Shimano XTR Di2 M9050 electronic groupset – just in

The Shimano XTR Di2 M9050 electronic groupset is arguably the most hotly anticipated mountain bike product for 2015. We've sat in on the presentations, we've ridden it a few times, we've ogled over prototypes – and now we finally have a complete production grouptest in our grubby little hands. Read on for actual weights and additional technical information, and be sure to click through the gallery for more detailed images.

XTR Di2 RD-M9050 rear derailleur – 290g, US$650 / £429

Shimano has done an admirable job of tucking the bulky motor out of the way on the new XTR Di2 rear derailleur, both physically and aesthetically. While it's impossible to miss the protrusion hanging off of the back of the derailleur that houses all the electronic guts, said protrusion is tucked inboard for protection during a crash. And instead of looking like those bits were simply tacked on after the fact, the lower part of the housing is integrated into the forging for the upper knuckle.

Meanwhile, Shimano has moved to hex-head set screws to adjust the upper and lower limits instead of its longstanding Phillips-head format, which further cleans up the appearance.

Up front, the Shadow Plus pulley cage clutch mechanism finally gets an external port to access the tension band. The toggle switch to turn the clutch on or off is now more prominent and easier to use, too.

Finally, it's worth noting that while the Di2 derailleur's extra hardware adds weight relative to the mechanical version, the penalty is impressively minimal at just under 70g.

XTR Di2 FD-9050 front derailleur – 113g, US$425 / £269

The Di2 front derailleur is certainly larger than a conventional changer but it's cleanly integrated into the rest of the structure and doesn't look out of place. The low profile doesn't protrude out from the frame any further than the cage while the rounded lines helps to minimize the visual bulk.

The XTR Di2 front derailleur weighs about 40g more than mechanical XTR.

Shimano is producing just a single Di2 front derailleur configuration to fit all frames – just bolt on the appropriate adapter for high/low clamp or high/low direct mount. This makes things easier for shops and mechanics but it also builds in some safety for Shimano's engineers. Should yet another mounting standard come about, it's entirely possible that the company will only have to release a new bracket.

XTR Di2 Firebolt SW-M9050 shifters – 129g per pair, US$500 / £298

Freed from the restrictions of pulling and releasing prescribed amounts of stainless steel cable, Shimano has moved to a rotary-style movement for the new XTR Di2 'Firebolt' shifters that the company says feels more ergonomic and natural. As compared to road Di2 shifters, these have a refreshingly 'clicky' feel with lots of tactile feedback along with just enough throw to reassure your fingers that you've actually done something.

The fit can be further fine tuned with sliding each thumb paddle left and right.

At their essence, however, the shifters are nothing more than electronic buttons – which means that they can be programmed or used in any number of different ways. Would you like to operate the rear derailleur with the right-hand shifter? How about swapping the functions of the upper and lower paddles?

We have both shifters on hand but ultimately we plan on using just the rear for the sequential Syncro Shift setup. What's Syncro Shift, you say? It's Shimano's sequential shift program map, which automatically controls both the front and rear derailleurs with a single shifter to provide relatively evenly spaced gears throughout the entire range.

XTR Di2 SC-M9050 display unit – 30g, US$150 / £TBC

Mounted on the bars just next to the stem is the SC-M9050 display unit, which indicates not only current gear selection, shift map, and rough battery life but also your suspension mode should you decide to pair the system with Fox's iCTD fork and rear shock. (Conveniently, we have this on hand.)

The LCD screen also makes it easier to fine tune the derailleurs on the trail while extra e-tube wiring ports on the back provide expansion options for other components as they become available. Last but not least is a charging port hidden away on the side behind a rubber flap.

SM-BTR2-1 battery – 51g, US$160 / £100

As with Dura-Ace Di2 and Ultegra Di2, XTR Di2 can be powered by several different battery options. We've chosen the slim SM-BTR2 battery, which tucks away inside the frame and can be recharged through the port on the SC-M9050 display unit. We've gotten months of use from the same battery pack on the road but given the greater power draw of the added suspension components, we expect to have to charge things up more often this time around.

XTR Trail FC-M9020-2 crankset – 657g, US$600 / £TBC

Although 1x drivetrains are in vogue, we opted for the dual-ring XTR Trail crankset for our test – partially because that's all Shimano has on hand at the moment. That's just as well, though, because the dual chainrings will give us a chance to test Shimano's slick Syncro Shift.

The crankset itself has drawn criticism for its polarizing appearance, which is more curvaceous than previous XTR generations and uses a brand-new, asymmetrical four-bolt chainring pattern. That said, it's hard not to get drawn in by the sleek lines and some of the clever engineering hidden within.

Shimano uses its clever two-piece, hollow construction technique for the outer ring. Between the molded carbon composite inner half and the deep-section aluminum outer plate, we expect superb bending stiffness, which bodes well for shift performance under load.

Also, those separate bits on the chainring spider that we previously thought might have just been cosmetic turn out to be highly profiled chainring bolt halves.

Shimano is carrying on with its long-standing hollow-forged aluminum crankarms and Hollowtech II layout, whereby the non-driveside crankarm slides on to and clamps around the 24mm-diameter steel spindle.

XTR CS-9000 cassette – 327g, US$350 / £TBC

With the move to 11-speed, Shimano's latest XTR cassette now offers a bigger 11-to-40-tooth spread as compared to last year's 11-36T cluster. Adding a ratio does bring added mass but only just 55g or so thanks to some aggressive weight-saving measures. The largest seven cogs are titanium, and two of the three spider carriers are made of carbon composite.

Shimano has thankfully also managed to squeeze in that extra cog on the same freehub body currently used for 10-speed drivetrains – and not by resorting to a ridiculous narrow spacing, either. Just as SRAM has done with XX1, Shimano takes advantage of the inward angle a wheel's spokes take from hub to rim and cantilevers the biggest cog over the hub flange, thus making use of otherwise wasted space.

We'll see how well this multi-piece setup holds up in terms of creaking and durability but either way, this is one area where SRAM still holds a distinct advantage. In comparison, the XX1 cassette not only offers more range but it's lighter, too.

XTR CN-HG900-11 chain – 258g, US$60 / £TBC

Shimano hasn't developed a new chain specifically for XTR, instead opting to spec the same model as on the road-going Dura-Ace package. Asymmetrical plates supposedly improve shift performance while a 'Sil-Tec' surface treatment is said to reduce friction by 60 percent and shed mud 30 percent better than an untreated chain.

More important, it's a proven design that has been holding up well so we have high hopes that the same durability will carry over to the trail.

XTR Trail BR-M9020 hydraulic disc brakes – 386g (complete front with 160mm rotor), US$358 / £230

While the new XTR Race brakes are lighter with their magnesium lever bodies and reduced feature set, we decided to tick all the boxes with the more adjustable and powerful XTR Trail version. Key differences include adjustable pad contact, finned pads to help dissipate heat, and Shimano's clever Servo Wave cam mechanism that boosts power once the pads have engaged the rotor.

The complete weight won't blow anyone's doors off but based on previous experience, we anticipate excellent braking power along with worry-free reliability. Also, the finned Freeza three-layer rotors just plain look cool.

XTR Trail WH-M9020 wheels – 1,718g, US$1,500 / £TBC

Likewise, we opted for the heavier – but more capable – XTR Trail wheels instead of the more competition-oriented XTR Race hoops. Internal width is a relatively generous 24mm with a tubeless-ready profile, and the rim features Shimano's trademark hybrid aluminum/carbon fiber construction.

Rather than change its ways to reduce costs or weight, Shimano is relentlessly sticking to its guns with adjustable cup-and-cone bearings and a titanium freehub body. The former requires an initial adjustment but tends to be more durable long-term (and easier to rebuild) than cartridge bearings while the latter won't scar under load like aluminum freehubs.

External nipples will make for easier truing when needed, too.

We're planning to install of this on Pivot's brand-new Mach 429 SL early next week so stay tuned for first ride impressions – plus some additional images of what should be a cracking build.

For more information, visit www.ridextr.com