Boost CL R 32H 148x12 XD Gold Steel Bearing for BOOST Center Lock Rotor Mount Rear Hub Mountain Bike BOOST Rear Hub Boost Centerlock Rear Hub is a staple hub for mountain bikes such as Enduro, trail bikes and more. The 72 Notch Ringdrive Ratchet System is still the best balance of ChrisKing hub products over a quarter of a century since its launch. The structure is easy to see at first glance with a few parts boasting reliable torque transfer and less friction loss, and now the unique "Bee sound" ratchet sound shows off the identity of ChrisKing Boost Centerlock Rear Hub features tension spring inside the cassette body for all cassette types. Provides proper pre-load bearing for stable and smooth rotation. Regularly pour love (i.e. cleaning and grease up). The easy to maintain, ChrisKing hub will keep you spinning at its best for an incredible long time