Question on Campy RD

[SamIAm]

For the first time ever, I'm in need of adjusting the "B" screw on a derailleur. Its never come up before, but on a recent build the clearance on the largest 2 cogs is too tight.

I think the chain is sized properly.

I know there is no B screw, but there is this other screw that supposedly, when turned counterclockwise will increase the clearance.

I have turned that screw every which way and don't see any noticeable difference.

Am I missing something?

[cmg]

there is a screw that is on the bottom underside of the mounting bracket. go to the park tool site http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur for additional info.

[Lewis Moon]

The best thing to do is to put the bike on a stand and turn the screw while turning the cranks. It's not so much that you'll see the difference, it's that you will hear it. It will quiet down as the cage moves away from the cassette. The trick is to move it just far enough away to quiet the noise.

IMHO
YMMV
ATMO
IYDTYPD

[Columbus SLX]

For the first time ever, I'm in need of adjusting the "B" screw on a derailleur. Its never come up before, but on a recent build the clearance on the largest 2 cogs is too tight.

I'm guessing you're not trying to set up a climbing cassette with over 29 teeth on the big cog, right?

What the other guys said about the B-screw, it'll work unless there's something amiss with the unit itself.

[Dave]

If you turn the screw out enough, it will disengage from it's mating part. Turn it out that far, then back in about a turn. That will maximize clearance, if that's what you need.

The clearance is needed in the little ring and largest cog. Shift to that combination when adjusting and spin the crank a few turns after the adjustment, to see the result.