skipping under pressure

[voithofer]

Greetings,

I just bought a used 05 Prophet. I'm having problems with it skipping gears when I put a lot of pressure on the pedals going up steep hills. When it happens it jumps up 2 to 3 gears (to smaller cogs). I'm trying to figure out if I need to replace the cassette and chain or the rear derailleur (XT RD-750). The reason that I think it might be the derailleur is that the chain (Dura Ace) is within spec. (Well within the .75 mark on the park chain tool). The cassette doesn't appear to be worn a lot but I'm no expert in telling that by sight. I have put a new shifter cable on and have adjusted it so that it shifts smoothly. I have also checked for stiff links and haven't found any. The rear derailleur seems to be quite loose when I move it side to side, but again I don't know what is acceptable. Any thoughts on how to better troubleshoot this would be appreciated.

thanks, rick

[Westy]

Sounds like a worn cassette to me. They don't always look worn unless you place it next to a new one.

[Quo Fan]

Could also be a bent derailer hanger. That will cause ghost shifting, too.

[jonKranked]

Sounds like a worn cassette to me. They don't always look worn unless you place it next to a new one.

might also be the chain. brand new chain + used cassette can also = problems.

And like quo fan said, might be a bent hangar too. Have this checked as well before you purchase anything.