I'm pretty sure they'd laugh, and if they were alive today they'd mostly be hanging with the crowd we see constantly pushing the boundaries of cycling technology. Technology that many of us here in C&V refuse to tamper with, if not outright reject.
If you consider only those that were using every advantage to break a record or win a race, you are probably right - they'd be amused with us. But if you look at the larger population of cyclists of the fifties, those who reveled in the basic magic of the bicycle - how a simple machine can parlay the energy of a brisk walk into a exhilarating sensation of speed - those blokes might be heard saying "disc brakes, brifters, who needs 'em?".