Originally Posted by Beez
I don't see a downtube on the bike?
Could someone point it out o me?
On closer scrutiny... the black tube I mistakenly took (at first glance) to be a frame downtube... may well be a radiator hose.
(behind the radiator - from rear 3/4 view in the middle photo).
I did say it was an "armchair observation" - after all...
As Brodovitch's reference earlier... the B/F frame could well be similar to the Speedbrain design.