This was discussed long ago in the "old" rendezvous, the legacy of TPI stems from the retooling of post WW2 europe with machine tools made in the USA. Even tho it was possible to turn parts to metric diameters, the lead screws on lathes kept much of the bicycle industry locked into english pitch when threading parts.
Mark "nothing wrong with 55 degrees" Petry
> I think all English and Italian thread dimensions, at least back to the
60's and
> perhaps much earlier, always expressed the thread pitch in TPI. French
and Swiss
> thread pitch, so far as I know, were always expressed in mm. I doesn't
seem to
> matter who the manufacturer was, only which threading standard the
component
> used. I don't know how or when the Italians came to use a hybrid spec
including
> TPI.
>
> Regards,
>
> Jerry Moos
>
> Wdgadd@aol.com wrote:
>
> > I've been wondering how this odd mixed system evolved. The diameter
is a
> > metric dimension (9 or 10 mm) yet the number of pitches is in a now
obsolete
> > British dimension (British Standard Cycle). I know Zeus used this
system; did
> > other non-Japanese Campy clones? Do current Campy hubs still use this,
or
> > have they standardized to a straight metric/ISO for axles and cones?
> >
> > Regards,
> > Wes Gadd