[M.Barcadero]

:madman: I am building a commuter for my 5'4" daughter. I found a straight aluminum MTB bike, have no idea what the frame is (Bad repaint) and I am stripping it to give it a nice couple of coats. It has an OK Alvio Triple, but the crankarm on the left/non-drive side has stripped pedal threads. It is a 170 mm Shimano FC-MC10. Can I just use any 170mm arm? Should I replace both sides? She'll never notice..............

 

[derby]

The crank arm must match the BB spindle. You might get lucky and find one used arm to fit at a bike shop. Alivio has been around a long time and used both square taper and octa-link BB (splined). Determine which BB type and call around.

The cranks are sold new as full sets with new rings now days. Example:

http://www.jensonusa.com/store/product/CR307A02-Shimano+Alivio+Fc-M410+Compact+Crank+Set.aspx

Edit: I should add that if you use a new crankset the chain may be too worn to pedal without skipping and be unridable. Then if you get a new chain, you'll need a new cassette too to avoid skipping in those gears. So if it skips you could put your old rings on the new cranks to get it rolling for a while and replace the chain and cassette later.

 

[mtnbiker72]

Most arms will work but a Truvativ will not due to the orientation of the square hole.

Here is a cheap left arm that will work

http://www.jensonusa.com/store/product/CR408Z21-Sugino+Xd+Crank+Arm.aspx

 

[wyatt79m]

this is a good example of how awesome MTBR can be.
1st post and he got some good useful info.