eandmwilson

Enough acronyms yet?

After changing my rear tire, all of a sudden my RD is all goofed up (DA 7800). The bike was upside down when I changed the rear wheel, and I was very careful not to bang it during the remove and replace. By goofed up I mean it makes a racket in tenth gear regardless of where I set the adjustment screw (and on big or small ring). And by racket I mean you can hear every tooth of either chainring engage. I've checked the front end of the drive train and the chain is not rubbing on anything. Additionally, from the rear, the guide and tension pulleys look to be slanted inward a bit towards the wheel. I'm not saying this is new, I just never noticed it before. The inward slant makes it hard to get into first gear without the spokes banging off the outside of the pulleys, which is not my happy place.

I've played with the B screw (which is supposed to move the pulleys in or out from the cassette), and haven't seen any appreciable change in position. All parts are lubeD, and the bike has been indoors on a trainer for the last few months, working just fine.

Any ideas? At this point I'm tempted to start from zero, but I'm not sure things aren't really goofed up.

recneps

Um i would jsut check the h and l screws and make sure theyre perfectly lined up, thing is a good mechanic dosnt look to see if theyre lined up they can hear which way its off so its kind of hard for normal people like me to be good at sdjusting RDs, but keep trying youll get it right.

as far as the b screw, chain wrap usually dosnt cause many problems with not shifting perfectly in my experiance.

merlinextraligh

First, Make sure the wheel is fully seated in the dropouts.

Second it sounds like you were changing the limit screws, which probably wasn't the problem. Make sure they're set correctly to keep the derailleur off the spokes, and the chain off the frame on the other side.

Third, adjust the barrel adjuster in small increments until the sound goes away.

Fourth, if that doesn't work, check the derailleur hanger alignment, but it sounds unlikely that you bent it.

My bet is the wheel just isn't seated in the dropouts precisely the way it was before.

fly:yes/land:no

+1

JayC

+2

I never seem to get the wheels seated right when the bike is in the stand. I always take the bike off the stand and put it on the ground and seat the rear wheel then put it back in the stand.

slowandsteady

Yup, your wheel is crooked. If your spokes are hitting the RD either the RD or hanger is bent(doubtful) or your wheel isn't straight.

richphoto

Its pretty easy to bend a rear D hanger, My brand new Cervelo hanger was slightly bent, I am guessing in shipping somehow, There was more noise on the rear than should be so I adjusted and adjusted and could not figure it out. So I removed the hanger to find it was in fact bent. Its sometimes hard to tell unless you take it off and lay it on a flat surface.

slowandsteady

Not really. I am just thinking about the hundreds of times I slammed my bike down onto the pavement as a kid and never had anything bend. Plus the OP said he was very careful and didn't have any issues until he remounted his wheel.

eandmwilson

Yeah, I'm pretty sure the hanger is OK. There simply was no possible impact on that part of the bike.

I'll try tweaking it some more. Chain stretch is also a possibility, but unlikely--I think the issue is side to side vs front to back.

eandmwilson

Found the problem--there was some sort of U-clip that apparently is part of the QR skewer on the drive that got popped up into the cassette area. The .05 mm shim, or whatever it is, was enough to throw off the whole shifting scheme to the crapper. I slipped the clip back onto the skewer, and it all worked out.

iNewton

Isn't it awesome to listen to a perfectly aligned derailleur after figuring out the noise problem.

richphoto

Oh yes!