The Shimano Ultegra CS-R8101 12-Speed Cassette ensures a smooth, uninterrupted shifting experience, whether you're climbing, sprinting, or cruising. Its larger driving cogs enhance drivetrain efficiency and offer compatibility with both Shimano 11 and 12-speed freehub bodies. Thanks to Shimano's HYPERGLIDE+ technology, you can expect seamless shifts across the entire gear range, whether shifting up or down. The refined 12-speed gear combination optimizes performance for peak efficiency and acceleration in every race scenario. It delivers faster, smoother shifts, even under maximum pedaling force.