Shimano’s new 12-speed mountain bike technology establishes the new benchmark in mountain bike performance and customization. One of the key components in this revolutionary drivetrain design is the cassette, and the benefits of Shimano's latest XTR, DEORE XT, and SLX cassettes are significant.
Shimano’s three premier 1x12 drivetrain systems all boast a whopping 510% gear range if you choose the 10-51-tooth cassette option. That means having the perfect gear whether you’re grinding up a steep climb or hammering at the front of a short track race. However, It's not just the breadth of range that matters most with Shimano's new 12-speed cassettes.
The gear steps throughout the 10-51-tooth cassette are strategically designed for pedaling efficiency and optimal ride feel. The first eight cogs provide comfortable and familiar jumps between the gears (10-12-14-16-18-21-24-28), while the top four cogs (28-33-39-45-51) limit the size of jumps. This is especially noticeable in the last gear change from the 45 to the 51-tooth cog. Rather than offering riders an abrupt and jarring bail-out shift, Shimano's last jump feels smooth, crisp, and natural.
Shimano's HYPERGLIDE+ technology revolutionized shifting performance with the smoothest and most precise shifting for all riding conditions. The 12-speed mountain bike cassettes feature new ramp designs, so whether you’re shifting up the cassette into an easier gear or dropping down into a harder option, HYPERGLIDE+ allows (if not encourages) you to continue pedaling. Gone are the days when you had to back off the gas, then shift, then start pedaling again. Now, riders can make smooth and seamless shifts at any time, and that means less momentum loss, increased efficiency, and no more compromises.
“It’s really changed the way we shift,” explains Nick Murdick, Shimano North America Mountain Bike Product Manager. “Before, we didn’t realize how much we were taking it easy on drivetrains, actually soft-pedaling when we were really trying to accelerate. But now you can shift under load — and it actually shifts better when there is a lot of load because the new Shimano chain and cassette work so well together.”
The new technology relies heavily on the chain, so if you want the true HYPERGLIDE+ experience, you'll need a Shimano 12-speed chain to go with your 12-speed cassette. With this combination, the newly redesigned cassette smoothly guides the chain up and down the cogs, providing faster shifting in both directions. The chain itself also features an extended inner link plate that connects seamlessly with the new cassette tooth shapes, making it Shimano's most efficient drivetrain ever.
Another important component of Shimano’s 12-speed mountain bike cassette is its MICRO SPLINE freehub technology, which features a lightweight construction and works seamlessly with the new small 10-tooth cog. As the name suggests, the MICRO SPLINE design includes smaller splines that help eliminate damage and gauges from the cog on the lightweight aluminum body. There is a wide array of hub and wheel manufactures that produce components compatible with Shimano’s MICRO SPLINE and 12-speed system, meaning riders don’t have to compromise when it comes to choices.
10-51 or 10-45 Options
While most riders will likely gravitate to the wide range 10-51-tooth cassette option, Shimano also offers a 10-45-tooth, 12-speed “Rhythm Step” cassette with even tighter gear steps. This is an ideal choice for riders who spend most of their time on rolling terrain, where an ultra-low climbing gear isn't necessary. And even if your rides involve long, steep climbs, the 10-45-tooth cassette is worth considering because those tighter gear steps provide an extra measure of control on technical, rocky terrain. You can also compensate for the smaller cassette range by opting for a smaller front chainring.
“It’s worth looking at a gear calculator,” advises Murdick. “The difference between a 30/45 low gear (as in 30-tooth chainring paired with a 10-45 cassette) and a 32/51 combo is so close that most people wouldn’t even notice the difference in the easiest gear.”
Plus, if you’re not racing, you probably don’t care too much about the top end speed difference between a 30/10 and 32/10 high gear. Most of us are coasting and enjoying the descent at that point.
Constructed of lightweight and hardwearing materials, Shimano's 12-speed cassettes deliver efficiency and durability. Shimano XTR, DEORE XT, and SLX all utilize an aluminum cog carrier known as a Beam Spider while the difference between each cassette is in the cogs themselves.
XTR’s largest three cogs are made of lightweight aluminum with a special surface treatment that appears black. The middle five cogs are titanium, while the four smallest are steel. Altogether, the 10-51-tooth XTR cassette weighs in at a slim 367 grams.
Meanwhile, the DEORE XT cassette incorporates two aluminum cogs, with steel filling out the remaining ten gears. Weight for that 10-51-tooth XT cassette is 470 grams.
Finally, the new Shimano SLX cassette has one aluminum cog combined with 11 steel rings, producing a finished weight of 534 grams.
Each cassette provides a unique blend of materials and cogs, delivering the optimal combination of weight savings, rigidity, and durability for different types of riders. While weights and materials differ slightly between Shimano XTR, DEORE XT, and SLX cassettes, the unparalleled shift quality is identical.