Titanium, aluminum, steel, and carbon fiber each handle different jobs across the CS-M9001's eleven cogs. Shimano built the XTR cassette this way because each material excels where the cassette needs it most. The four smallest cogs take the heaviest chain load during high-speed efforts, so they're nickel-plated steel for durability. The middle six cogs see moderate stress and benefit from titanium's strength-to-weight ratio. The 40-tooth climbing cog uses aluminum because it's the largest and experiences the lowest chain tension, making weight savings most effective there. Carbon fiber spider arms tie everything together while keeping the total package at 331 grams.

Rhythm Step gear progression defines how the cogs are spaced, and this matters more than raw tooth counts suggest. The 11-13-15-17-19-21-24-27-31-35-40 arrangement keeps cadence changes consistent from one shift to the next. At typical pedaling speeds, each shift produces roughly a 10 RPM cadence change regardless of where you are in the cassette. That consistency prevents the jarring leg-spin changes that happen when gear steps vary widely, which is especially noticeable during technical climbs where maintaining momentum requires smooth power delivery.

The HG-X11 tooth profile shapes each cog specifically for 11-speed chain engagement. Ramping and pickup points on the teeth guide the chain during shifts, which reduces noise and hesitation during gear changes. This profile requires a Shimano 11-speed chain to work correctly. The HG-X11 or HG-901 chains are the recommended matches, and using a different chain will compromise shift quality and accelerate wear on both components.... Read More