The Alfine 8 speed internal gear hub runs on needle bearings for increased durability & high drive efficiency Top normal internal structure for enhanced tolerance when shifting while riding under load Labyrinth seals improve sealing performance extending service life Alfine hubs use pedal power to aid down-shifting resulting in fast & accurate shifts with an exceptionally light feel Double roller clutch engagement also gives a smoother quieter shift Shimano's precise manufacturing abilities have enabled them to construct the Alfine internal hub to be there most efficient yet Centre-Lock disc rotor compatible 135 mm O.L.D. spacing Average weight 1680 grams