Bicycle Mechanics - Rear Derailluer Clicking/Jumping

Well to make long story short, I got my new scratch built roabd bike back from the shop that assembled it awhile ago. Long story as to why I didn't build it up myself. I go to ride it and the rear derailluer is behaving wierdly as I pedal and apply force it almost seems to slip and give a clicking noise, it's hard to describe it's not like it's jumping gears but like tthe cage moves forward and then jumps back a little. It happens in all gears. How do I fix this?

Is everything new? rear derailleur? chain? cogs? rear hub? Does the bike have a replaceable derailleur hanger?

Does barrel adjuster need tweaking?

If the drivetrain components are new, or newly cleaned/adjusted/greased, you might want to check the alignment of your derailleur hanger.

Used rear derailuer, used cassette, and chain is a dura ace that I was told by the LBS was a new bike take off (could it possibly be a 10 speed chain and that is causing the problems). I tried playing with the barrel adjuster but couldn't fix anything, basically I can build a bike from the ground up and get everything adjusted correctly but can't tune derailluers I guess I'm not patient enough so I always have ashop do that. I guess I'll take it to another shop to have it investigated, it really pisses me off that the shop i paid to have do it did it so badly, it's not even usable. Never going back there again for a variety of reasons.

stiff link on chain? rotate the chain slowly in reverse through the the cycle a couple of times and look for a link that keeps its kink as it comes out of the derailleur. symptoms sound exactly like what you describe and it is a snap to fix

Used rear derailuer, used cassette, and chain is a dura ace that I was told by the LBS was a new bike take off (could it possibly be a 10 speed chain and that is causing the problems). I tried playing with the barrel adjuster but couldn't fix anything, basically I can build a bike from the ground up and get everything adjusted correctly but can't tune derailluers I guess I'm not patient enough so I always have ashop do that. I guess I'll take it to another shop to have it investigated, it really pisses me off that the shop i paid to have do it did it so badly, it's not even usable. Never going back there again for a variety of reasons.

If not cable tension, some possibilities are:
- a new chain and used cassette is a bad mix, although it seems unlikely you'd experience jumping in all gears
- chain too long
- bent derailleur hanger
- pins in derailleur badly worn (or just a crappy derailleur)
- damaged freehub pawls

Something is grabbing at the derailler and yanking it. This could be caused by the chain. It could also be caused by an incorrect derailleur alignment; the rear derailleurs pulleys could be making contact with the cogs thus that grabbing effect, if this is the case then you need to put the cage into more of a downward angle so that when the derailleur is in the middle gear the cage should be vertical. This allow the cage to move either forward or backwards when shifting to bigger or smaller gears to take up the chain slack.

The only other possiblity, but remote, is that the cage itself is too short for wide spread or range gears (assuming your not using racing gears) when a long cage would have worked better. I can't see an LBS making that kind of blunder...but? The short cage would allow the cage/pulleys to contact with the gears especially in lower and higher but not in the middle if they adjusted it for the middle.

New bikes undergo 'cable strech', it's normal. Causes something similar to what you're describing. The shop usually has a 30 day period or something where they'll take care of it.

Yikes, I must have gotten another thread confused with this one because I thought this poster said it was built with used parts!?!?!? I got to go to bed!!!!

Chain may be too long too.

Yikes, I must have gotten another thread confused with this one because I thought this poster said it was built with used parts!?!?!? I got to go to bed!!!!

Yeah it was built with parts that I had left over from other bikes I have worked on and upgraded over time. they all seem perfectly good (except for this problem) and don't see why I should by new parts when good used one that I already have are available. Just for reference it is all Ultegra except cassette, standard front (cranks double), I think I will take it into another more competant shop, I'm starting to think the chain is probably to long. Also it's not cable stretch this was the first ride.

Yeah it was built with parts that I had left over from other bikes I have worked on and upgraded over time. they all seem perfectly good (except for this problem) and don't see why I should by new parts when good used one that I already have are available. Just for reference it is all Ultegra except cassette, standard front (cranks double), I think I will take it into another more competant shop, I'm starting to think the chain is probably to long. Also it's not cable stretch this was the first ride.

Before replacing the chain try the derailleur adjustment I mentioned in my last post, if you haven't checked and adjusted that yet, and see if that clears up the problem. The derailleur when adjusted correctly will take up the chain slack IF the chain is the right size.