The uninterrupted shifting experience of the Shimano Ultegra CS-R8100 12-speed cassette range lets you climb, sprint, or cruise without stopping to think about your next gear change. Larger driving cogs maximize drivetrain efficiency and create compatibility with both Shimano 11 and 12-speed freehub bodies. Shimano HYPERGLIDE technology is integrated to provide seamless shifts both up and down the gear range. -Refined 12 step gear combination provides peak efficiency and accelerating performance for every racing situation -Faster, smoother shifts under maximum pedaling force -Compatible with 12-speed and road 11-speed freehub body