The Alfine 11-speed internal gear hub runs on needle bearings for increased durability & high drive efficiency Helical internal sprockets increase durability perform better with high torque loading & provide a constant engagement for a smooth & quiet operation Oil bath lubrication system increases durability & reduces friction in the hub while Labyrinth seals improve sealing performance both resulting in extending service life Silent clutch engagement also gives a smoother quieter shift Shimanos precise manufacturing abilities have enabled them to construct the Alfine 11-speed internal hub to be there most efficient yet Centre-Lock disc rotor compatible 135 mm O.L.D. spacing