Campy 10 speed rear compatability
 

Simple question for some of you experienced mechanics. I currently have a campy chorus derailleur on a bike with a 12-25 cassette. Can I use the same derailleur if I go to a 12-28 or 12-29 cassette? i believe it is a short cage. I'll post a picture. Too many tough hills! Thanks in advance. Sorry something has changed since I last posted. I can not post the picture.

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campagnolo chorus rear derailleur capacity

I am using a Chorus short cage derailleur with a 12 29 cassette. Works just fine

It was always my understanding it would work. I thought it was a 13-29 that was available. I haven't looked in a long time.

Officially no, although it works for many people because the specifications are based on tolerance for different derailleur hanger configurations and no slack in small ring x smallest cogs.

Officially, short is for doubles and all cogs except 13-29 (and by inference the newer 12-30). Medium is for doubles with all cogs, and triples all except 13-29. Long is for triples with larger cassettes.

Campy 10 speed rear compatability
 

Thanks for the information. My friend is on the lookout for a new cassette.

it positively works - i run sc derailleur on 53/39 with 10sp 12-30cassette. just don't use (not the end of the world if it happens) combo 53/29. according to the official campy spec the capacity of the rd is 32, min cog 11. so, if you use compact 50/34 use sc der with 12-28, for standard crankset 53/39 12-29 is fine. 11t pulleys might extend the range even more.
hope this helps.