Do I need a SRAM rear derailleur with a SRAM twist grip shifter? My rear shimano derailleur moves two gears with the SRAM shifter. I'm assuming the ratio with the SRAM is 2:1. To complicate things, I found an old SRAM rear derailleur that says 1:1 ratio on the derailleur. Does this mean it will work with Shimano shifters? Will it work with SRAM shifters? I am hoping someone who knows will school me on these ratio questions. Thanks a million in advance. I almost wish I had a graphic to make this more appealing....