Been a long while since I played with my Bianchi Varsity hybrid, but I'm pretty sure the Deore Mountain LX shifters used to work as index shifters. For some unexplicable reason, they now don't. Both front & rear thumbshifters are working only in friction mode. Even in friction mode, the rear thumbshifter won't hold its position, so when moved to the largest (rear) sprocket, the chain just falls by itself to the lower sprockets, as the tension releases. I have tried moving the little friction/index mode switch on the rear shifter into all different positions. I have tried playing with the cable tension screw next to the shifters. I have tried taking the thumbshifter apart, and also tightening the screw that holds the assembly together. I have tried adjusting the tension on the rear derailleur, and making sure it isn't slack when in the smallest rear sprocket (high gear). Still can't get either thumbshifter into a working index mode....
I'm sure I'm overlooking something... but what?!
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I'm sure I'm overlooking something... but what?!

