Bicycle Tutor

On my older Canondale Mt.bike, I replaced the SRAM 8 sp.casette with another SRAM 8 sp., and I replaced the SRAM grip shifters with a cheaper pair of 5.0 8 sp. Grip shifters, and the rear derailleur with a Shimano Deore M591. After reading, I realize my shifting issue is the compatibility problem between the SRAM shifters and the Shimano rear derailleur, different ratios. So, I'm inclined to replace the shifters, but I can't seem to find 8 sp. SRAM shifters other than the cheap ones with 1:1 ratios which is incompatible. What might work, either grip or trigger, and does it matter if you put a 9 or 10 speed shifter with an 8 speed casette? I would think the numbers would be off, but it would work. Thanks in advance.

The number of speeds on the shifter must match the number of sprockets on the cassette, so you have to use 8sp shifters with an 8sp cassette etc.. In addition, as you've discovered, some Shimano shifters are incompatible with some SRAM mechs and vice versa.

So, you need an Shimano, or Shimano compatible 8 speed shifter to go with your Shimano Deore M591 derailleur.

Here are some that should work:

http://www.tredz.co.uk/.Sram-MRX-Twist-Shifters-Shimano-Compatible-_34047.htm

http://www.chainreactioncycles.com/Models.aspx?ModelID=38697