This International Standard specifies details of the screw threads used to assemble head races and locknuts, i.e. fittings, on bicycle fork steering columns. The basic thread profile is that of ISO 68; the tolerance grades and tolerance positions are in accordance with ISO 965/1 ; the gauging system is that specified in ISO 1502. Threads to this International Standard are interchangeable with the corresponding BSC (British Standard Cycle) thread.