Bike Shake

[senator52]

I was recently given an old roadie by a friend leaving the country, this was much appreciated since i had snapped the frame of my other bike recently and whilst at uni do not have a budget however the first time i got out of the saddle to give it a real sprint the frame started to vibrate viciously and i had to stop the sprint. I was wondering what would attribute to this? I do know that the wheels are not true and that the frame is too small, but would this indicate that the frame is not straight? Thanks.

[AUbicycles]

I have the feeling that it has something to do with the wheels which are unbalanced - either not trued or the forks / drop outs are not aligned meaning the wheel is not sitting straight.

Have you tackled any hills where you get the same speed as when sprinting? You can probably work out when sprinting if the problem is more at the front (really shakey handlebars) or coming from the rear wheel.

If the problem is with the frame and it is an old steel frame it can (in theory) be bent back into place... to get it done properly though it may cost a few dollars so you would have to weigh up the costs. BTW, if you take it to a bike shop be very specific about the task they should work on. One bike did the gears on a roadbike of mine but told me that the frame wasn't worth the cost of straightening. Of course they wanted their 'workshop fees' for a bike which I couldn't ride and for which I didn't ask them to tune. I complained to the manager and was rightly not required to pay the fees.

Cheers
Christopher

[senator52]

Well i think it is coming from the front...i have tackled a few rather large fast descents and it does not seem to shake. Just when i get out of the saddle it just seems to have a mind of its own=( the handling itself from the bike on a whole may be described as "inconsistent". Is there anything i can do atm to fix this problem? Or should i just enjoy putting in some k's til i get outta uni and into some cash...thanx.

[Mulger bill]

The headset might need adjusting.

Try wrapping your left hand around the top of the fork/bottom of the head tube, lock the front brake, then rock the bike forward and backward. If you feel movement or clicking, it's the headset.

[mikesbytes]

It could be anything. Your going to have to check everything. I'd start with anything that is potentially a saftey issue, ie something breaking. Check the entire bike front and rear for cracks, loose anything etc. I'd even take the forks out and check the steerer for cracks.

Have a nice day
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