The Shimano Ultegra 12-speed hyperglide+ racecassette is designed for supple switching while climbing, sprinting and enjoying bike rides. With larger drive wheels, the drive is more efficient and suitable for both Shimano 11 and 12-speed freewheel hubs. The revolutionary off-road switching system of hyperglide+ cassettes ensures seamless switching throughout the range. Even with maximum effort you don't have to take back to switch. With the Shimano Ultegra R8150 drives you achieve maximum efficiency in every gear. The Ultegra CS-R8100 Cassette now offers 12 gears and is the new benchmark for switching on the road. Product specifications-Model: CS-R8100-12-Series: Ultegra R8100 Series-Average weight: 291 (11-30t) 345 (11-34T)-Combination: 11-12-13-14-15-16-17-19-21-24-27-30t | 11-12-13-14-15-17-19-21-24-27-30-34T-Combination name (group name): 11-30t 11-34T-Type: Hyperglide +-Compatible chain: HG 12-speed-Rear: 12-Aluminium leaf_cademic (st.): Splinium spinium spiny. (Road 12 -speed dedicated): yes - steel leaf_e: 12 - titanium leaf_: 0): 0