I'd factor in huge improvements in road surfaces. I've had guys INSIST my PX-10 is a "touring" geometry and not racing! That shows you how angles, top tube lengths and fork rakes have changed as road surfaces have improved. How many modern cyclists even know why racing cyclists wore goggles up to about the mid 1950s?
There's also a big difference in standard of living and the now widespread use of cars. How many modern cyclists can conceive of the once common British practice of cycling say 50 miles in predawn darkness to a race or time trail, compete in that and cycle 50 miles home in darkness? Very often on wired-on tyres and with sprint wheels bolted to the outside of the forks? Folks didn't have cars like they do now. You rode to a race. And back. It's the sissy factor of modern cycling that also permits specialisation of frame types that most simply couldn't afford 60 years ago. The "All Rounder" cycle has all but vanished as a result.
But a fascinating subject. And a challenging one to we preservationists. Do we strive to RIDE a specific era machine as it was intended or do we fight it and insist "I can't ride that, I need wider 'bars etc."? To me, it's half the fun of collecting and RIDING different era machines. But I still don't really have an old enough racing bike to warrent wearing cycling goggles. That's incentive enough to add one to the collection!
Peter Kohler
Washington DC USA