Electronic shifting reaches the mountain bike world: Shimano XTR Di2 M9050


It was only a matter of time until Shimano would introduce the electronic shifting option for its mountainbiking groupsets, and that moment has come now, XTR having another sibling, the XTR Di2 M9050.

The options in terms of mountain bike specifications already abounded, with choices like single, double or triple cranksets, but the new options that made their way through together with the new XTR expand even more this array of possibilities and useful features. For instance, one would be the E-Tube platform, which connects the shifters with the electronic suspension fork Fox ICD, and which has a display that shows the fork’s set-up aside the usual gear and battery level that the Di2 system reveals.


Is electronic shifting that good? For what it’s worth, shifting now requires minimum efort (not that mechanical shifting requires a lot of brawn), with the mention that the two derailleurs cleverly auto-align themselves so as not to come into unnecessary contact with the chain. Another bonus, rather significant, sits in the fact that, over time, there is no alteration of the initial adjustments of the two derailleurs. Of course, the problem of the broken cable is still the same, such an issue representing the nemesis of any kind of drivetrain, electronic or not.

Shimano considers Firebolt to be the biggest achievement of the XTR Di2 M9050 groupset for the fact that you can actuate both derailleurs using the same shifter. Firebolt works hand in hand with the Synchro Shift option, a truly innovative system that has embeded in its memory the most efficient pattern of gear usage. The front derailleur reads the position of the rear derailleur and automatically operates the front shift to position the gears in the most efficient gear and best chain line so the rider never has to worry about front shifting and correction shifts again. Basicly, it follows the torque value and tries to keep it constant regardless of the gear you are using. Synchro Shift is best explained in the video below.

Shimano also developed the E-Tube platform, which not only allows choosing the desired settings of the derailleurs, but also programming them. Thus, you can actuate the front derailleur using the right shifter, and the rear derailleur using the left one, while multiple shifting is also something that the XTR Di2 M9050 has mastered, enabling you to choose whether you shift over two cogs, or over the entire cassette. An advantage of the electronic system is the fact that the same push of the button sends the derailleur flying over how many sprockets you want, be it only one or the entire cassette, an option that was conditioned in the case of mechanical groupsets by the length of your fingers.


Some adaptations of the actual derailleurs were required for the new set, the big news being that both of them are significantly stronger according to the manufacturer, as the direct result of the fact that shifting under load is much more frequent in their case. Kudos for the auto-trimming option as well! It almost seems that these two components are aware one of each other and have a mind of their own.


The jewel and brain of the Shimano XTR Di2 M9050, however, is the digital display which shows information about the battery level, gear you are using, whether Synchro mode is enabled or not, or what mode is the fork currently using. But that’s not all. You can change the shifting mode while riding, and the display is also responsible for recharging the battery (the same one as for the road Di2 sets, SM-BTR1 and SM-BTR2), and connecting to the E-Tube platform.

With all these new features, maybe some unwanted weight gain would have been expected, but in fact, the XTR Di2 M9050 is only 47 grams heavier than its mechanical counterpart:

  • Front derailleur (FD-M9070 D-type) : 115 grams
  • Rear derailleur (RD-M9050-GS) : 289 grams
  • System display (SC-M9050) : 30 grams
  • Shift switch (SW-M9050) : 64 grams

What the press release failed to mention are the prices, but we’re bound to find them out by this autumn when the groupset will hit the market. Neither did the release say anything extra about battery life, so, relying on the fact that the batteries are the same as for the Dura-Ace and Ultegra groupsets, they have an autonomy of more or less 1.000 kilometers, depending on weather conditions and degree of usage.