Electronics are all around us. When was the last time you rolled up a window in a car? Turned a dial to tune in a radio station? Wound up an alarm clock? Been awhile, right? Well, we’ve been pulling cables to change gears on mountain bikes for decades. Our road and cyclocross brethren have been using tiny motors and electronic impulses to shift gears for half a decade now on Dura Ace and Ultegra Di2 drivetrains, and in a not unexpected move, Shimano is porting that technology over to mountain bikes in the form of the new M9050 XTR Di2 group.
The big news is the Firebolt shifters. Since these are just buttons that don’t need to pull or release cable, the feel, shape, and motion has been finely tuned to be as positive and ergonomic as possible. The shifter uses two buttons on each side. Those buttons can be programed to work any way a rider wishes. Left hand for rear derailleur? No problem. Top buttons for front shifting, bottom for rear? Yes, that is possible with a few keystrokes. Also, holding down the buttons can perform a full shift range, or a few shifts. It is up to you.
The most interesting part of these shifters is the possibility of using a single shifter to control a both front and rear shifting. This is called Synchro Shift, and this video does a good job explaining it.
You can see how the gear selection process works in this video from Shimano. It’s not the easiest to follow, but what you can see is the front derailleur moves on its own to select the proper gear ratio for the next step. Also note how the chainring/cog combinations are not always the same shifting up as when shifting down.
A small head unit (SC-M9050) display a lot of info in a small screen, keeping bar clutter to a minimum. The battery can be charged via a port on this unit, great for internal batteries. And it can be also plugged in to program the shifter and other functions.
The whole system is tied together with Shimano’s E-tube wiring system, to create a custom wiring option for each bike. The SM-BTC1 mounts the battery to a set of bottle cage bosses, and has six ports to connect shifters, derailleurs and Fox’s electronic suspension gadgets, all to the same battery.
The derailleurs are pretty tame looking, in fact I almost published a photo of the Di2 derailleur with the M9000 stuff, it looks that normal. The rear derailleur (RD-M9050) has both GS and SGS cage options for single, double and triple cranks. The e-derailleur retains the clutch and low profile from the cable derailleur, for great chain retention and keeping that expensive mech out of harms way.
The front derailleur claims 25 percent more “powerful” shifting than the M9000 front derailleur, whatever that means. The onboard computer automatically trims the derailleur cage, for rub free shifting.
The entire system is well sealed to the elements, as has been proven on the cyclocross race circuit with the road Di2 drivetrains, so there should be little worry about getting things wet and dirty. M9050 will be ready for sale in late in 2014. And while we don’t have pricing, expect a 40 percent premium over the mechanical group (which is still waiting on pricing as well). In other words, not cheap, but you already guessed that.