RoadJerk

I have a problem upshifting. It will upshift to the the third smallest gear but after that it gets stuck. The funny thing is, I can't tell why. The derailleur has a full range of motion, and I have adjusted it properly. The jockey (lead) gear on the derailler positions the chain over the correct gear, but the chain doesn't want to move off the current gear and onto the next one.

The thing obviously wants to shift, and it makes that rattling noise that sounds like the chain is about to move to the next gear, but it just cant for some reason. The derailleur is pulling all it can to get it over, but the damn thing wont move. The chain is pulled by the derailleur over the right gear, but its like some invisible force is making the chain cling to the lower gears. It just doesn't make any sense.

What's going on?

Ware

I'll have to tell you to wait for some other responses as well, but I think you may just need to increase the tension a bit. If it's shimano (possibly other brands too, but i have no personal exp with others), then there should be a barrel adjuster at the rear of the RD. Turn it a quarter turn at a time (clockwise i believe) until it begins to shift properly. Keep track of the original position, though, in case that isn't the problem and you need to go back to the original setting.

If that works, you should make sure that you haven't overtightened by checking to see if you can downshift all the way back up the cassett.


Or, you could always do yourself a favor, disregard me, and check out parktools.com

RT

...or post this in the Mechanics forum...

AndrewP

Moving to bigger cogs is downshifting not upshifting. If this is a new bike (or new gearshift cables), the cable housing has settled into the stops - this is generally known as "cable stretch". Unscrew the knurled adjuster on the back of the rear derailler 1/4 turn.

Davet

Is this a new install or a new cable? If so, maybe you didn't ensure the shifter was in the relaxed position by operating the small lever a handful of times before you hooked the cable up to the derailleur. Detach the cable from the derailleur, pull some tension on the cable (by the downtube) while operating the small lever until the cable doesn't move anymore. Re-attach the cable to the derailleur and retune the der.

RoadJerk

I actually found out what was happening... I've been working on the bike upside down, and for some reason when I do that the little cable feed thing drops down in front of the gears on the smaller chainrings and actully blocks the chain from moving...

case closed