so i've been having an issue with my rear derailleur, where it is making a sort of clicking/ratcheting noise, many times for each pedal stroke. closer inspection reveals it to be that the cog teeth are bumping up against the the pulley teeth. this is something that would normally be taken care of by adjusting the "b" screw. unfortunately, mine is already as tight as it can get.
i had hoped that a new, shorter (less stretched) chain would increase the chain tension and pull the tensioner enough to move the cog and pulley apart. but no go.
is there something else i can do? is a spring wearing out inside the thing or something? and if so, can it be replaced? do i need to get a new derailleur? please say no.
Primarily, I wouldn't worry about it.
Are you sure about the B tension screw? You want to turn it to the right (clockwise) as far as you can.
What size is the largest cog in your cassette?
The chain has nothing to do with it, nor will it.
I suppose I should also ask at what point did this start happening?
i figured it's not going to do any real damage, but it's hella loud, and i hate riding a loud bike, especially since i just prettied it all up.
yeah, i'm pretty sure it's the b screw. i actually examined the derailleur and knew that was what to adjust by looking at it, before i even knew what it was called. it is tightened as much as possible. a longer screw might work up to another 1/8 inch or so, but beyond that, it'll be rotated below the tangent line, if you know what i mean.
the biggest cog is a 28t. it's quieter, but happens in smaller cogs. i don't recall, offhand, exactly how far along it goes, but i can get back to you on that tomorrow.
to address the last two parts simultaneously: i noticed that a shorter chain increased the tension on the tensioner, which "lifted" the pulley off the cog. in the fall, i had a chain issue, and as a quick fix, i removed a link from an old stretched chain. that seemed to fix it. i don't recall exactly at what point i first noticed it, but it came on gradually. quietly, like what is that? then louder, then happening on more than just one cog.
At first guess, sounds like the rear deraileur cable needs to be tighter, and the b screw backed off a bit. but if it was working before, something in the drivetrain must have changed... new cable? new rear cassette? maybe the new chain isn't playing nice with old cogs? did the bad shifting start with the new chain?
shifting has been fine, quizbot. the cable is adjusted just wonderfully. i'm completely certain the b-screw is the issue.
i bought a new cassette last spring. i suppose that could've been a contributing factor, but it didn't start then, and it had the same biggest cog.
the bad shifting started last fall with an old chain. i was hoping the new chain would fix it, being shorter and increasing tension on the tensioner.
and lastly: i fixed it, at least for now. based on a tip i found elsewhere, i flipped the b screw around, which gives it a bit of an extension. no more cassette/pulley rubbing at the moment.
Are you sure the hanger isn't bent?
an internally geared hub would solve all your problems forever.
Take Rickys' advice, install an internally geared hub, perhaps with a disc brake accompaniment. All your problems gone. The Shimano Nexxus series is a shifting dream.
