It's hard to get surprised in this industry. Whether it's the rumor mills, the spy photos or just good old-fashioned logic, it seems like we always know what's coming. The best we can hope for is that, within the expected, there's something unexpected.

No doubt, you already expected the new XTR (proper nomenclature: "M9100") would offer extra focus on 1x but probably wouldn't abandon 2x. And you must have assumed it would be built around a 12-speed cassette and that it would offer a range that at least matches that of SRAM Eagle. You would be right on all counts. But there's a lot more to it than that, some of which just may surprise you. Below, you will find a lengthy exploration of the nuts and bolts that make up 9100. What you won't find are ride impressions, opinions, or conclusions. Those, we'll have in the coming weeks. In the meantime, let us introduce you to the new XTR.

The Cassettes

First surprise: The cassette-s. As in more than one cassette. There are a total of three unique piles of cogs within the 9100 group, and they're not all 12-speed.

CS-M9100 Wide Range: This is the one we were waiting for: A 10 to 51-tooth 12-speed cassette offering a 510 percent gear range. That extra tooth on the large cog was not added to be a tooth above Eagle, but because Shimano found it offered the most optimum shift gates given the spread this cassette offers. The largest three cogs are alloy, followed by five titanium ones. Those eight cogs are on an aluminum spider and the last four cogs are steel.

I know we just started, but a brief time out for a comparison to SRAM Eagle might be in order. After all, we’ve been waiting a couple years for Shimano to join this fight, and the M9100 Wide Range cassette is the first shot fired. Shimano’s 10 to 51 cassette weighs in at 367 grams and costs $380. For those who are counting, that’s $40 cheaper than XX1 Eagle and just $20 more than X01. And it weighs about 10 grams more than each. That weight might be surprising given that the 9100 cassette features more aluminum and titanium than SRAM’s XX1 and XO1 cassettes, which are all steel save for that 50-tooth ring. SRAM credits its light weight to the billet-machined design that it has been using for over a decade. But Shimano likes its metal forged. Forging preserves the natural grain within the material, and its natural strength along with it. The craft of metal forging in Shimano’s home of Osaka goes back centuries, but that’s another story.

Ok, back to business…

CS-M9100 Rhythm Step: The 10 to 45-tooth 12-speed Rhythm Step cassette addresses the concerns of an admittedly small portion of the 1x user group, which is gear choice. Since the days of 11 to 36-tooth cassettes, the jumps between gears have been widening. Rhythm Step offers finer steps for riders who are picky about their cadence and are satisfied with a 450% gear range. It also serves as a 2x option.

CS-M9110-11 Lightweight: The 10 to 45-tooth 11-speed cassette is essentially the CS-M9100 Wide Range 12-speed cassette without that 51-tooth cog. The "Lightweight" part goes beyond just the cassette itself. While losing the 51-tooth sheds 57 grams, the extra chain links cut out save another 13 grams, and the short-cage derailleur trims 3 grams. The CS-M9110 cassette is also compatible with a specially-designed hub. The hub happens to save 3 grams, but its beauty is in its wider flange spacing.

Because the largest cog on both 12-speed 9100 cassettes domes over the drive side flange, it needs some extra breathing room. Not so on the 11-speed. The 11-speed-specific FH-M9125-B hub's drive side flange sits 4.7 millimeters farther outboard, offering better bracing angles and more even spoke tension. This, combined with the benefits of a shorter chain, a shorter derailleur cage and a total of 76 fewer grams of unsprung weight, might make the M9110 cassette the go-to for XC and enduro racers who don't need the ultra-wide range of the 51-tooth ring. After all, the R in XTR stands for Race, and bailout gears are for the rest of us mere mortals.

All M9100 series cassettes feature what Shimano is calling Hyperglide Plus. The original Hyperglide has been around for 30 years, and it is essentially Shimano's way of designing teeth and chains to minimize or eliminate the moment when the chain is disengaged from one cog but not yet fully engaged with the next. It allows us to shift under more load during downshifts when a climb begins or steepens. But it doesn't address upshifts. The popular onomatopoeic expression of an upshift is "clunk" as the chain free falls to the next smallest cog. Hyperglide Plus aims to make that more of a "woosh" or maybe a soft "thhhh-AK." Until we get to ride it late next month, we can only flip through old Batman comics and imagine the possibilities.

The Freehub Body:

For a brief moment after learning about 9100, I dreamed that Shimano, in a spirit of cooperation and consumer advocacy, would  adopt the XD freehub standard for its new cassette. That would lessen the confusion among riders, ease the stress on wheel manufacturers and simplify the spec on complete bikes. And that dream really isn't so far-fetched. After all, SRAM had been exclusively using Shimano's HG freehub body until it introduced XD. And XD is open source, so why couldn't Shimano use it? Because SRAM's cassette-mounting interface, for which XD was specifically designed, is not open source, and it’s not for sale. That's why.

To use the existing XD standard, Shimano would have to build a new mousetrap based not on what it feels is best, but based on what doesn't interfere with SRAM's patents. That would force Shimano to compromise in ways that are completely antithetical to its philosophy of product development. Shimano prefers an approach of integration and invention, not modular adaptation. And building its own system allowed Shimano to better incorporate its skills with forging to its wide-range cassette.

The Micro Spline freehub body has about the same outside diameter as the HG freehub that we know, but it's slightly shorter to allow the 10-tooth cog to hang off the end. The next-biggest, 12-tooth cog slides onto the splines like it would any traditional Shimano freehub, but its outside face is etched with a unique set of splines into which the 10-tooth cog is keyed. Then, a longer cassette lockring passes through both cogs and threads into the freehub just like we're used to and with the tool we’re used to.

The term Micro Spline doesn't refer to length or diameter, but to the splines themselves. The thinner, more numerous splines mean better-distributed force between the body and cassette. This allowed Shimano, for the first time in its history, to make an aluminum freehub body.

Unlike XD, Micro Spline is not an open-source design. The only brand Shimano is working with is DT, who they also happen to share the Center Lock brake rotor-mounting standard. Most popular, current DT hubs will be able to be retro-fitted with Micro Spline, as can many third-party wheel brands who use DT’s hub designs. There’s no word yet on which other brands might someday license the Micro Spline standard.

Hidden inside the hub is Shimano's new Scylence ratchet system, which we'll cover below in the hub section.

The Chain:

One of the consequences of 1x drivetrains is that we tend to cross-chain more than we used to. In the 2x days, the inner front ring was closer in line with the corresponding easier rear cogs. But today, in the often high-torque moments in low gears, the chain is making quite the lateral journey, only to be forced straight again when it meets the chainring. The flat surface of the chain's roller and flat surface of the tooth's leading edge aren't flush until they meet, which leads to what is essentially a vibration as chain meets ring. The vibration is worst on the wide tooth and wide link. The new CN-M9100 chain offers a unique solution by chamfering and extending the ends of the narrow links into the wide link. This eases the transition from cross-chained to locked-in, lessening noise and power loss. The effect seems minimal, but you can watch and feel it happen if you feel your chain as it enters and exits your chainring. That tiny bit of deflection on every other tooth happens dozens of times per revolution, and countless of times per ride. Shimano claims it adds up.

The Crank:

It's still aluminum. It's still hollow, and it's still a shiny shade of pewter. But the non-drive side doesn't attach with a pinch bolt and, for the first time in XTR history, the chainring doesn't attach with any bolts. The direct-mount ring uses Shimano's own spline, and the lock-ring uses Shimano's own tool … sort of. It's essentially a standard outboard-bearing bottom bracket spline, but no socket-style bottom bracket tool has a large enough hole to slide over a 24-millimeter spindle. For now, tools will be shipping with cranks. The crank's non-drive arm presses onto the spindle exactly like the 970-series XTR and with the same spindle interface. Shimano ditched the double-pinch-bolt it used on the two most recent XTR designs because, as motivates most decisions a bicycle component manufacturer makes, it offers lighter weight and higher strength. In fact, unlike the most recent generations of XTR, 9100 uses the same crankset for XC as it does for enduro. A traditional single bolt presses and fixes the arm to the spindle, while a threaded ring attached to the non-drive arm gets finger-tightened against the bottom bracket to manage play and preload. That preload ring is designed with enough friction against its threads that it doesn't need a pinch bolt like the 970 did.

The crank arms are available with a common, boost-friendly q-factor of 168 millimeters or, for those with non-boost frames or XC-oriented riders who like it tighter, Shimano offers a 162-millimeter option. What doesn't change between boost and non-boost is the chainring. Thanks to the unique Hyperglide Plus tooth and chain shape discussed above, Shimano claims that the 52-millimeter chainline (boost) sprocket can accommodate a non-boost rear end. The only chainring choice you have to make is size, which ranges from 30 thru 38 teeth. Unless, of course, you want to run a double. You probably don't, though. Shimano knows you probably don't. In fact, there is exactly zero out-of-the-box 9100 2x spec in North America. Even in Europe, it's only at around 5%, but there are still riders who want it, so Shimano offers a 28/38 direct-mount ringset in either a 51-millimeter or 49-millimeter offset, and it's only compatible with the 10-45 cassettes.

The Rear Derailleurs:

There's no fundamentally new technology in the 9100 derailleurs, just some tweaks to make them more effective and efficient. The 13-tooth pulleys manage more chain with shorter cages and offer a smoother roll, and the leverage ratio and stroke path have been updated for better precision.

There are also three unique setups to accommodate: 1x 10 to 51, 1x 10 to 45 and 2x 10 to 45. So each setup gets its own derailleur.

RD-M9100-SGS: This model is built around the 1x, 10 to 51 cassette. It's got a long cage to take up the slack and a long parallelogram to reach up to the 51-tooth ring.

RD-M9100-GS: This is also built for 1x-systems, but specifically the 11- or 12-speed 10 to 45-tooth cassettes. It's got a tighter parallelogram and a cage that's more than an inch shorter than that of the 9100-SGS model. At first glance, it's as stout and compact as a downhill derailleur.

RD-M9120-GS: Short parallelogram and long cage, the 9120 derailleur is built around 2×12, so it maxes out at 45 teeth but accommodates the extra chain needed for a double front ring.

The Hubs:

Notice, these XTR hubs are not laced to XTR rims. Shimano has gotten out of the high-end mountain wheel game and is focusing on the parts it does best. The hubs still use Shimano's user-serviceable loose-ball cup-and-cone system, which seems outdated until you use it. You're able to fine-tune the perfect bearing preload rather than hope the sealed rings get you just right. Tuning in the rims is up to you, but you've got a few choices to make first.

M9110 / M9110-B: Standard J-bend flange, 28- or 32-hole. 9110 hubs are available either non-boost or boost (hence the B). Those cutouts on the larger, drive-side flange are there to make lacing spokes into the smaller non-drive flange easier. That flange is smaller to save weight, and it seems to have succeeded. These hubs are within a gram of a set of DT-240s.

M9110-BS: This is Shimano's first time offering a bare straight-pull hub. It's 3-cross only, boost only, and 28-hole only. But it's got that straight-pull cache and the stiffness advantages to boot.

M9125-B: This is that rear hub designed around the 11-speed cassette because of its wider flange distance, offering a stronger, laterally stiffer wheel. Other hubs can also run the 11-speed cassette if need be, but this hub can't run the 12-speed because the largest ring is domed over the flange and wouldn't clear the 4.7-millimeter outboard shift. This is a boost-only hub, available in 28- or 32-hole.

MT900-B / MT900-BS: These are non-series (Shimano-speak for “budget”) versions of the 9110 hubs. They cost just barely over half as much as their richer relatives, and the main penalty is weight. They actually offer most of the same bells and whistles, including Shimano's new Sylence ratchet system.


For those following the rumor mills, Sylence is nothing new. This patent drawing still features a traditional HG interface, but the rest is accurate to what’s inside the 9100 and 900 hubs.  At first glance, it looks much like a DT-Swiss or Chris King system, relying on two ratchet rings engaging all teeth at once for a connection. But what sets Sylence apart is, instead of simply putting a spring behind one of the ratchet rings and letting them buzz across each other while you coast, Sylence keeps the rings separated until you pedal. The outer ratchet ring slides on a helical track attached to the freehub body, and the initial twisting force of a pedal stroke slides the ratchet ring down the helical track and presses it against the stationary one inside the hub shell. The end result is totally drag-free, noise-free coasting and 7.6 degrees between engagement points, or approximately 47 points per revolution. We say "approximately" because the mechanism involved before engaging makes it not as simple as just counting the teeth and dividing it into 360. Either way, that's notably better than previous XTR's 36 points of engagement.

The Shifters:

The 9100 rear shifter claims a decrease in the force and time it takes to shift, though much of that is thanks to the refined leverage in the derailleur. The double-upshift that many of us love so much about XTR shifters has received some tweaks as well. The second upshift takes a little more effort than it used to, so it's harder to accidentally over-shift.

With the flip of a switch, the shifter accommodates either 11- or 12-speed cassettes, much like the double- or triple-compatible front shifters of old. It's also received some updated ergonomics and a broader range of position adjustability. The front shifter uses a unique single lever Shimano calls the Mono Lever. "Mono" means "one" and "lever" means "lever." Push it like you would any other shifter, and it pulls the cable to upshift. Tap it again, whether forward with your thumb or backward with your index finger, and you'll shift back down.

The Brakes:

I’m glad you made it this far, because the brakes may be one of the coolest parts of 9100. As with the previous generation XTR, there's a lighter-duty and heavier-duty brake, in this case XC and Enduro. Each has one of the most innovative design tweaks we've ever seen in a brake lever. Shimano found that the ultra-narrow bar clamp that was used on the M9000 XTR levers lead to some noticeable flex under braking load. So instead of just thickening it up, they moved the clamp inboard, toward the center of the lever body, leaving a separate point of contact just behind the lever blade hinge where the clamp would be on a traditional lever. The new design mandated yet another standard for I-spec, Shimano's shifter/brake integration hardware. While I still haven't ridden these things yet, just wrapping a digit around them and squeezing tells me they’re going to be rad. And of course, there's more to them than the levers.


M9100: The XC brake uses a simple, non-servo-wave lever assembly and is a combination of a magnesium body and a carbon blade. The caliper shaves some weight by ditching the adjustable banjo connection and instead routing the hose directly into the caliper. The pad is slightly smaller as well, but it's an existing pad Shimano uses in its flat-mount road calipers. As long as it's not the finned version, those pads will drop right into the XC XTR. Altogether, it shaved 26 grams out of the entire system, including lever, caliper, and rotor.

M9120: The enduro brake still uses a Servo-Wave lever mechanism and an alloy body, but moves to an alloy lever. The caliper goes to four pistons, which is a given for enduro racers who tend to use Saint brakes. But what you'll often hear about Saint brakes is that they're too touchy. So, the M9120 brakes have a different tune than Saints. Specifically, that different tune is in the track the Servo-Wave lever follows, which is shaped so that the power doesn't come on as quickly. There's a new, sleeker shape to the pad's heat-sync fins, but Shimano’s existing four-piston pads will fit fine, whether finned or not.

The Rotor:

Shimano stepped up its Ice Tech rotor design with the new Freeza rotor. A coat of heat-dissipating paint on the rotor’s exposed aluminum helps drop the temperature by a claimed extra 10 degrees Celsius. Advancements in the 180- and 203-millimeter sizes focused on cooling while the 140- and 160-millimeter sizes were approached with lighter weight in mind. None were named after a Dragonball Z villain. That’s Frieza.

The Pedals:

M9120: The enduro pedal is both wider and longer than its predecessor. It’s built with today’s skate-shoe-style SPD shoe in mind. And for the first time, Shimano is including a cleat spacer for riders to fine-tune the depth of the cleat and better match the pedal’s side support with their particular shoe.

M9100: The XC pedal also widens, but it rounds out those wider surfaces to help push mud off of them rather than trap mud in them. For riders looking to tune their q-factor, Shimano offers a 52- and 55-millimeter spindle for the M9100. The bindings are also offset to widen the one of the channels through which mud can pass when forcing a mud-clogged cleat into its home.

Bits and Bobs:

Front Derailleur: Yes, I buried the front derailleur here in bits and bobs.  There’s nothing significantly new about the 9100 front derailleur, but there has to be one. It comes in direct-mount, e-mount and mid-clamp, and they’re all side-swing style.

Chain Guide: This is a simple top-of-the-ring chain retainer that adjusts with a thumb screw and locks in with a single bolt.

Remote Dropper Lever: A nice-feeling, nice-looking, clamp-at-the-lever dropper remote that works with pretty much any cable-actuated dropper you can get your hands on. But it only works with the new XTR I-Spec, so if you want this lever, you'll need the 9100-series brakes.



OK, I know I said there’d be no conclusions, but we’ve been on a 3000-word journey together. It’s hard not to say some parting words. Again, the real insights will come when we get a chance to ride 9100 in the coming weeks. But from what we can see so far, the new XTR promises to bring much-needed competition to our component spec, especially as it begins its slow trickle through Shimano’s line. But only time will tell. Speaking of time, Shimano is listing fall 2018 for XTR M9100 availability.