The BB30 standard opened up design possibilities for frames.Adapting it for Shimano cranks takes a special machined aluminum threaded bottom bracket that threads into itself.Ours are finished with CeramicSpeed Bearings.You have two choices in terms of bearings.The first choice is our low drag, long life standard bearing, with hardened-steel races and our super round CeramicSpeed Balls.The second choice is our coated bearing, which uses those same balls installed on coated, hardened-steel races for longer life and less bearing drag.