I rode one once. I rode it less than a block, just to try it. I was working at the bike shop in Tenafly, NJ. I found it was amazingly easy to get up on. Also, the giant wheel makes a giant gyroscopic force, so the bike loves to stay up. I felt no danger of falling over.

Except, of course, that most of my weight was just behind the front axle. The reason these are dangerous is that if you decelerate too quickly, you go over the front.

Also annoying was the front wheel's tendency to go left and right as I pedaled, which sucks a lot of energy.

I rode to the end of the block and came to the intersection with a highway. I suddenly realized I didn't know how to get off. I didn't feel coordinated enough to step backwards on the step, so I spilled the bike deliberately. I didn't get hurt, but that's one maneuver that I would need to practice.

That was back in 1984. I recently went back to that shop after many years. It has a new owner. The ordinary is still sitting out in front of the shop, and it's now too decrepit to ride. Much too dangerous, without some major work. Too bad. My former boss occasionally rode it between Tenafly and Closter, about four miles each way.