The XTR M9100 I-Spec shifter gets updated to a new system (dubbed EV), which is not backwards-compatible with previous I-Spec. The new system offers 60-degrees of rotation adjustment, and 14mm side-to-side adjustment, both improvements over the previous I-Spec.

The nifty addition of a little rubber grip pad onboth shift leverswill help keep your thumbs from slipping off the paddles, and fordownshifts, Shimanos 2-Way Release feature allows you to use either your thumb or index finger. You can also downshift two gears at a time by pushing your thumb past the first click into the second click. It does require a bit more pressure on this shifter compared to previous Shimano shifters, so as to avoid accidentally double downshifts.