I'd like to toss in another contribution to the "bike boom" equation.
Having been in the military about that time, I know that a lot of servicemen bought bikes. This was before jogging became popular (on military bases) and many servicemen saw cycling as a way to keep fit as well as transportation on the base. Many bases had some kind of restriction as to who was allowed to drive on base so the alternative was to park off base and cycle in. On one base where I was stationed, you had to be E-5 and above to get a base sticker that allowed you to park on base and E-4 to even wear civilian clothes on base. The result was that there were usually several privately owned civilian parking lots right outside the base gates and "locker clubs" on the strip where you stashed your civvies.
Also during this era, most junior servicemen were unmarried which meant they had more spendable income. You usually lived on base, so you didn't spend much for housing either. Military guys would usually try to purchase the best bikes available, either for status or just because they could afford them. For me, it wasn't until I enlisted and got a regular paycheck that I could afford one of the bikes I had been dreaming of. True, the military might have only accounted for a small percentage of bikes bought during this era, but I think if you totalled up the number of operating military bases during that period and the huge number of young men going into the service, the number of bikes sold to active duty military people would be surprising. I can remember the bike racks up at the barracks at the submarine base in New London, Connecticut and there were literally hundreds of what we then called racing bikes or English racers even if they were French made.
Fred Durrette
Summerville, SC