I've seen these types of bikes at carnivals (USA, southern states, etc). I didn't try it but it was one of the few carnival games that paid out in cash. I think it was 10 to 1 odds, as in you pay 1 dollar to win 10 dollars if you can ride the bike 10 feet. without falling or touching feet. They even gave you 3 shots (probably to suck the crowd in).

No one could do it in the 20 mins that I stood by watching. Dude was making a killing. He could ride it, of course, but I wonder how long it took him working with it to master it.

Far too many years ago, when I had the joy of working front-line tech support, I once had a gentleman call in to complain the that the buttons on his mouse had the opposite functions to those described in the manual for our software. I eventually worked out that he was using the mouse reversed, with the wire coming towards him, and had always done this. He didn't think it odd that the pointer movements on the screen were opposite to his mouse movements.

Needless to say, I had to try this. As Pogo_Fuzzybutt says, it turns out that muscle memory is incredibly resilient to executive override. But then I had a bright idea - all I had to do was imagine there was a stiff bar connecting the mouse to the pointer, with a pivot in the middle. Suddenly, it was easy and I could use the mouse reversed almost as easily as normal. Unlike our trick cyclist, I could switch between this and normal mode without difficulty.

A friend of mine built one of these back in the 90's for Cyclecyde I tried it and it was just impossible but one of the folks in the group could do it just fine.

The other one that looked impossible to ride was just a little difficult, it had a additional pivot point in the body under the seat so the front and rear wheel could be as much as as 2 ft out of line with each other, I had no problem with this one but the thing would go all over the place.