9070 Rear Derailleur Irregular Shifting
Moderator: robbosmans
My 9070 derailleur started acting up a week ago, and I thought it may have been the pulleys as they were worn and had a substantial amount of play, but I replaced them and the issue seems to continue to get worse. The shifting is irregular and almost acts as if I have crossed cables inside the frame on a mechanical bike. I also sometimes derail the chain from the lower jockey wheel. Is my derailleur dead?
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Bike/derailleur (its on its third bike) has never been dropped or crashed. Chain and cassette have less than a thousand miles on them also. I will check the derailleur hanger next time I can get to a shop but its visually straight.
Derailing the chain from the lower jockey wheel is strange. Make sure you didn’t get the two jockey wheels swapped. They are different. The top one will have some designed side to side play. The bottom one should be rigid laterally.
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On some frames if you don't tighten the skewer to the same tension that was used when gears were indexed it could go out of indexing. Check that your rear wheel is in the right place and tensioned properly. Then check again.
Derailleur hangers tend to need adjustment from time to time. Same as with indexing. Index the derailleur.
Check that the cassette/freehub doesn't move side to side. Maybe one is loose. You check this by trying to move the cassette sideways. There shouldn't be a big noticeable play. Do the same with the smallest cog. Some people forget to tighten the cassette and it loosens over time.
Check that your freehub is coasting smoothly, and do the same with the pulley wheels. If something is sticky it could explain dropping the chain (as well as hanger misalignment).
Did you swap wheels lately?
Also check that you don't have a slack chain in small/small gear combo. Sometimes people size their chains with the b-screw half in and after adjusting it the chain goes slack in small/small.
Derailleur hangers tend to need adjustment from time to time. Same as with indexing. Index the derailleur.
Check that the cassette/freehub doesn't move side to side. Maybe one is loose. You check this by trying to move the cassette sideways. There shouldn't be a big noticeable play. Do the same with the smallest cog. Some people forget to tighten the cassette and it loosens over time.
Check that your freehub is coasting smoothly, and do the same with the pulley wheels. If something is sticky it could explain dropping the chain (as well as hanger misalignment).
Did you swap wheels lately?
Also check that you don't have a slack chain in small/small gear combo. Sometimes people size their chains with the b-screw half in and after adjusting it the chain goes slack in small/small.
