Dyna-Sys combines features like quick-shifting Close Step front gear ratios (think: bigger granny, smaller big ring), a wide-range 11- to 36-tooth 10-speed cassette & re-engineered shifters & derailleurs that are less susceptible to trail chatter or contamination. Together, Shimano Systems Engineering unlocks performance & versatility never before seen in a triple, & its all tied together with the industrys first mountain-bike-specific 10-speed chain. Riders who would otherwise have to pull the ripcord & battle technical climbs from the trenches of their granny gear range can now push further up the trail in their middle ring thanks to the increased range of a 36-tooth low-end rear gear. The granny gear is still there, youll just need it less, & the 42-tooth big ring is more useable & easier to get into than ever before, so youll use it more. Simply put, XTR Trail is the most efficient mountain bike drivetrain singletrack has ever seen