your impression of steering turn in due to altering stem length which has been often mentioned. I ride a big bike which tends to be pretty stable...can go no handed on it...and just changed from a 130mm stem to a 100mm stem and honestly the bike doesn't steer much differently. My impression is the wheel base, trail including fork rake and steerer tube angle have more of an effect on turn in and straight line stability at speed as opposed to a stem length change.
Curious if others agree?
George

biker7 said:

Art what is your impression of steering turn in due to altering stem length which has been often mentioned. I ride a big bike which tends to be pretty stable...can go no handed on it...and just changed from a 130mm stem to a 100mm stem and honestly the bike doesn't steer much differently. My impression is the wheel base, trail including fork rake and steerer tube angle have more of an effect on turn in and straight line stability at speed as opposed to a stem length change.
Curious if others agree?
George

In theory, a longer stem will give you less roatation for a given bar displacement. However it also changes the direction of the displacement. It will be almost completely fore-aft for a 0mm stem, and completely side-side for an infinite stem. Obviously neither of those is realistic, but from an ergonomic stanpoint the path of motion matters as much as or more than the amount. In the end, there's no hard and fast geometric correlation between stem length and stability, and it all comes down to personal preference. I've heard a lot of people say that they feel anything less than 110mm is too twitchy. Other people feel comfortable all the way down to 90mm.

An interesting perspective Art contrasting an infinite versus stem without finite length. I would add to your comments that steerer tube angle and fork rake are the "second stem" in the equation so it is the ratio of both that matters over and above the wheel base of the bike in terms of twitchiness. To use your extreme analogy...don't know if you have ever ridden an extended fork chopped motorcycle. Independent of bar offset up top which you could say is the same as a stem...a chopper takes forever to turn. In part due to wheel base but in large measure due to fork angle as only the cosine of the steering angle including steerer tube and fork rake turns the axis of the front hub. Fork rake which includes the radius of the fork and steerer tube angle introduces caster or returnability to the steering for straight line tracking analogous to the king pin angle on a car. A lot of people don't know what caster is and what it does. Caster in effect induces physical lifting of the bike against its own weight based upon the horizontal component of fork rake...hence its self centering tendency. Believe with my tall and long wheelbase bike that is why changing stems from 130-100mm has a modest affect on steering sensitivity. May not be the case with a smaller bike with smaller wheelbase and shorter horizontal distance from top of steerer centerline to hub axis.
George