HELP! BB/crank just locked up?!?!
 

My buddy has 1988 Trek 1000. The other day we were out on a ride and all of a sudden it was like someone applied both brakes. He could barley pedel. The crank will not turn by hand but will turn if forced with your feet. What might have caused this? We haven't torn into it yet but I'm thinking its the bearings in the BB?

It probably has caged bearings, and a piece of the cage cracked off and wedged itself between the balls and the races. The cages are usually softer metal, so hopefully the races have not been messed up. I used to see this all the time when I was a shop monkey back in the 80's

Or maybe a cup has backed out and tightened up against the back of the crank arm.

my guess is the freewheel is done.

remove the chain and see.

Cracked ball or busted cage, would be my first thoughts, if it is indeed the bottom bracket. I have my doubts that the freewheel would be the culprit, but dropping the chain off the the crank rings would be the first place to start your trouble shooting efforts.

The freewheel would have probably thrown the chain. Most likely is bearings or cage.

If the lockring is loose, epicyclic action will cause the adjustable cup to self-tighten.

He txed me a photo last night at home. It looks as though the cage in the non-drive side has backed out. I'll see for myself today.

I'm trying to make sense of that.

Ok, here's the deal. His non-drive side bearing cup backed out and is cracked as well.

time to get a new BB, and check the BB shell on the frame to see if its cracked.

What do I win?





:D

A free life time supply of condements from Burger King. Just tell them I sent you.

Lol

You can pack the bearing of the new BB with the mayo :)