Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 6 Post(s)
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As the others said, it could be a barrel/trim adjustment, or could be more complicated, but you might as well start with the simplest and either solve the problem or eliminate it before looking farther.
The last section of housing ends at an adjuster on the RD. If you turn it outward, it lengthens the housing, effectively shortening the gear wire, and moves the RD inboard. Turn it in and the opposite happens.
Leave your bike on the trainer, but lower the resistance unit so the wheel spins freely. Put your bike in any gear and eyeball the chain and cassette from the back. See if it's feeding perfectly centered onto the sprocket. If not turn the adjuster until it's centered then run through the gears. Ideally it should be smooth and quiet in each gear and shift equally well in either direction. If it shifts inward better than outward turn the barrel in a bit, or out if it shifts out better than in. Since you're new at this feel free to experiment, trial and error with 1/4 turn adjustments until you dial it in.
When you're finished, double check that the inner limit is OK by pulling on the bare wire and trying to shift beyond the low gear cog. If the chain goes over the top, tighten the low gear "L" limit screw by 1/4 turns until you cannot make it overshift.
If you can't solve the problem easily this way, it could be a bent hanger, especially if you wrecked your knee and foot crashing this bike.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance