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
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.
Step 2: Boston Massachusetts, 1974
That's because North Korean submarines loaded with ninja spies go there to steal bicycles.
There are about fifty colleges within ten miles of each other. All those students are
1) Easy to steal bikes from, and
2) Easy to sell stolen bikes to.
When I lived in Boston I had the lock made from these patent drawings. It was great. It was a bit unusual, so the North Korean training camps didn't bother teaching people how to break them open.
This excellent but simple lock is the inspiration for this whole project. The drawings shown here explain all you need to know about how it works. To keep boltcutters from reaching the hasp of the padlock, there is a sort of box around the padlock. The crossbar has lumps to keep it from pulling through the U.