Bicycle Mechanics - Wobbly Crank

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askrom

10-01-05, 09:45 PM

I'm able to, using my hands alone, wobble my crank arm about 1/8" to the left and right. I can only guess what this means for my riding performance, but I imagine it explains why when I pedal really hard my chain scrapes my front derailleur no matter how I fine tune it (it's non-indexed).

Does this mean that the bottom bracket isn't adjusted properly? Or, worse, that the BB is shot? My setup is about 12 years old.

slagjumper

10-01-05, 10:00 PM

If both arms move it is the BB. If it has been that way for a while you probably need a new one. If only the gear side crank arm moves maybe all you have to do is tighten that side. Does the crank us a cotter pin or 14or15 mm center bolt? Avoid riding it untill you can get it fixed.

Portlandonian

10-01-05, 10:21 PM

If it's a standard sized bike I would just buy a new BB, they really aren't that expensive, or just new BB bearings.