>
> > I still do not know the "1" at thread size stand
> > for, maybe 1 inch=25.4mm?
>
> It means "one thread per millimeter".
Close - it means "one millimeter per thread" Unlike the Inch system, where a larger number means a finer thread, in metric a larger number means coarser. 8 x 1.25 is seen on a lot of stem and seatpost bolts; 5 x 0.8 is the common thread of toe clip and fender bolts
Mark Bulgier
Seattle, Wa
USA