Shimano SM-BC06 Bell Crank Unit Description: The Shimano SM-BC06 Bell Crank Unit is a factory replacement part for a Shimano Nexus Inter3 internally geared rear hub. This unit accepts the shifter cable from the shifter on the handlebars, and inside there is a lever that actuates the pushrod in the Shimano Nexus Inter3 rear hub when a shift is made. Once the cable has been installed, the body of this mechanism has a fixing bolt that attaches this unit to the rear axle nut, and there is a clear window with an indicator to help set up the correct cable tension for optimal shifting performance. Features: Optimized for Shimano Nexus Inter3 hubs and shifters Includes cable tension adjuster to optimize shifting performance and to adjust the system as the shift cable stretches throughout its life Rear Hub, shifter, cables, and internal pushrod for rear hub sold separately