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It's getting on for 10 months since we took our first look at the new 9100 series XTR (ASO 2018). The process of bringing these new parts to the market hasn't been straightforward, and Shimano suffered a number of setbacks along the way. Some parts, such as the unique Scylence rear hub and optional 11-speed cassette, have been delayed indefinitely. Most issues have revolved around the move from prototype stage to full-scale production, but new cranks were delayed by a fire that struck their surface treatment factory. It’s certainly been a rocky road. With all these issues now consigned to the past, we’ve been able to spend some proper trail-time on a full productionready M9100 drivetrain.

XTR Recap

As it's been a while since it was announced, let’s take a quick look back at what this new gear is all about. While they’ll still offer a 2X option with a unique single paddle mechanism, the M9100 is the first Shimano group that's been designed from the ground up as a wide-range 1X system. Sure, Shimano offered 1X chainrings that could be paired with an 11-42 cassette when

M9000 XTR was released in 2015, but their focus at the time was largely on multiple chainrings and close-step gear ratios. In the meantime SRAM forged ahead with their dedicated 1X set-ups, making the jump to 12-speed in 2016. They now have four 1X12 drivetrains in their line-up, and based on sales, riders have been lapping it up. As is often the case, Shimano sat back and observed before releasing their own uniquely engineered products. However, some suggested the setbacks that occurred between the initial launch and the final production release were as a result of the new XTR being rushed to market. Of course, the opposite is likely to be true. Shimano isn't the sort of company that uses the consumer as a guinea pig, so they weren't going to release any products that they weren’t entirely happy with. 

Micro-Spline

We did have a brief play with the new brakes, but here our focus will be on the drivetrain - after all, it's the area that's undergone the greatest change. A key component in the move to 12-speed is the new cassette and freehub system. Dubbed Micro- Spline, it's Shimano's first major departure from the HG freehub body. As the name suggests, it's quite a bit smaller than the older design which makes room for the 10-tooth cog - a key part of achieving a super-wide gear spread with a 1X system. The new spline design also allows Shimano to make the freehub from aluminium without encountering gouge marks on the body. This was actually the reason behind the M9000 XTR freehubs were made with titanium. Initially, the new freehub standard was limited to Shimano and DT Swiss hubs. Of course, a wide range of hubs utilise a DT freehub – from Giant to Bontrager and many others – so the options are broader than you'd initially think. Since then, other aftermarket brands have released Micro-Spline freehubs, including Industry Nine and White Industries, and the options will no doubt increase over the coming years.

Where SRAM machines their top-end cassettes from a single block of steel, Shimano makes the XTR cassette from a range of materials. The three biggest cogs are aluminium, the next five are titanium while the smaller cogs are steel. All of the larger cogs mount via a carbon composite spider. The smallest cogs extend past the end of the abbreviated Micro-Spline freehub, and it's all held together by an extended lockring that's tightened using a regular HG cassette tool. One important to note - the cassette comes with a thin nylon washer that slips between the cassette and the freehub. If this isn't installed, the cassette will creak under load. Our 10-51 cassette tipped the scales at 374g, only 14g more than a SRAM Eagle XX1 cassette. Shimano also offers a 10-45 option for those who want to shave grams and prefer to have closer-spaced ratios (look to the gear ratio table to compare the options). 

Derailleur

At 243g, the XTR derailleur is 22g lighter than its XX1 Eagle counterpart. Like most other Shimano deurailleurs, it features a clutch to assist with chain retention, but the jockey wheels are bigger (13-tooth) and it's offered in three different cage lengths. The longest one, which was the one we tested, works with both the super wide-range 10-51 cassette as well as the 10-45 'rhythm step' cassette. The shorter cage derailleur only works with the 10-45 cassette but offers improved ground clearance. It was also meant to run with the 11-speed M9100 but it seems Shimano has pulled the pin on that option. Finally, the M9120-GS derailleur is specially designed for the 2x12 drivetrain.

Triggers & Remotes

At the other end of the gear cable, you'll find a re-designed trigger. The most noticeable feature is the grippy rubber pads on the levers, but the directmount i-Spec fittings have also been revamped. They now offer a broader adjustment range called i-Spec EV. Thankfully, there's still a tidy looking clamp-on option that allows you to run XTR triggers with non-Shimano brakes. We predict that most Aussie buyers will opt for the 1X12 drivetrain as opposed to 2X12, so for the left side of the bars, Shimano has an i-Spec EVcompatible dropper post remote. It offers the same lever feel as the XTR triggers to make for a matchy-matchy cockpit. With the MT800 dropper remote, the cable clamps at the lever end, so it'll adapt to most cable actuated droppers. The i-Spec-only mounting system means you'll need to look elsewhere if you aren't running the latest Shimano brake levers. 

Cranks

Up front, the new XTR cranks use the same construction method as their higher-end Dura-Ace and Ultegra road cranks. Each arm is forged in two halves that are bonded together to form a unified hollow structure. They also feature a direct-mount chainring with a re-vamped narrow/wide tooth profile. It's all designed to run smoothly and quietly with the new 12-speed XTR chain. In a 175mm length, our sample weighed 533g including a 32T chainring but no bottom bracket. That's around 30g lighter than its predecessor but 100g heavier than the carbon fibre XX1 Eagle DUB cranks and some of the other super light options, such as the RaceFace NEXT. Rather than using a dual pinch-bolt setup that doubles as the pre-load adjuster, as with the M9000, the left-hand crank bolts directly onto the spindle, while a self-extracting design allows for tool-free removal. Bearing preload is now managed via an independently adjustable lockring, and the whole system is built around a 24mm diameter steel spindle - no oversized alloy trickery here! Excluding the bottom bracket, the M9100 drivetrain weighs in at 1,526g, a total of 98g more than the Eagle XX1 equivalent. The cranks are largely responsible for this weight discrepancy, as the remaining components come within a few grams of their SRAM counterparts.

Setup & Shifting

The initial setup was a simple process. We ran it on a boostequipped bike, and the stock 52mm chain line provided trouble-free running. From one side of the cassette to the other, you could backpedal without excessive drivetrain noise and the chain wouldn’t derail, even when prompted by vigorous backpedalling. Non-boost bikes will retain the same 52mm chain line. This could prove sub-optimal, but Shimano says the new chain and tooth profile has been designed to run smoothly across a wide range of angles. I wasn’t able to test it in non-boost format, but I can confirm that the drivetrain showed no signs of complaint on the most obtuse of angles, even when the bike was leaning over to one side. Fine-tuning the cable tension was no different to 11-speed Shimano setups. There’s a good half-turn of the barrel adjuster in either direction before you get any sense of maladjustment. Overall, it seemed to be quite resistant to miss-shifting and slightly less finicky in the initial set-up when compared to SRAM Eagle. Wind the B-tension screw in or out a bit and it still works fine with no hopping or skipping from the chain. I got to try three separate 12-speed XTR equipped bikes and the shift quality was impressively consistent. 

On the Trail

Shimano talks of a 35% reduction in shift lever effort with the new setup, and I couldn’t really pick the difference in this regard. To me, the shifting feel was much the same as the 11-speed gear, and that’s a good thing. I’ve never had anything but praise for the M9000 drivetrain. To retain the same action but with a broader 12-speed gear spread is to be commended. As with its predecessor, you can up-shift either one or two gears with a single press of the front Rapid Fire lever. Shimano has tweaked the new trigger to make the notch more prominent on the second click, avoiding inadvertent and irritating double-shifting. This change was subtle but detectable, and I felt it was a worthwhile refinement. For me, the best thing about the new triggers was the rubber pads and the overall ergonomics. I found them to be grippy, comfortable and the shift action was totally intuitive. With the jump to 12-speed, Shimano has re-vamped the profile of their shift ramps. It's now called 'Hyperglide +'. Their shifting has always been super smooth under load when engaging a lower gear, but the new system aims to smooth out the up-shifts when you grab a higher gear under pressure.

Upshifting still isn’t silent (it sometimes is when shifting to a lower gear) but there was a sense of constant engagement throughout the shift. It's as if the chain maintains constant contact throughout the movement. It allows you to slam into a higher gear under load without feeling like the drivetrain is being tortured. Looking at the ratios provided by the 10-51 cassette (check the gear ratio comparison table), you’ll find the gear steps are mostly the same as SRAM Eagle. From the 10-tooth cog up to the 28-cog, eight of the ratios are identical to Eagle. The next four cogs differ slightly, but I really couldn’t pick the difference between XTR and SRAM Eagle. Having a 51-cog provides a gear that’s 10% lower, but once again, I can’t say that it made a noticeable difference. Having only clocked a few hundred kilometres, we can't make judgement on the longevity of the new drivetrain. There's certainly some scuffing on the three larger alloy cogs, but nothing to comment on as far as chain stretch is concerned. I've always been impressed at the durability of SRAMs upperend cassettes, due in large part to the fact 11 of the 12 cogs are machined from a single steel billet. It'll be interesting to see if Shimano can achieve equally impressive longevity and performance with their mix of exotic materials.

Dollars & Sense

XTR is Shimano’s flagship line, so it’s never going to be cheap. This is Shimano's latest technology, and you’ll always have to pay to get it first. That said, it fares pretty well when compared to SRAMs top-end Eagle XX1 gear. The right-hand trigger retails for $179, the rear derailleur is $345, the cassette is $499 and the chain goes for $99. Pricing will of course vary depending on where you buy, but most of these items are around $30-40 less than their Eagle counterparts. At $495, the alloy XTR cranks will save you over $200 when compared to the lighter XX1 DUB cranks. Overall, it’s realistically priced for a no-holds-barred top-end drivetrain. For those who don’t want to pay top-dollar and don’t need the latest and greatest, my advice would be to sit back and wait. I wager that Shimano will be releasing a far more affordable XT variant in the nottoo- distant future. Experience suggests that the second-tier gear will perform 95% as well, only weigh a handful of grams more and cost a little over half as much. If this proves to be the case, the future is looking extremely bright for Shimano.

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