Cassettes aren’t sexy. Unless they’re XTR. We didn’t think there was much left to do with cogs, but then Shimano went out and re-designed this cassette, with reprofiled, stiffer titanium sprockets in the four largest cogs. This means they’re lighter and shift better and there’s less energy loss. The five steel cogs have also been reprofiled for better shifting, with the two largest steel cogs mounted on an alloy carrier for further weight reduction. The alloy carriers are also nice from a mechanic’s standpoint, as they’re faster to get on and off the cassette body and are not going to notch the body, which makes removal and assembly a pain. The carriers also make de-gunking easier and faster.

The Shimano CS-M970 XTR Cassette comes in three configurations, nine-speed 11-32t, 11-34, and 12-34. The four largest cogs are made of titanium and are mounted on alloy carriers, two to a carrier. The carriers are re-designed to be lighter and stiffer. The five steel cogs are in two groups, the two largest of the steel cogs are mounted on a single alloy carrier. The three smallest are “loose,” not mounted to carriers and slid on to the cassette individually with spacers separating them. The steel sprockets are finished in nickel. Shimano recommends using their Super Narrow HG chain with this cassette. 224g. MSRP $239.99.