[kirrill]

Howdy.
my gf has an old trek bike, and here's the problem - which frankly i haven't tried to fix yet.
When she cranks the pedals, going uphill or in high gear from the dead start, the cranks skip about half a turn. Chain does not jump from one gear to another, which makes me thing the allignment is proper, but the cogset is either loose or worn.

Any troubleshooting tips would be much appreciated.

 

[reptilezs]

worn chain, worn cassette or free wheel. ratchet pawls could be shot.

 

[kirrill]

so, new rear wheel + cogset and a chain to start?

 

[bstyle74]

since it's on the power stroke, i'd guess its the chain, cassette, and chainrings (or any combination of the 3). if it has been sitting for a LONG time, then give everything a good cleaning and lube before you start replacing stuff. the rear hub should be ok... if your rear hub was shot, it'd have problems spinning even going downhill..

 

[KevinB]

so, new rear wheel + cogset and a chain to start?

You should not need a new wheel (unless there are other problems that you're not telling us about).

I think it's likely that you need a new chain, cassette, and chain rings. You might be able to save a bit of money on the chain rings if you only replace the ones that are worn.

 

[kirrill]

Thanks guys. Haven't tried fixing it yet, but probably this week.