Bicycles Asked by moxen on September 30, 2020
I’ve got a Shimano Sora on a 8-gear cassette, and have odd behavior and skipping, shifting under stress.
This started with a trip to the mechanic for a tune up which replaced the chain. I had some skips so I replaced the cassette. Still more skipping, a second trip to the mechanic didn’t do much good.
I tried adjusting it myself and found some odd behavior:
Any ideas on what’s going wrong here? It seems like tension pulling the chain out is not sufficient, but I don’t see any adjustment for that.
Am I barking up the wrong tree?
A tune-up fundamental SHOULD be the proper alignment of the rear derailleur hanger. If the shop doesn't use a Park Tool DAG-1 [derailleur hanger alignment gauge], or some other manufacturer's, to inspect, verify, and correct the relation of the hanger to 3 different points on rim of rear wheel at 180 and 45 degrees apart it is throwing parts at a bike. As the hanger should hold the rear derailleur in direct line with each cassette chain ring, any deviation -- inward or away from the cassette -- induces erratic shifting and skipping that mimics cassette and chain wear. (Misalignment is difficult to "see" without this tool but may be suspected if the bike has been bumped in a rack, dropped, or fallen, on the drive side.) The tool at $65 to $75 will be used for diagnosis by a careful shop but is unlikely to be worthwhile for an occasional home wrench.
Correct answer by kate on September 30, 2020
I've experienced similar setup difficulties with my rear derailleurs and my advice is to check your cable tension. There a few ways to do this (not all may apply):
Some other spots to check:
Other than this, you might just have to take it in and let the shop do all the work/adjustment.
Answered by Aaron on September 30, 2020
It could be a number of things.
The most likely it sounds as if your cable is sticking/jamming. Try replacing your cable and cable housing. This shouldnt cost much for DIY (read up on how to do it, you dont want to crush the housing when cutting), but would cost more from a mechanic. I would firstly check that your deraileur isnt out of alignment and/or loose or bent first. Another thing you can do is check that you have the right chain for your cassette and that the chain isnt worn (a cheap tool will check this for you).
If your mechanic has not solved this, I suggest trying a different one.
Answered by Mark W on September 30, 2020
At this point the rear derailleur and shifter should be able to shift up and down your cogset. If you're still having issues, you might want to check the shifters themselves.
Some of the older 8 speed levers used to have a problem with releasing. The grease in the mechanism would dry out and cause the release mechanism to function poorly. You would mostly see this when releasing from your biggest cog. You can spray some lube into the shifter body while working the two shifter levers
Answered by Rich Wagenknecht on September 30, 2020
I had the same problem and I solved it by replacing the rear derailleur. You could see it wobble sideways if you moved it by hand. As you already replaced the chain and casette, there seems to be no other option (shifters don't break that often, and they work when changing speeds up).
Answered by Marius on September 30, 2020
The Sora is poorly designed. The hinge should clear when it derails out to the small cog, but when you have the B-screw all the way out and that hinge is pulled in tight, it hits itself (the part of the derailleur that is fixed to the hanger). It is simply having difficulty clearing to the outside.
so... the tradeoff...
tighten the b-screw... Shifting down (or to the bigger cogs) will lag a bit. If you are using rapidfire shifters, you simply just hold the thumb down until it pushes the chain to the larger cog.
Answered by Ben on September 30, 2020
I fixed similar problem with new shifter.
Answered by Jakob on September 30, 2020
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