Doug Miller writes:

Reminds me of a friend who thought we would fly on bicycles some day,
it was just a matter of improving the mechanical efficiency. That he
couldn't run up a few flights of stairs without being exhausted
didn't seem to be a problem.

There *have* been a few flights of such aircraft already, you know.

Lean athletes in an agony of exertion pedaled around a track in a fragile
contraption. I suppose you too believe this will be perfected into a
flying bicycle for grandma someday?