jmh1313

I changed my bottom bracket yesterday, reinstalled the crank, and made sure everything was shifting smoothly in the front. No issues there.

However, now my rear derailleur is jumping as many as 5 cogs at once going from big to small. It's like the cable loses all of its tension with a single click.

Here's the setup: Campagnolo Veloce 10-speed shifters shimergo-ed to a 9-speed Deore XT in the back with the hubbub cable routing. It's worked perfectly for a year, so I know it's not an issue of compatibility.

Things I have tried:

1) Reinstalled the BB and crank, since that's all I did before the problem started.
2) Made sure the rear derailleur wasn't bent.
3) Removed and cleaned the entire drivetrain. Everything is in good shape and relatively new.
4) Replaced the derailleur cable.
5) Adjusted the front derailleur and made sure the chain isn't slipping there.
6) Checked the chain for any kinks or stuck links.

I'm stuck. Any ideas what to do next?

Homebrew01

Sounds like the shifter ratchet is slipping, not holding the cable, so the derailleur spring pulls the chain down to the small cog.

jmh1313

I do believe you're right. The shifter lever is sticking after a couple clicks. I'll lube it and see if that does the trick, but my knowledge of the guts of a shifter is pretty limited, so replacement might be the next step.

alcjphil

Veloce shifters can be rebuilt, one of the strong points of Campagnolo components.

jmh1313

I completely took apart the shifter and lubed everything according to one of those wonderful Campy videos. I don't see any signs of wear, and the springs seem to be springing as they're supposed to.

But I'm still running into the same problem. When I shift up, the shifter completely releases after a few clicks, even when I'm pulling gently on the cable by hand. Any idea what I might be overlooking?