Bicycle Mechanics - Shaky Cranks

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tansc
04-04-05, 07:48 AM
Hi

I have a relatively new bike (about 3 months old), and have a problem..the left crank arm and gears are a little shaky (but the right arm is relatively stable), and when I use higher gears, the chain tends to scrape against the gearshifter when the arm is shaken around in a particular way...

Any suggestions?

Tsc

powers2b
04-04-05, 08:21 AM
Take it back to the LBS and have it adjusted.
If you bought it at a department store then get a 14 or 15mm socket wrench and tighten the crank bolt. (you will have to remove the dust cap first).

Enjoy
MichaelW
04-04-05, 08:23 AM
It could be a number of things:
The crank is lose on the bottom bracket spindle.
The spindle is lose in its bearings
The whole bottom bracket part of the frame is flexing under pedalling force.
The shop should be able to sort out any problems on a 3-month old bike.

Ya Tu Sabes
04-04-05, 08:28 AM
If it's only one side, it's probably not the bottom bracket itself that's loose; more likely the crank bolt or maybe the chainring bolts. But I agree, let the shop worry about it.
Metro
04-04-05, 09:41 AM
Bolts/nuts/screws, etc come loose over time, especiall on new bikes. Most bike shops have a policy of free post ride adjutments because they know this happens. I screwed up/chewed up the crank arm on the first bike I owned years ago for that very same reason. I concur with everyone else. Take it back to the shop where you purchased it and have them tighten it up. If they won't service you, it is time to find another bike shop.

Good luck.