Kurt, No need to worry about being off topic - my 1978 Raleigh Pro frameset (1st year non-fastback seat stays) had a Whitworth seat lug clamp allen head bolt.
Eric Elman Somers, CT OT - My 1959 Morgan +4 is almost all whitworth threads.
> Whitworth threading is perhaps the best threadform from a mechanical
engineering standpoint. I haven't seen it on bicycles before but it is
commonly found on British cars and motorcycles from the '50s and '60s.
>
> The threadform has nicely raduised roots and crowns and thus avoids stress
risers. In fact at least one F1 auto racing engine STILL uses Whitworth
threadforms for the connecting rod and main bearing caps as they've been
found to be more reliable! Hope this hasn't gotten too too OT. I DID say
'50s and '60s!
>
> Kurt "ain't stripped yet" Sperry
> Bellingham WA