Halo spin doctor disc rear huball purpose mtb sealed bearing rear cassette disc hub light enough for cross country rigid enough for freeride buff enough for dh the spin doctor rear disc hub uses a bolt on 2 bearing cassette body with an integrated 3 pawl positive engagement drive this places the 2 main hub sealed bearings on the outside of the hub beyond the cassette body providing superior axle support the outboard bearing construction reduces axle flex and thus reduces bearing wear