smokeysurvival

Hello all. Sometime ago I replaced my cassette and chain (same cassette size and chain properly measured to length), on my bicycle and ever since it has had irregular shifting issues, on and off. It went away for a bit after replacing jockey wheels, but I decided to do a chain cleaning a week ago and removed it, and reapplied with chain L, and re-installed the chain and the issue is back. I'm running a 3x9 setup (sram x-7 rear, sram x-gen front), and basically this is the problem. I generally commute in my 2nd chainring in the front, and 5-7 in the rear, or 3rd chainring and 5-6 in the rear and whenever I shift into by 3rd front ring, the rear derailleur cage catches something I suppose and the cage jumps forward and falls back down every few revolutions. Sometimes it gets pulled forward, up to the chainstay, gets stuck, and makes a terrible noise while hampering pedaling, until I coast, then it drops back into the proper position. It will do this unless if I'm in the 2nd chainring, and shift all the way up to 9 in the back, and back to 5, then into my 3rd chainring, then it doesnt do this jamming anymore. It also never does this when I shift the chain while not riding the bike (upside down or in a stand), only when I'm riding it. Can anyone help and tell me that is wrong? Thanks

demoncyclist

Did you adjust your derailleur when you changed cassettes? Manufacturing variances would dictate this as a necessary step- reset H and L screws as well as cable tension for proper shift points.

smokeysurvival

yes I have adjusted tension and the high and low limit screws. The shifting goes to each ring quietly and swiftly in every combination while off the bike and on, but I still get the derailleur slapping. I've tried the whole process again today twice with no relief. immidiately after adjustment it doesn't happen but it soon starts malfunctioning after a few on bike shifts, and now it's developed a clacking while I pedal. I've notice that the bottom run of the chain bounces while pedaling, but not during coasting. I cant tell if it's normal or if the derailleur is some how causing it, but could this mean my chain is possibly too long or too short?

J.C. Koto

A failing freehub mechanism can cause similar symptoms, so you should rule that out: remove the rear wheel and with the cassette facing you, slowly and gently turn the cassette counter-clockwise, listening closely for the clicks as the pawls fall into position. The clicks should feel and sound smooth and even with no intermittent gaps or double-clicking sounds. While doing this, occasionally give a sharp turn clockwise to engage the pawls as if you were pedaling, then resume gently turning counter-clockwise.

If at any point when you're turning the cassette counter-clockwise you feel a catch or stutter (you'll know it if it happens because it suddenly feels or sounds much different) the freehub needs to be replaced.

smokeysurvival

Nope, the freehub is fine, I even removed the cassette. Did a cleaning through a chain jig and removed the derailleur to inspect the hanger (remembered I never greased it), and get all the road crud out and noticed the top jockey wheel had quite a bit of play in it, so maybe that was the issue. Removed, added two shims and reinstall with threadlock on the screw, too late at night for a test ride though.

ThermionicScott 

The jockey wheel is supposed to have play in it.

smokeysurvival

I know there should be some play, but compared to the bottom jockey this one had about twice as much. Just a thought.

ThermionicScott 

Yep, the lower one isn't supposed to have much.

https://sheldonbrown.com/gloss_i-k.html#jockeypulley

smokeysurvival

Well I did a 2.5 mile test (groceries), and that seems to have eliminated the issue thankfully. But thanks to everyone's for their input, it's all greatly appreciated.