How Do Bikes Stay Up?

We discussed this a while ago, I don't know the supported arguments anymore, but it turns out we were both wrong/right. It's complicated and not exactly known.

A nice quote from the brilliant physicist Freeman Dyson:

You can't possibly get a good technology going without an enormous number of failures. It's a universal rule. If you look at bicycles, there were thousands of weird models built and tried before they found the one that really worked. You could never design a bicycle theoretically. Even now, after we've been building them for 100 years, it's very difficult to understand just why a bicycle works – it's even difficult to formulate it as a mathematical problem. But just by trial and error, we found out how to do it, and the error was essential.

This is also really interesting, a bicycle that steers in reverse and is only possible to control after a lot of practice: