Originally Posted by
unworthy1
Hmmm, those seat post sizes, if correct fit, point to something with "heavier walls" than regular 531 "C" and could be Tange or Ishiwata as you surmised. Which makes this being a "custom" more likely, some builder who mixed tubing, used some Asian-sourced frame bits as well as Euro, kind of more the "American" practice than British. Then you've got the metric pinch bolt and 27" wheels (but this is not a "touring" frame from the look, despite one set of eyelets). Strange bird, indeed!
Strange is the perfect word. Very unique.
Also, this is set up for nutted brakes, reinforcing the 1979 build year theory.
I agree, from what I know about seatpost sizing combined with Reynolds steerer and possibly forks as well, this is likely a handmade custom order from an American frame builder. I need to nail down that serial format though. Unfamiliar with it.
Thanks all for the input. Will continue to do my own research as well. 👍🏾