This International Standard specifies the thread profile and limits and tolerances for the screw threads used to assemble freewheels on bicycle hubs. It is based on a) the use of the ISO basic thread profile given in ISO 68; b) satisfactory interchangeability with the corresponding British Standard Cycle (B.S.C.) thread; this has required the use of an inch pitch (t.p.i.); c) the use of screw thread tolerance grades and tolerance positions given in ISO 965-1 ; d) the use of gauges made to ISO 1502.