E thirteen external bottom bracketthreaded bbs adapt ethirteen cranks with 30mm spindle to standard bsa threaded bb shells custom seals grease fill and angular contact bearings are designed from the ground up for top notch durability and smooth spinning features cup material exa aluminium custom angular contact bearings new co molded outer seal for better protection from water intrusion improved bearing quality bsa threaded bbs fit xcx trs and lg1 cranks spindle spacers and wave washer a