Campy rear derailleur issue

[67-59]

Anyone know what might make a Campy Record 10-speed rear derailleur suddenly go only part of the way back when trying to shift to a higher gear?

Everything was working fine about 30 miles into today's ride...was in about the 4th or 5th smallest gear and tried to shift into a higher gear, but RD wouldn't move. At first I thought maybe the shifter had died, but I have confirmed that the cable is slackening when I'm trying to shift up, so it is the RD that isn't responding. I can shift all the way down to the smallest gear and back up to the 4th or 5th, but then the RD won't go any further. I thought maybe it was just sticking, but I've cleaned and lubed it, and the problem persists.

I'll be blunt and say I'm a lousy wrench, but I'd like any ideas about possible simple fixes before I take it to the local shop. Thoughts?

[130R]

i would watch this video and have at it!

http://www.youtube.com/watch?v=1KHpyuwIvxE

if that doesn't fix your issue, the problem is in your shifters

gl!

[Ralph]

Sounds like a cable issue to me. But would have to put on my stand to really see what's going on.

[AngryScientist]

sounds like you have something binding, though this would be hard to diagnose without it being in the stand.

i would start by removing the rear wheel and confirm (or not) that the rd can move its full travel using the shifters to pull cable without the cassette in. failing that, remove the cable from the rd and see if you can move the rd over its full travel manually. if you can, the problem is likely your shifters or a cable issue.

let us know how you turn out...

[Dave]

Something may actually be broken in the paralleogram. If not, just try flushing with WD-40 - I do it regularly, just to flush away grit.

[67-59]

Thanks all for the feedback.

I checked the RD itself and it was fine, and the shifter seemed to be working. Then as I was looking closely at the shifter, I noticed the cable fraying and starting to unravel. New cables it shall be....