The nut that holds the pedal arm (not sure what the correct terminology here is, sorry) keeps coming loose every few days. I tighten tf out of it and it’s good for a bit but inevitably comes loose again.
I am a larger/heavier body on this thing so not sure if it’s that or if it’s the age of the bike maybe?
Thanks in advance for any insight
by TommyTwoFlushes
8 Comments
Assuming you tightened them correctly. The crank has to be replaced due to the hole, wich in this case is meant to be square Will now be oval or rounded
Tighten it to 40 Nm and you won’t need one.
If it keeps happening, then you likely have an issue with the crank arm.
My thought is the crank arm hole or spindle are damaged and that’s allowing the crank arm to wiggle and either loosen the nut or continue to get damaged.
I’d try tightening and marking it with a grease pen if you have one to make sure it’s the nut loosening.
You need a new crank arm. Go to your local bike shop. They will press the old on off and install a fresh. The square hole of the crank arm starts to round and you’ll never get it to stay tight.
No, should be tightened sufficiently though to correct torque
You could try blue loctite (the removable kind) on the bolt AND on the axle. Make sure you clean any grease off the threads and axle and the inner part of the crank arm where the axle mates so it is clean bare metal. Then tighten it as hard as you can. IF that doesn’t work then you probably need a new crank arm as others have said.
Thanks everyone!!
That’s an interference fit, it has to be torqued to 35 foot pounds. If you ride loose the precision machines square taper gets stripped and you need a new crank arm. It sounds like you have entered the new crank arm portion of the repair.