Mixing SRAM shifters and Shimano derailleur

[JonB]

SRAM do an ATTACK series of trigger shifters and grip shifters that work on the same ratio as Shimano (and are therefore compatible). That's probably what you've got, and they tend to be found on entry level mtbs, hybrids, etc. where high performance isn't as important. I'm not saying they're bad, they're actually very good for the money I think but they lack the durability of more expensive models (which is important in the world of serious MTBing).