Shimano 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.