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resolvedHey,
rather unsettling problem started tonight, as i was cruising down hill near the end of my run i took my hands off the bars to sit up and they started to shake, this quickly and alarmingly built up, but couldnt be felt once my hands were back on the bars.
Ive had a good poke round google but cant find anything, maybe im using the wrong term?
help pls!!
A quick and obvious answer is that it's likely to involve the headset, stem, fork or front brake or wheel...
was it just the bars shaking? was the wheel wobbling? was there a noise? were they shaking laterally or vertically?
A quick test to see if there's a problem with your headset is to stand over the bike, hold the front brake on tight and then give the bars a little push forward. There shouldn't be any "give" in the headset and the whole bike should rotate around the front hub, with the wheel nicely on the ground.
the headset is solid, its both wheel and handlebars shaking. Ive never seen this before. I did hit some pretty hard potholes at speed but nothing out of the ordinary, bike is about 6 months old.
front rim true?
any cracks in the fork?
front hub spinning smoothly?
any front spokes loose?
front brake binding?
Is it a solid or suspension fork?
carbon forks, too dark to check out but i think it would be obvious if it failed. front rim, axle and brakes are true and unencumbered. no loose spokes...
its like when your in a car and the wheel balance is off, the wheel starts sawing side to side by itself and the oscillations grow.
In which case perhaps you were cycling on rumble strip. Or you need to cycle with your hands on the bars :) (or failing that, if it happens again, it's a wee tgrip to the bike hospital)
or something blatantly obvious like quick release not done up properly...
thanks for the advice, ima look some more inna morning.
its like when your in a car and the wheel balance is off, the wheel starts sawing side to side by itself and the oscillations grow.
It's not uncommon, and it's called shimmy. Your bike frame is a spring, not a completely rigid structure, and certain combinations of mass (you, plus or minus any luggage) and distribution result in specific natural frequencies of vibration. Usually the remedy is to damp the oscillation by standing on the pedals, or laying your leg against the frame, or another change from the excitation position. Both my old Tange Prestige steel-tubed mtb and my True Temper steel SWB recumbent have springy frames that vibrate maddeningly if I ride no-handed with my panniers loaded out back.
Check out Part 4, Section 8h.5 of the rec.bicycles.tech FAQ for Jobst Brandt's take on it.
thought it might have a name, Thanks. :) I was going pretty fast.. gyroscopes, eh?
great link btw.
although he is wrong about continuously variable transmissions
I was going pretty fast
Consider this is your ticking off for riding no handed while going fast :)
I dont think it was 20mph tho (no speedo) and have you TRIED going no hands slowly? it really hard!
<-- is also a unicyclist :P
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