Hope pf41 press fit ceramic bottom bracketour press fit bottom brackets feature high quality sealed cartridge bearings providing a solution to the press fit bottom bracket minefield features 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 ceramic cartridge bearings ability to convert the bottom bracket to fit truvativ gxp cranks with a simple shim adaptor specific fitting tool required