Rotor pf46 bbright steel bottom bracketrotors press fit bottom bracket bearings are compatible with all bb90 press fit system frames that are manufactured to shimano specifications the new advanced non contact labirynth seals yield a buttery smooth spin with unparalleled protection against dust water and mud ultra rigid plastic caps give high compression and deformation resistance facilitating crisp shifting featuresfor use with bbright 46mm systems to convert down to 24mm axle systems t