Top gear problem

bikeit65

My winter bike has shimano gears on it all work great apart from when i put it into the big chainring at the front and the smallest cassette at the rear, it is slow to shift into the smallest cassette sometimes it does not shift right away and then when you are pedaling it shifts, what could be the problem?

John.T

First make sure the cable is slack on the small sprocket. Then adjust the top limit screw so the chain runs freely and shifts cleanly. Also check the mech hanger is not bent.

bikeit65

Cheers John T, if the mech was bent would it not affect all the gears?

John.T

A bent mech hanger can put the top jockey wheel in a different line on each ring. Often worst in top gear. Check the other things first unless you think it is bent. Also worth checking the cable.

dj58

Have you checked that the top guide pulley wheel is directly inline under the top gear sprocket (limit screw not adjusted correctly)? If it is then as John T suggests, check the cable tension fine adjustment and the condition of the inner/outer cable.

If the replaceable dropout is bent this will also cause problems with alignment. I replaced one on my nephew's MTB recently for the same reason, new part c/w new RD solved the indexing problem.