Press fit pf41 bottom bracket 86589592 pf bottom brackets are designed to fit bikes with a threadless bottom bracket cup the bearing cups thread into a centre tube to give a very secure safe fit 24mm axle version only stainless steel cartridge bearings ability to convert the bottom bracket to fit truvativ gxp cranks with a simple shim adaptor specific fitting tool required purchased seperately for 24mm crank axle cups pressed in and held in place by a screw in centre tube to prevent sli