Shimano's experience in forging, machining, and engineering allows for an enormous amount of technology that goes into tooth design, shaping, and shifting ramps. The cogs themselves are constructed from a nickel-plated steel that prevents corrosion and is Read more.
The top five cogs are grouped as three and two, respectively, and are riveted to anodized aluminum spiders that add stiffness to improve shifting. The remaining six cogs are individual with spacers between, and an anodized aluminum lockring screws into the freehub to hold the entire assembly together. One spline of the cassette is wider than the others and corresponds with the splines on the freehub, so the cassette cogs can only be installed with the right clocking of the shifting ramps, timing them for perfect chain pick-up and release. This innovation is true to Shimano's Japanese culture, which uses the term "poka-yoke" to refer to features—like these guiding splines—that serve as built-in wards against user error.
