Make your own bicycle lock.
It can be lighter, cheaper, and much more fun than any lock you can buy.
Here's one made of cardboard!
It's perfect for use in Japan and other nice places where people don't like to steal.
I live in the United States where lots of people steal things.
So we'll make a stainless steel one from an old stove.
Step 1: The Ancient U-Lock
The "Modern" U-style lock is pretty old. Here's a patent for one from 1925.
It's designed to fit over the spoked wheel of an automobile.
Back then lots of cars didn't have locks.
As Henry Ford said "You can have any color you wanted, as long as it's black."
So people accidentally taking the wrong car must have been a problem.