Steven Maasland wrote:
622 has long been the 'standard' size for all tubular tires. It therefore was the default size for all framebuilders of 'racing' bikes where tubulars would be chosen. All of continental Europe used this as the 'racing' standard. For city bikes, there were both larger and smaller sizes used.
The 27" (630) size was mainly a British standard, and therefore by default, in many other countries where the British bike industry held sway. I believe it was the arrival of the high quality clincher tires and rims that brought about the decline of the 630 size as more and more 'racers' decided to go with clinchers on their high-end frames built around the tubular standard.
==================== Granted that Houston was (and remains? :_)) a backwater in cycling, I first saw 700c, as opposed to 27" wired-on tires about 1965 or 1966, and felt that they would not catch on in the US.
But, it didn't take long to realize that 700c allowed me to interchange racing sew=ups with training wired-on (Fred Kuhn at Kopp's Cycles, Princeton, would never tolerate the term "clincher"), without any change in brake set-up. Not perfect, but you could get away with it, and you couldn't with 27". I suspect the racers and wannabes were pretty significant in getting feedback to the shops about this advantage, but may overestimate our importance. In any event, this was years before I was able to find small cross-section tires in either 700c or 27".
Harvey Sachs
McLean VA