High speed wobble/shimmy
#1
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High speed wobble/shimmy
I was on a ride today going downhill. Occassionally, I applied both the back and front brakes to slow. At one point the bike began shaking violently. I thought first I was going to crash and I thought the cause might be a flat. I braked slowly and just prior to stopping the wobble went away. I checked my max speed and it was around 42 MPH.
I was in the drops at the time. I've gone faster without a problem. The road was fairly new chip seal. This was the first ride I've done since moving the seat back. I have ultegra brakes. I didn't notice any wobble in the tire, just the whole bike shaking. It did seem to be the front tire.
Any ideas what might have caused this?
I was in the drops at the time. I've gone faster without a problem. The road was fairly new chip seal. This was the first ride I've done since moving the seat back. I have ultegra brakes. I didn't notice any wobble in the tire, just the whole bike shaking. It did seem to be the front tire.
Any ideas what might have caused this?
#2
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You hit the right speed in the right conditions that caused the bike to vibrate. You can either speed up, slow down, and/or press your knees against the top tube to reduce/remove the vibration.
#3
Banned
side effect of light, flexible, frames .. Dynamic balancing is done to Motor bike wheels
not bike wheels ,
ready to have an absolutely perfect frame/ fork alignment job done?
[only really practical cold setting steel.. ]
Or, You might just want to keep your speed down , in the future ..
not bike wheels ,
ready to have an absolutely perfect frame/ fork alignment job done?
[only really practical cold setting steel.. ]
Or, You might just want to keep your speed down , in the future ..
#4
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At a guess, moving the seat back means you now have less weight on the handlebars, which creates less damping in the steering. Read on:
https://www.sheldonbrown.com/brandt/shimmy.html
https://www.sheldonbrown.com/brandt/shimmy.html
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Any ideas what might have caused this?
One way to minimize shimmy while coasting, is to put one's knees together.
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As unreasonably doubtful as this may sound, check the rear wheel first. Also, check for any suspicious frame anomalies... again, focusing on everything from the seatpost and back.