Shimano XTR Di2 - Electronic shifting comes to mountain bikes

Motor controlled shifting with clever sequential mode and interesting integration

Shimano today announced details of a new Di2 electronic version of its top-tier XTR mountain bike groupset.

Rumours, as well as leaked images of the group, have been floating around the net for some time, but now everything is official we can give you the full run-down.

XTR Di2 in a nutshell

XTR M9050 marks the first migration of electronic shifting technology into the world of mountain bikes. The system will use one battery and remain wired, using already proven parts from Shimano’s Ultegra and Dura-Ace road Di2 groups.

So what are the advantages? Shimano claims that XTR Di2 will offer faster and more accurate shifting. Also, with no cables to stretch, it’s said to offer shifting consistency that a mechanical transmission cannot match. Whether that's true remains to be seen, but one part of XTR Di2 that we really should be taking notice of is Syncro Shift – for those who are running double or triple set-ups it could be a game changer.

Syncro Shift allows the rider to control both front and rear derailleurs with one shifter. Simply shift up or down and the transmission will follow a pre-programmed (and customisable) shifting map, moving both derailleurs when necessary to find the next ratio while maintaining a good chain line. So, that’s less clutter at the bar and more time to worry about things other than gear selection.

XTR Di2 shares its crank, cassette and chain with Shimano’s recently announced mechanical XTR M9000 groupset, so that means Di2 options for single, double and triple transmissions.

Individual components

RD-M9050 rear derailleur

The new M9050 rear derailleur does a great job of hiding away its motor, which is 50 percent more powerful than the one you’ll find in Shimano’s road Di2 derailleurs. That’s to combat the additional weight that muddy conditions can add to the components.

Just like its mechanical brother, the RD-M9050 has Shimano’s 

Shadow RD+
 clutch retention system. This means a rider can externally adjust the spring tension of the rear derailleur using an Allen key. The beauty of this is that with a motor controlling the shift, the tension at the clutch can be turned up to a level that would normally compromise shift performance for a mechanical derailleur.

The derailleur will be available in a short- and long-cage option, with the former weighing a claimed 289g.

FD-M9050 front derailleur

The XTR Di2 front derailleur is less subtle than its rear counterpart. It has a claimed weight of 115g and features the same auto trimming technology as the company’s Di2 road components.

SW-M9050 shifters

Thanks to Syncro Shift functionality, XTR Di2 can be set up to run with either one or two shifters at the handlebar, even with a triple crank. The shifter isn’t really a shifter, it’s simply a switch that's been given a short yet positive throw to try to replicate the feel of a conventional unit. The claimed weight is 64g per unit.

SC-M9050 system display

The brain of this groupset is a small handlebar mounted LCD display. While riding, the display communicates essential information such as battery level, gear position and shift mode (whether or not Synchro Shift is activated). It's integrated with Fox’s electric iCD suspension adjustment system – where the bottom right of the display includes an element which shows the suspension mode of a compatible fork and shock. It certainly leaves the door open for nerdy types and perhaps other manufacturers to exploit in the future.

The display also functions as a charging point for the system and a connection to Shimano’s E-tube software, where – just like in Shimano’s road applications – riders can customise a wide range of functions.

Battery and wiring

Bottle cage mount will not be the only option (L) – notice the wires emerging from the head tube (R)

The battery unit as well as the wiring for XTR Di2 are identical components to the ones used in Shimano's electronic road groups. The battery can be mounted on a bottle cage, in a seat tube and can even be contained within the steerer unit of certain forks (although full details on this haven't yet fully emerged). 

Pricing

Di2 technology has, just like it did for the first generation in the world of road, debuted at the top-end of Shimano's mountain biking range. The pricing alone is likely to keep these parts out of the hands of anyone other than Shimano-sponsored athletes and the very wealthy. 

  • Rear derailleur — £429.99 RDM9050GS (short cage) and RD9050SGS (long cage)
  • Front derailleur — £269.99 FDM9050
  • Right shifter —  £149.99 SWM9050R
  • Left shifter – £149.99 SWM9050L

Stay tuned to BikeRadar for our first ride impressions on XTR Di2 soon.

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