Jockey Wheels Riding on Cassette
 

I'm new to the Bike Forums, and I have a question that may be obvious to someone a bit more experienced than myself with how rear derailers work.

For some time I've had a problem with the top jockey wheel riding or hitting my highest gear. It sounds and feels like a subtle grinding. What is going on? I have adjusted the set screw that is supposed to push the damn thing away from the cassette, but it is not doing the trick any more. So, short of replacing the set screw, shouldn't there be something else I can adjust?

I just replaced my casette too, for a different reason. But now it seems to bump or hit even worse.

I'm riding with a Shimano 400CX derailer (is that a piece of crap? I don't know) and a new SRAM PG-850 12-26.

My inclination is to replace the derailer. But something tells me that is not right. HELP!

Tighten up the B-tension screw on the rear of the derailleur.

I have tightened the B-tension screw as much as it can go. It seems to be a bit bent, or at an angle anyway, so maybe the thing that it screws into is bent.

It appears that by removing the spacer from behind the casette, and thereby shifting the entire cluster towards the wheel by that small amount, might have done the trick. Its not riding as hard on the normal configurations. Of course, when I go to my granny up front and to the 26t on the rear, it still rides/hits big time.

Any other answers would be sooo sweet.

Have you checked that it's not bent, check the derailler and the hanger to make sure that neither is bent in some way, you might also try removing the derailleur from the hanger, and try to position it towards the back of the bike a little, and see if that helps. I would guess that the hanger is bent by a mm or two, and that is why removing the spacer helped. If it is bent, then take it to your LBS to get it realligned.

Might want to check your chain length. If your B-tension adjustment won't correct it, your chain might be a little long.

If the B screw is not contacting the flat lip on the right dropout then it is indeed bent or the derailleur is improperly installed. The screw pushes against that lip so that when it is screwed in, the derailleur is moved farther away from the cassette. Sometimes when a derailleur is installed, the B screw is not kept clear of the dropout and is sort of "mashed" up against the side of the dropout. You can keep the screw clear by holding the body of the derailleur back while tightening the mounting fastener. Chain tension (length) and spring tension in the derailleur also affect this adjustment.

This is all quite helpful. Thanks for your feedback. I'm going to try to shorten the chain by a few links, and if that doesn't do the trick then I'll bring it in to the LBS to see about some bent frame/derailer problems.

Thanks!