Late to the party, but not empty-handed
“Better late than never”, or so they say. Sure, Shimano is a bit late to the 12-speed mountain bike drivetrain party, a market completely dominated by SRAM Eagle for the last couple of years now. Shimano has never been quick to jump on the next bandwagon, but I can’t help but wonder if they are feeling the financial sting, watching while SRAM runs away with a massive chunk of drivetrain sales.

The recent release of Eagle AXS wireless electronic shifting only adds salt to that wound. Thankfully, it’s not my job to worry about that! I’ll be the first to admit that I was a very early adopter of SRAM’s 12-speed Eagle drivetrain. While it seemed totally ridiculous at the time to have a pie-plate 50T cog on my cassette, I quickly learned that it was actually quite nice, and that I never wanted to go back to a drivetrain with a shallower range. That means Shimano has been totally out of the running for me when I’ve built my new bikes over the last couple of years, which is a shame, seeing that Shimano really does make a quality drivetrain. But all of that is about to change, with the upcoming release of their LONG-awaited XTR M9100 component lineup. Just like SRAM Eagle, it’s a 12-speed drivetrain, and it’s got a nice wide range of gears.

For those who have been keeping up, you likely know it's been quite a rocky road for Shimano to get this new component line to reality, with multiple setbacks and production delays. And yes, it is somewhat overshadowed by SRAM's exciting new Eagle AXS wireless electronic system. But there are still plenty of folks out there who don't want to mess with programming a drivetrain or recharging batteries, those who just prefer a nice quality drivetrain with good old-fashioned cables and housing. That's where Shimano's new XTR M9100 drivetrain fits in, and it competes directly with SRAM's XX1 Eagle (cable) drivetrain. 

Go wide or go home
Shimano knew that many folks share my sentiment of the wide gearing range offered by SRAM Eagle, so they stepped up to the plate with a whopping 10-51T range on the M9100 “Wide Range” cassette. For those with a keen eye, that’s a 510% gearing range, which slightly edges out SRAM Eagle by 10%. SRAM Eagle cassettes have a 10-50T range, which is just one tooth shy of the XTR cassette. How much will you actually notice that on the trail? Probably not much to be honest, and it’s likely more of a ploy on Shimano’s part to one-up SRAM. Interestingly enough, Shimano is also offering another cassette option for those that aren’t sold on the massive wide range of gears. Dubbed the “Rhythm Step”, this cassette’s range is reduced to 450%, with a 10-45T range. I see this mainly being attractive to the XC-race crowd who are looking to save weight anywhere they can. Not only is the cassette lighter, but it also reduces the length of chain needed to wrap the cassette, which also saves a bit of weight, and also allows the use of the shorter cage "GS" rear derailleur. If gram-counting is your MO, and you don’t need the wide range, this will be your ticket.

Shimano claims the XTR Wide Range cassette offers smoother transition into the largest 51T cog compared to Eagle, mainly because of how they spread out the gear range.

As you can see from the numbers highlighted in green, Shimano opted for a more even spread between gears 9, 10, 11, and 12, with the biggest jump being between 9-10 and 11-12. Notice it’s only a 6T jump though, compared to Eagle which as an 8T jump from gears 11-12. While I’ve never really found it to be much of a drawback, I have heard others complain that they feel the jump to the 50T cog on Eagle is too big, which I can certainly understand. The potential drawback on Shimano’s approach are the bigger jumps between 8-9-10, in comparison to Eagle. If you find that you’re between these gears frequently, you may prefer the shallower steps on SRAM Eagle.

The XTR M9100 cassette, sporting aluminum, steel, AND titanium

Another topic worth discussing on the M9100 cassette is the claimed ability to shifter under heavy load with little degradation of shifting performance. This is in-part thanks to an update in ramp design on each cog. Shimano is calling it Hyperglide+, which builds upon and improves the previous Hyperglide technology employed on the company’s cassettes since 1988.

Another benefit to Hyperglide+ is the addition of down-shift ramps, which is a first for Shimano. Instead of just “dropping” the chain down the next cog when down-shifting, the added down-shift ramps allow a much smoother transition. All of this comes together to provide very smooth and crisp movement between gears, both up and down the cassette. Hyperglide+ tech is also employed on the M9100 chain, which has been updated to increase chain retention. This improved chain retention is required due to the more extreme angles the chain sits at on either end of the Wide Range cassette. The M9100 chain also gets a quick-link, an addition we’ve seen Shimano introduce recently on their 11-speed chains (FINALLY!), allowing for tool-free installation and trail-side maintenance.

Construction of the cassette employs “Beam Spider” technology, which conjures up an image of a laser-shooting arachnid in my mind. Alas, neither spiders nor lasers are used in the construction of this cassette. Instead, “Beam Spider” is just a oddly named buzz phrase describing the strategic use of aluminum, titanium, and steel materials for the gear clusters, which are attached to an alloy carrier. To be exact, the three largest cogs are aluminum, the next five are titanium, and the smallest four are steel.

MicroSpline enters the arena
Achieving the expanded gear range of the Wide Range cassette required that Shimano update their freehub design. A 10T cog simply would not physically fit on a standard HG driver, so here we are, onto another new standard. Unless you’re brand new to the mountain bike world, you likely are aware, and fed up with, the rate at which new standards are introduced, strongly encouraging us to upgrade and buy new parts for our bikes. I suppose I shouldn’t complain seeing that it’s a contributing factor in how we make money here at Fanatik, but I can’t help but feel for the consumers out there on limited budgets. Heck, just trying to sort through all the standards of components is an absolute nightmare for the newcomers to this sport. Anyhow, that’s enough ranting, and chances are, if you’re considering XTR, you’re likely not on a super tight budget and/or building up a new bike from scratch.

MicroSpline is Shimano’s new freehub, which will likely replace HG as XTR tech trickles down through XT, SLX, etc. The freehub utilizes 23 splines, which is significantly more than the 13 splines used on the HG freehub. This disperses the cassette cog load more evenly around the cassette. Heavier riders, and those putting down serious force in their high gears, would often find that the smaller cogs would mar up HG freehubs, sometimes to the point where you couldn’t even remove the cassette cogs without some serious force. The MicroSpline system promises to fix this issue, which I am glad to see.

One concern I had with MicroSpline from the get-go was the seemingly limited aftermarket hub options. The original press release from Shimano stated that only DT Swiss would be licensed to build hubs using the MicroSpline freehub. That would leave only Shimano and DT Swiss for hub options, which would be deal-breaker for many seeking other hub brands. Thankfully, we now know that Industry Nine is on board to build MicroSpline hubs, which expands your options. Onyx is reportedly close to releasing on a new rear hub that will be using DT Swiss drivers, which means that hub will also be able to accommodate MicroSpline. I imagine it’s only a matter of time before we see the likes of Chris King and Hope on board, though I cannot confirm that.

Derailleur and shifter
It’s easy to take these bits for granted, which is funny because these two components likely have the most R&D and technology dumped into them. That said, you just expect them to work in this day and age. One thing is for sure, the derailleur is a beauty. I’m a bit of a sucker for sharp lines, and I find metal to be aesthetically pleasing - both of which the XTR derailleur delivers on. It’s not all looks though - Shimano claims they’ve reduced overall noise by reducing pulley tension and adding a rubber bumper on the inside of the cage to cushion any chain rub.

Sleek lines on the XTR M9100 derailleur

The shifter gets the nifty addition of a little rubber grip pad on both shift levers. I’ve definitely experienced my thumbs slipping off paddles from time-to-time, so I can see this as a useful feature. For downshifts, Shimano’s 2-Way Release feature allows you to use either your thumb or index finger. You can also downshift two gears at a time by pushing your thumb past the first click into the second click. It does require a bit more pressure on this shifter compared to previous Shimano shifters, so as to avoid accidentally double downshifts. For single shifts, Shimano claims a 35% reduction in shifting effort, which I’ll take with a grain of salt. I’m always wary of these sorts of claims, and whether or not anyone can actually notice. That said, 35% is a pretty big number, and I will say that the shift-feel of the new XTR is smooth and requires very little thumb effort. But who knows, I’ve been hitting the gym lately, so maybe my thumbs are just stronger!

The I-Spec EV shifter on the left, and the standard-clamp shifter on the right

I-Spec has been updated to a new system (dubbed EV), which is not backwards-compatible with previous I-Spec. The new system offers 60-degrees of rotation adjustment, and 14mm side-to-side adjustment, both improvements over the previous I-Spec.

Breaking old habits?
I’ll be the first to say I’ve never been a fan of Shimano brakes. I’ve ridden a few sets of Shimano brakes in the past, including one set of XTR M988, and they were a non-stop headache. My biggest gripe is the lack of modulation, and the on-off feel of Shimano brakes.  And what the heck is the “Free Stroke” adjustment - which has never seemed to make any significant difference in pad contact - adjusted with a tiny Phillips screw? Phillips screws, in my mind, belong on MTB components from 1998. I’ve ridden just about everything out there, from Magura, to Hope, to SRAM, and I’ve settled on SRAM Code brakes as my go-to stoppers for all my mountain bikes. That said, Shimano has made some updates to the XTR brakes, promising better modulation and more power.

The XTR M9100 2-piston brake caliper

They’ve also got two versions, one with a four-piston caliper (M9120), and one with a two-piston caliper (M9100). It probably goes without saying that the four-banger is targeted to the enduro crowd, and the two-piston targeted at the XC riders demanding lighter weight. The M9120 offers up a tool-free lever reach adjust knob, as well as the Free Stroke adjust...and yes, it’s still that dreaded Phillips screw located on the lever body. I would have really liked to see Shimano rethink this, and make it a tool-free adjustment, like almost all other high-end brakes out there. Maybe next time. The Ice Tech Freeza rotors make their return to the new XTR lineup, and they certainly look the part. With a very clean and pro look, Shimano claims they dissipate heat 20% quicker than the previous Freeza rotors. All in all, I’m stoked on these rotors, but I wish that Shimano would just buck-up and make a six-bolt mount option.

If only it came in a six-bolt mounting option...

The hub that almost was
Along with the revamped XTR lineup and new MicroSpline system, it would make sense that Shimano revisit their hubs, and refresh those as well. They did just that, showing off a completely new XTR hub with an innovative nearly-silent driver system, dubbed Scylence. Sadly, Shimano has had to put an indefinite hold on these hubs due to issues in testing, so we won’t be seeing them any time soon. Shimano still seems to be limiting their patent on MicroSpline as well, so as far as I know right now, we’ll only be seeing DT Swiss, Industry Nine, and Onyx as options to mate up to the XTR M9100 cassette. It would seem a wise move on Shimano’s part to just open up this patent, especially seeing that they themselves don’t even have a compatible hub.

A little more bad news…
While we’re at it, we might as well get this out of the way as well. Shimano’s XTR M9100 crank has also been delayed, though not indefinitely like the hubs. A production fault has delayed the XTR crank out to June/July. In the meantime, Shimano is shipping a non-series all black MT900 crank. No bells/whistles on this crank, and it certainly doesn’t look as cool. But it is an option at least, and for a short while, will be the ONLY option. Unfortunately the new chain is NOT compatible with existing aftermarket chainrings from Race Face, OneUp, Absolute Black, Wolf Tooth, etc. To further clarify that point, the chain itself will wrap around these chainrings no problem, however, it's the quick-link that Shimano implemented on the XTR M9100 chain that causes the incompatibility. The quick link itself has been narrowed slightly, which means it won't fully seat itself on existing aftermarket chainring options. I have heard rumors that replacing that Shimano quick link with a KMC quick link will resolve this, though I'm not sure I can really recommend doing so. Aftermarket companies are reportedly working quickly on new chainring options that will be compatible with Shimano’s XTR M9100 chain, as well as their new direct mount system. Until Shimano officially makes the M91000 crank available, I’ll hold off on going into any more detail on it, and instead, I’ll just put this nice sexy photo right here for ya, so you can know what you can’t have right now.

The best-looking XTR crank to-date, and it's finally got a direct-mount chainring!

It’s not all bad!

It’s unfortunate that Shimano has had a bit of a rocky road to releasing this new XTR line, but all in all, it’s the drievetrain that really stands out to me the most with XTR M9100. Yep, it is massively late to the game - and even still, we won’t be seeing it really start to flow until mid-May, with XTR cranks delayed until June/July. That said, it’s really the derailleur/shifter/cassette/chain that makes up the guts and glory of this new driverain, and it will mate up to aftermarket cranks/chainrings in the not-so-distant future. Looking for an alternate option to SRAM Eagle? The XTR M9100 drivetrain is certainly a worthy competitor. For those who are willing to wait, we are offering preorders on XTR M9100 components on our website. You can also use our Bike Builder to assemble your next XTR-equipped dream sled.