Crank Arm Issues
11-09-10, 07:23 PM
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Crank Arm Issues
Hey I have been borrowing a single speed from friend for a little while and its having some issues. He built it by the seat of the pants it seems. Its a basic Nishiki sport.
One problem. The left crank arm keeps working its way off of the bottom bracket. I replaced the crank arm for him once, but even after tightening that allen bolt down good and tight, it still worked its way off. Before it comes off, it makes an un common creaking sound as well.
Should I grab a plastic hammer and tap it in there before tightening the allen bolt? Should get a crank arm with a square slot thats just a hair smaller? Or is it the bottom bracket?
Thanks for the help if you can offer it.
One problem. The left crank arm keeps working its way off of the bottom bracket. I replaced the crank arm for him once, but even after tightening that allen bolt down good and tight, it still worked its way off. Before it comes off, it makes an un common creaking sound as well.
Should I grab a plastic hammer and tap it in there before tightening the allen bolt? Should get a crank arm with a square slot thats just a hair smaller? Or is it the bottom bracket?
Thanks for the help if you can offer it.
11-09-10, 07:34 PM
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Don't tap it in, use proper tool.
Crank arm needs a really high torque that a flimsy, short Allen key can not produce. Use a long ratchet wrench and an 8mm Allen key socket.
Crank arm needs a really high torque that a flimsy, short Allen key can not produce. Use a long ratchet wrench and an 8mm Allen key socket.
11-09-10, 08:01 PM
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It's not likely and you'll need that much torque to secure the crank arms in place.
You should clean and grease the threads before installing it next time; however, your crank arm/bottom bracket might have been rounded out from the constant falling.
You should clean and grease the threads before installing it next time; however, your crank arm/bottom bracket might have been rounded out from the constant falling.
Last edited by Squirrelli; 11-09-10 at 08:24 PM.
11-09-10, 10:44 PM
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I installed my cranks with the 8mm on my pocket multi-tool about five or six months ago. Hundreds of miles on them and no problems yet. For the record, I don't recommend this, I just think something is whacked on your setup. Securing a crank-arm isn't too difficult.
11-10-10, 06:27 PM
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^^^ This. It happened to me. It sucks, but the opening in your left crank arm is most likely malformed. Take it off and check it; I bet you'll find marks where the corners of the bottom bracket spindle have dug into the flat lines of the square-shaped opening. About all you can do is replace it and remember to check torque frequently from now on.
11-11-10, 10:50 AM
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sounds like that crank arm has done its last turn XP
https://sheldonbrown.com/brandt/installing-cranks.html
https://sheldonbrown.com/brandt/installing-cranks.html
