I've recently test rode 3 different road bikes down a fast, curving descent and experienced a shimmy as I approached 35 - 40 mph. Two of the bikes were titanium and one was steel. On my current aluminum frame, I take the same descent at 48+ mph and always feel in control. I did feel that I had a longer/lower reach to the bars on the demo bikes.
How can I best determine a proper, well centered riding position? What are the more common frame geometry differences that may account for such a dramatic change in handling?
I've recently test rode 3 different road bikes down a fast, curving descent and experienced a shimmy as I approached 35 - 40 mph. Two of the bikes were titanium and one was steel. On my current aluminum frame, I take the same descent at 48+ mph and always feel in control.
what make is the aluminum frame? what diameter tubes does it have? what size is it?
Shimmy is apparently a part of the intrinsic geometry of some bikes. If you shift your centre of gravity you can stop it. Read Jobst Brandt on it in the cycling FAQ
Shimmy is apparently a part of the intrinsic geometry of some bikes. If you shift your centre of gravity you can stop it.
I think I dispelled that in a number of tests (riding no-hands) leaning back leaning forward and making no change in the shimmy that occurs naturally with my bicycle if I allow it to do so. Tests were also done with balanced and unbalanced wheels as well as one filled entirely full with water to see what rotating mass had to do with it. These all had no effect on initiation of shimmy.
jim beam <[email hidden]> wrote in message news:<[email hidden]>...
Quoted message said:
Quoted message said:
I've recently test rode 3 different road bikes down a fast, curving descent and experienced a shimmy as I approached 35 - 40 mph. Two of the bikes were titanium and one was steel. On my current aluminum frame, I take the same descent at 48+ mph and always feel in control.
what make is the aluminum frame? what diameter tubes does it have? what size is it?
jb
My aluminum bike is a GT ZR4.0 - 52cm. Tubes are oversized with rather unique shapes...relatively stiff. The Litespeed Siena was a Med.(53) and the Litespeed Vortex was a 55cm. I felt better situated on the GT, and wonder if I'll get as comfortable once I dial in position on a Litespeed. Thanks.
