Snip: > Nakasawa and San Rensho are probably the only recognizable/credible/winning racing bikes
Ahmmm: In the 70's there were plenty of really good bike shops and builders in Japan Japan in the 70's had 80 million people, they could easily absorb all high-end and custom production ... just because it didn't get to the U.S. does not mean it didn't exist. There were many great builders then as now who could demand and get much more than the U.S. market could bare. Most of the good builders could, then and now, make a very respectable living making custom track bikes,locally, for professional Keirin racers. Those bikes were and are every bit as good as anything produced in the U.S. or Europe.
I can vouch for the hardiness and liveliness of Keirin bikes having ridden (illegaly) a cast-off Miyata in the hills of Hakone National Park. The Miyata was nowhere near as pretty as my old Scwhinn Paramount track bike, but every bit as good (my knees ache thinking about both of them).
Amir Avitzur
Ramat-Gan, Israel