Deore XT is a mountain and touring bike groupset first introduced by Shimano in 1983. It was Shimano's first mountain bike groupset, based on their existing Deore touring groupset, and it consisted of a triple-chainring crankset, front and rear derailleurs, handlebar-mounted "finger" shifters, cantilever brakes, and large-flange hubs. Since then, it has become their "second-tier" offering, the list of components has expanded to include hydraulic disc brakes, a complete wheelset, a chain, and clipless pedals, and it is offered in silver or black finish.
Model history
The groupset is designated by model numbers M7xx; beginning with M700, and currently running to M780. Touring groupsets are designated by model numbers T7xx
References
Shimano Deore XT Wikipedia(Text) CC BY-SA