Chain Escaping From Jockey Wheels

pirnie

Hi All,

I was out on a ride on Saturday, and at one point when I changed gears there was a crunch and the chain stopped turning.

I stopped to have a look, and much to my amazement the chain seemed to have skipped round top jockey wheel in the rear mech and was running from the cassette straight into the lower jockey wheel. Upon closer inspection this was able to happen because the bolt holding the top jockey wheel to the back plate of the mech had come undone.

Luckily all the parts were there and I could fix it and carry on with my ride, but is there anything that could have caused the jockey wheel bolt to loosen like this, or is it just a case of I should have checked it was tight or put some threadlock on it?

Cheers in advance!

keef66

Never heard of that happening before! When I've taken mechs apart in the past I've noticed that the pulley mounting bolts had blue thread lock on the threads that screw into the inner side plate, so it may be a sensible precaution to add a bit more on reassembly.

Monty Dog

Make sure they're tight - as there's no secondary thread-locking, then some Loctite on the threads is a good idea. Not that uncommon - at least you found the parts!