Six cogs mounted on two aluminum spiders, four loose cogs on the small end, and a construction robust enough that Shimano rates it for e-MTB use. The CS-M771 has been Shimano's workhorse 10-speed mountain cassette for years, and riders keep coming back to it because it delivers XT-level shift quality at a price point that doesn't sting when it's time for a replacement. If you're maintaining a 10-speed drivetrain—whether on a trail bike, a hardtail, or an e-bike that sees real trail miles—this is the cassette that balances durability, performance, and cost.

The two-spider design handles the six largest cogs (the ones that take the most abuse during climbing and low-speed technical work). Aluminum spiders keep weight reasonable while providing the rigidity needed for consistent cog spacing under load. The smaller four cogs are individual steel pieces that slide onto the freehub body independently. This modular construction also means you can swap in aftermarket extender cogs from companies like OneUp or Wolf Tooth if you want to push beyond the 36-tooth maximum without replacing the entire cassette.

Shimano optimized the tooth profiles for their HG-X chain and Shadow rear derailleur system, which they marketed as Dyna-Sys when 10-speed mountain drivetrains were current. The practical result is shifts that engage cleanly even when you're mashing uphill or soft-pedaling through technical terrain. The ramps and gates on each cog are positioned to catch the chain predictably, which matters when you're shifting under load and don't have the luxury of easing off the pedals.... Read More