Everyone can ride a bike! Or so you thought! A simple change in the bike made it impossible for this man to ride. Moreover, it was much easier for his young son to learn to ride the bike than it was for the adult to do so.
I post this just to point out that a lot of the things we know how to do, we don't consciously know how to do. The brain, and indeed the nervous system is more complex that our conscious mind seems to understand.
Incidentally, the video is a good example of a situation in which our intuition is wildly inaccurate. He thought he could make the obvious adjustment needed to ride the bike instantaneously, and it took eight months for him to do so, at which point he could no longer ride a normal bike!