Re: Continental by the inches
I've seen films of the Schwinn electro forging process. Those text descriptions are certainly lacking. The parts are more slammed together in a huge shower of sparks. But slammed in a controlled way. The amount of material sacrificed is carefully calculated and measured for in advance. There is no second chance. mess it up and toss the frame.
Every bike company measures frame sizes in their own way. Schwinn listed their 70's varsity & conti models in even inch sizes. 20 22 24, etc.
Some companies measure:
center to center (center of the intersection of the seat tube & top tube)
center to top of seat tube (rather meaningless to include the separate clamp area)
center to top of top tube (center of the seat tube in line with the top of the top tube)
and with modern bikes with sloping top tubes you can measure "Virtual" seat tube lengths, ie, where the top tube would be if it were horizontal to the ground starting at the head tube.
At least they all measure from the center of the bb shell at the lower end.
More useful these days is "Stand over height". From the ground to the top of the top tube, half way from the head tube to the seat tube. It's been commonly accepted that a rider should be able to stand over the bike, both feet flat on the ground for ease of mounting, dismounting and general control. Buying a bike for a kid that they "will grow into" is frowned upon. Back, say 100 years, most bikes were rather large and people were shorter. There was no stand over clearance. But there weren't red lights or many stop signs to deal with either. And there was no futzing with toe clips or cleats.