Originally Posted by Road Fan

I tried to estimate your frame angles by measuring your photos with a protractor. The only thing I can say with confidence is that your seat tube angle is on the shallow side, like my 1952 Rudge sport bike, which has been pictured on this site. Your head tube is much steeper than mine. I don't believe the numbers I got, which were 70 degrees rear and 75 degrees front - not obviously wrong but certainly not typical (maybe except for Doug's Ukrainian project bikes?). My Rudge angles from 1952 measure (measuring the frame) 70 degrees rear and 73 degrees front, which I believe but still not measured with an accurate process and toolset. The Rudge's trail is about 40 mm, so I think its 73 degrees is reasonable. In the past I've done some such scaling from the pictures in Jan Heine's books, but in those the photographer specifically tried to minimize angle errors. My numbers were pretty close to what Jan claimed, but I don't think that proves anything.

To the Thread Starter: I'm envious at you having a Cyclery North bike! I'd love to find a 52 cm-sized version of that Hellenic design!

Kind of a final note: If my estimates of your frame's geometry are accurate, I think you have an odd bird there which might have iconoclastic handling. It would likely be different again if you convert it to 650b. Presumably the original builder had a sound idea of how the bike would handle and for whom, and that the bike would be an acceptable ride as he designed it either with 27" or 700x25 tires. I think I would build the bike today to follow the original geometry (adapting to my own fit) before thinking seriously about anything more radical, like a 650b conversion.