M12 pitch 1.25 for use on factory or external wheels with a 60 degree tapered seat wheel for 4-hole hubs and alphalomé wheels. The length of the neck should be measured not only the thread but also the tapering surface of the neck should measure a few millimeters (2 millimeters) (If you measure the original bolt yourself and get a 0.8 inch (21 mm), please try to measure it from the end of the tapered seat.)