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ShimanoXT CS-M8100 12-Speed Cassette


Item # SHIU189

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Item # SHIU189

XT CS-M8100 12-Speed Cassette

Fancy drivetrains like XTR may get the first hit of sleek new technology, but fortunately for us, Shimano doesn't lag when it comes to trickling the tech through the lineup, which is easy to see with the new XT CS-M8100 12-Speed Cassette. The new 12-speed XT cassette comes with a complete makeover from its 11-speed predecessor, with Shimano's new Beam spider for weight reduction and better power transfer, balancing aluminum and steel for the perfect blend of rigidity, durability, and weight savings throughout.

Shimano's new 12-speed cassettes are available with two different gearing options — the 10 - 51-tooth Wide Range option, for a massive gear range that gets you up the steepest fire roads with ease, while maintaining serious power for hammering to the front of the pack, or the Rhythm Step cassette with a 10 - 45-tooth range, designed to give more options for those of us who struggle to find the perfect gearing on a ride, or want the flexibility to run one-by or two-by cranks. Both cassettes are designed to offer the best mountain bike shifting available, with redesigned chain plates and shift ramps that pair together to guide the chain up and down the cassette with faster, smoother shifting, and better engagement to reduce the chance of dropped chains.

With the stretched cassette range, Shimano needed to craft a new freehub design to accommodate the smaller 10-tooth cog that wouldn't fit on the previous HG freehub, and so the Micro Spline freehub was born. Micro Spline works seamlessly pairs with the new cassette, and drops weight down, while keeping engagement precise and snappy. It's built from aluminum, and features smaller, more widely distributed splines that limit cog damage for long-term use and durability. While the XT cassette packs the same gear ranges as its XTR sibling, its construction skips the featherweight titanium, so it does scale in a little bit heavier than its partner. It makes for an ideal choice for riders who are looking for top-level quality, and massive gear ranges, at a more pocket-friendly price point.

  • Take on a gear for every pitch with Shimano's new XT cassette
  • 12-speeds offer a huge range for every kind of riding
  • Wide-range cassette sets you up with a gear for steep climbs
  • Opt for Rhythm-step cassette for 1x or 2x compatibility
  • Cassette offers the range of XTR without the price
  • Only compatible with new Micro Spline freehub body

Tech Specs
Cog Sizes[10-45t] 10, 12, 14, 16, 18, 21, 24, 28, 32, 36, 40, 45, [10-51t] 10, 12, 14, 16, 18, 21, 24, 28, 33, 39, 45, 51
Cog Materialaluminum, steel
Carrier Materialaluminum
Hub TypeHyperglide+
Recommended Usemountain biking
Manufacturer Warranty2 years

What do you think about this product?


>Rating: 5

Yes the 12 speed xt drivetrain is great

I've put it through the wringer

I have this particular drivetrain on my pivot 429 it's oem..I also have a sram 12 speed on a rip-mo and sram 8 speed ex1 on my e-bike. Just sold my last 2 by m8000 11 speed two by on a older tall boy. While my bike guru thinks sram are superior I must object! Put a.shimano and a sram cassette under a microscope and it's immediately apparent just how the metallurgy compares. Shimano resisted 12 speed one bys beyond the reasonable for the simple reason is that they knew how much more wear a 50/51 tooth alloy cog will wear when compared to a 42 tooth on a 11 speed and even that they resisted because in their mindset 36 teeth sounded adequate. It was only after they nearly had to give away 2 by drivetrains AND the reconfigured geometry of a slacker head tube and shortened chainstays created a near impossible functioning front deraillier literally forced them to take action to protect their basic business. And the above reviewer from Utah when runs his with a 32 tooth front obviously is extremely young and super fit because in order to trump.a 11 speed 2 by which normally isnset up front 34/24 and rear 11-42 u need 28 teeth on a one by. Only now is it cobble together a 28 tooth front if your bike came say for example with a cinch front chain ring ( race face doesn't do a 28 12 speed front chain ring though they promised me it's coming ) wolf tooth just added one and I'll install mine very soon. Old geezers like me emphasize climbing....youngsters don't care how they get up as long as the descent is rad.

>Rating: 5

Soooo Smooth

I've used it several times

I had about given up on Shimano but with the release of their 12-speed SLX and XT groupsets, they once again got my attention. Over the last few years my bikes have always had Shimano XT drivetrains, I've gone from a 1x10 to 1x11 and now 1x12. They nailed it with the 1x12. Yes, it took them quite a few years longer than SRAM but the wait was worth it. I am running the 51T cassette with a 32T chainring out here in Utah and that gives me all the range that I need. Right away I was climbing more efficiently and quicker than on my old 1x11 setup. So you might be asking, Why go with Shimano over the competition? Well, Shimano's Hyperglide+ design is the main thing that sets them apart. With this design you can now shift whenever you want. No need to unweigh the pedals slightly during a shift to prevent the chain and cassette from making terrible noises. The chain will move up or down the cassette without any fuss. It still seems strange to not ease up on the pedals before shifting but you can and the drivetrain is happy to get you into the gear you want. So there’s that, and with Shimano you still have the ability to drop down two gears with one push. I love that feature and use it often. I’d say if you do not care about having the absolute lightest drivetrain setup then you will be very happy with Shimano XT for the money. Shimano XT has always been a great bang for the buck groupset and that remains true with the 8100 series. Pros: Shimano Shifters (Rapidfire Plus and I like shifting with my index finger), buttery smooth shifting up and down, quiet, easy to setup, the performance you get for the price.. There's even a mark on the inside of the pulley wheel cage to simplify setting the correct B-tension. Cons: A little heavier than SRAM GX. A con that I will happily live with for getting a better shifting drivetrain for less money. You need a MicroSpline freehub for the cassette. It was an easy swap for me with an I9 freehub. In the future MicroSpline will be much more common on new wheelsets so this will be less of a problem.

>Rating: 5

Truly Amazing

I've used it several times

I was able to throw the XT 12 speed drive train on my MegaTower a couple weeks ago now and man does it know how to hold its own! What I noticed right off the bat is the set up was very simple! It only took about an hour to get it up and running. There are some amazing little details to the 12 speed components as well! My favorite being the rubber pad on the shifter for more traction (most companies leave it as polished alloy, which can be very slippery). After getting the first few miles under my belt I noticed how dead silent the shifting actually is! I would have to look down to make sure I did in fact shift, and it was always spot on. The other aspect that really has me excited about this stuff is that you can confidently shift under load. I have run Eagle drive trains on previous bikes since Shimano had not released a 12 speed group set yet, but I'm stoked they took their time, because they nailed it right off the bat! Pros: - Easy setup - Dead silent shifting - Ability to shift under load -Attention to detail (the little things that just make it easy to use) Cons: - It isn't the lightest 12 speed setup out there - Visual Design wasn't a big focus (is not a piece of art like xx1 Eagle)

>Rating: 5

This one goes to 51!

I've put it through the wringer

A breeze of an install! Make sure you have the "Microspline" driver on your wheel, as well. The old Shimano HG won't work on this 12 speed, M8100 stuff. Cool design on how they got the 10 tooth cog attached too! I like the lower end gearing of the Shimano cassette compared to the SRAM Eagle stuff. It is a bit more consistent in the jumps between cogs instead of ramping up to the 50/51 tooth. The last cogs on Eagle gearing go: 28,32,36,42,50 And on XT they are: 28, 33, 39, 45, 51 With Eagle your jumps are: 4, 4, 6, 8 And on Shimano you get: 5, 6, 6, 6 I feel this most when I am starting on a climb and am slowly gearing down. With Eagle, you can hit a bigger jump and spin out for second until your bike slows down. With XT I don't feel that. Also, when you are accelerating or heading down with XT, you get a little more consistent jumps as you gear up and gain speed. No feeling like you all of a sudden are pedaling in the mud.