Making a short cage work with a 29 cog

[vqdriver]

I can shift to the 29 cog fine but the upper pulley runs along the bottom of the cog and runs noisy. I can manually push rd body down a bit to make it run silent but there's no adjustment screw on the rear of the mount like my shimano RD to back it off, just a metal tab thing. Advise? This campy btw.

[oldpotatoe]

I can shift to the 29 cog fine but the upper pulley runs along the bottom of the cog and runs noisy. I can manually push rd body down a bit to make it run silent but there's no adjustment screw on the rear of the mount like my shimano RD to back it off, just a metal tab thing. Advise? This campy btw.

Look underneath the cage, where the cage attaches to the der body. There's a wormgear/screw end..lefty turn and that tightens a spring in there rotating the top pulley back..like a b limit screw.

[Louis]

Didn't Campy move the B-tension adjustment screw from the dropout attach point to the cage pivot knuckle a few years ago? However, even if the RD can be adjusted, that doesn't mean that you will necessarily have sufficient adjustment range for the upper jockey wheel to move far enough away from the cog.

Edit: Looks like OldP and I posted about the same thing at the same time.

[vqdriver]

Excellent. I'll try It tonite. Thanks

[Dave]

This is one place where the medium and long cage RDs are different. They have more travel available from the B screw mechanism. You can back the screw out all the way and it still may not clear. That's why I warn people that just because a short cage works on some bikes does not mean it will work on all, because the RD hanger length varies among the brands. The wrap capacity is also affected by the chainstay length.

Campy overlooked this when they first came out with 11 speed. For 2010 they changed the B screw mechanism to give it more travel so the short cage RD will work with a 29T cog. They also offer a 12-29 cassette.

[Ralph]

On some bikes....there is more to it than just turning the B screw until you have clearance between the pulley and the big cog. You have to keep enough tension on the chain to keep from throwing it off on front shifts (even on a properly adjusted FD). You may be running the chain a little long in order to wrap up all those teeth. So sometimes it will shift OK in rear, but not work OK overall. You can usually figure all this out easy enough.

I do run a short cage RD on a 9 speed with a 14-28 and a 10 speed 13-29. But the 14-28 on the Cannondale works better with a mid cage....for reasons noted in posts above (short hanger, short chainstays). I have a mid cage I'll probably use next time I change out chains. Another thing I like about a mid cage is the ability to use a IRD 12-32 if I occasionally wished, with my installed 39-52. Where I ride most of the time, I don't need a compact crank, but it would be nice and simple to ocassionally slip on bigger rear cog than 13-29....without making any other changes.