Harvey,
I don't know the answer, but it isn't limited to Bottom
Bracket threading. Italian headsets are 25.4mm with 24 TPI
(well that one makes sense, as 25.4mm = 1 inch); and the axles
are threaded at 26 TPI, although the diameters are typically
9mm and 10 mm.
So I can supply more questions - but no answeres...
Fred Rednor - Arlington, Virginia (USA)
> Classic English, French, and Swiss threading are internally
> consistent.
> English (such as 1.370x24) is in inches and threads/inch.
> French/Swiss
> (such as 35 x1) is in mm, diameter and pitch.
>
> But Italian is different, like 36x24, meaning 36 mm diameter
> and 24
> tpi. Now I can understand the archetypal "Giacomo" doing
> this with a
> war-surplus South Bend lathe with a US lead screw and gears
> (which is
> what I learned on), but why would such a thing have become a
> national
> standard? Anyone know the history? I'm not suggesting it's
> better or
> worse, just weird. And I'm not talking about off-topic ISO
> stuff, either!
>
> This came up when I was sorting the old Campy BB cups in the
> box , so I
> could send a couple to another CR lister...
>
> Obviously there are at least three possible kinds of
> responses:
> rational, plausible, and funky-but-not-politically-incorrect.
> It might
> surprise those who know me, but I'm really most interested in
> the first
> category.
>
> harvey sachs
> mcLean va
> _______________________________________________
>
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