Shimano Alfine SG-S7001-11 Clutch Unit Description: The Shimano Alfine SG-S7001-11 Clutch Unit is part of the driving mechanism within the internal assembly of the Shimano Alfine 11-speed internally geared rear hub. If the rear hub is slipping or not engaging when pedaling the bike forward, then this part will restore the functionality of the rear hub if it is installed when performing the maintenance of the rear hub. Features: Includes just the clutch unit Hub Axle Unit, Return Spring, and other components of the internal assembly sold separately