The rumors are true—XTR will now come in an electronic Di2 version similar to what Shimano has on its high-end road groups.
Shimano released details of a new electronic XTR component group today, officially confirming rumors that have been swirling for months. Just weeks after announcing their mechanical M9000 high-end cross country group’s migration to 11-speed shifting, the Japanese juggernaut has introduced a Di2 digital platform for mountain bikes based on the same architecture it developed for road groups over the past five seasons.
XTR M9050 Di2, as it’s officially called, consists of digital shift levers, front and rear derailleurs, computer displays and batteries that integrate with elements of the aforementioned M9000 11-speed mechanical group. As with the road groups, electricity and data are transmitted via Shimano’s E-tube electronic wiring system. The system can also be configured to control and power FOX’s iCD electronic forks and shocks.
Mini primer: Single, multi-shift and Shimano Synchronized Shift explained
Without the linear constraints of mechanical systems, Di2 allows riders to configure shifting for manual gear changes in either single- or multi-shift modes, as well as for two custom pre-mapped shift sequences via the Shimano Synchronized Shift programming mode.
The manual single- and multi-shift modes are fairly straight forward. Albeit faster, single-shift emulates traditional mechanical shifting, changing gears one at a time with the press of a button. In multi-shift, holding down the button jumps the chain up or down several gears at a time. Shimano says multi-shift can “dump” a whole cassette’s worth of gears faster than could be done with mechanical systems.
Shimano Synchronized Shifting—Synchro for short—allows users to program custom gear sequences based on personal preferences. For instance, most people try to avoid cross-chaining and avoid using the rear cassette’s largest few cogs when they’re in the big chainring. With Synchro, mapping can be set to automatically shift into a more-sensible next gear that doesn’t cross-chain—say downshifting the front ring while upshift the rear derailleur to the next lowest gear ratio—as the sequential step when they get to that cross-chain gear.
Video: This video helps visualize Synchro Shift and its associated gear ratios for 2x and 3x setups.
With the Synchro’s two programs, you can set up condition-specific gearing maps—say Synchro #1 for a course with a lot of climbing, and Synchro #2 for a more flat terrain profile. Toggling between the two Synchro programs and manual setting requires a few button presses and can be done on the fly.
The system actually emits an audible alarm to foretell impending front shifts which riders can preempt by toggling to manual mode.
Using Synchronized Shift only requires one shifter, leaving the other available to control compatible FOX iCD suspension products.
The aforementioned gear controls—dubbed XTR Di2 FIREBOLT shifters—feature ergonomically developed short-stroke switches that mimic the tactility of their mechanical counterparts, but feature lighter action. Because they don’t require mechanical leverage, the radial shifter pods are much smaller than mechanicals and the shifters take up less handlebar real estate. Shimano designed the shifter units to be actuated with either a push-push or push-pull motion.
Complementing the controls is a small head unit plainly called the SC-M9050 Display Unit, which allows monitoring of Di2 data like gear selection, battery level and shift mode. It can also display suspension data for the FOX iCD system, acts as a junction for E-tube wiring, and hosts the system’s power input port for charging.
The XTR Di2 shifters can run gear selection in a number of modes as well as control suspension settings. A head unit display helps you keep tabs with what’s going on.