My Trek Mtn bike came originally with SRAM 400 (7 speed) shifters. I recently purchased a set of SRAM 3.0 (7 speed) shifters. I can not get the new rear derailleur to work properly. I would have thought the new shifters would be compatible. I can shift from the lowest to highest gear, but I skip one gear in between. When I'm on the largest cog, the shifter is on #6 rather than top gear #7. I measured the amount play on both shifters and the new 3.0 shifters have more play than the older 400 shifters. Any help would be appreciated

SRAM has two lines of shifters with different actuation ratios. One is Simano compatible, the other require a SRAM derailer with a matching actuation ratio to index properly.

400s are Shimano compatible, which means 2:1 cable pull. 3.0s are SRAM compatible, which means 1:1 cable pull. You must have a matching shifter and RD.

Yellowdog: My understanding is that SRAM shifters with names (Attack, TRX) are compatible with Shimano 2:1 pull; the ones with numbers (X3, X7) are compatible with SRAM 1:1 pull derailleurs.

I acquired this bike as parts, and all I had was a SRAM 3.0 shifter set. I found out it - like yourself - that it wouldn't work right, sometimes skipping a gear for each click.


I modified the 7-speed shifter by dremeling extra detents into the inside ring. Being I needed a 2:1 ratio, adding a detent between each of the stock detents gave me the clicks I needed. Thing worked like a champ. Alot of work, but functional.