Cassette question

[TimS]

Dura Ace 9 Speed:

I have always ridden a 12/25 cassette. For some reason an old 11/21 one was on a set of wheels that I gave a try. Skipped under torque. Big ring, two largest cogs. Installed new 12/25 - not a problem.

Question: Is the 11/21 cassette toast or is there a reason why a different cassette configuration would cause the skip other than being worn?

Thanks,

Tim

[jamesdak]

Chain probably too loose running the 11/21 would be my first guess.

[bikinchris]

Your 11-21 is probably worn out. Unless your chain is going completely slack. If you know someone with a Rohloff cassette checker who can tell you for sure, they can tell you.

[Dave]

The most worn sprockets on a cassette will usually only skip with a new or nearly new chain. A chain that's had 3-500 miles of use usually won't skip on those worn sprockets.

Chain length should not be the problem. Reducing the smallest sprocket by one tooth is the same as 1/4 inch more chain. If the chain hangs loose, it would only be in the little/little, that shouldn't be used it still wouldn't cause chain skip.

I have a setup that exceeds the RD's wrap capacity, so the lower section of chain is loose in the small ring and two smallest sprockets. It works fine. The top section of chain is what drives the bike.

[Wattvagen]

not all rear hubs have the same exact dimensions. it's certainly possible that the different wheel you tried put the RD slightly out of optimal alignment and caused a skip.