Thumbshifters won't work in index mode?



Madz

New Member
Aug 10, 2009
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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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front-1.jpg
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artemidorus

New Member
Mar 10, 2004
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The Mountain LX front shifter was never indexed.

The indexing unit inside the rear shifter engages 4 little pins into holes in the shifter mounting bracket. These are vulnerable to damage - if they shear, then the unit won't hold cable tension in either mode because the lever and the internal indexing unit are then not fixed in relation to the mounting bracket. Check and see if they are intact.
 

Madz

New Member
Aug 10, 2009
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artemidorus said:
The Mountain LX front shifter was never indexed.

The indexing unit inside the rear shifter engages 4 little pins into holes in the shifter mounting bracket. These are vulnerable to damage - if they shear, then the unit won't hold cable tension in either mode because the lever and the internal indexing unit are then not fixed in relation to the mounting bracket. Check and see if they are intact.

Thanks, that was exactly the problem I had observed yesterday. All 4 pins were sheared (one pin on the front shifter was also sheared). I fixed it by gluing the shifter to the mount with hot glue.
 

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