Had a single bike stolen once but that one was locked with a ringlock (as is usual around here) and a 1cm thick steel cable.
I wasn't the only one because there were many cut off locks that day. Anyway, my bike insurance paid me the whole amount and I got myself a new bike with a much sturdier Abus motorcycle chain lock.
I don't understand American cyclists and their insistence on U-locks. Those things are very impractical around here.
Can you provide a picture of what is more common where you are from? Just wondering.
Pretty much any bike that gets used for transportation has a
ringlock in combination with a
chain lock.
Here is my bike for example:

That's a 120 cm (I think) long 1cm thick hardened metal chain around the seat post and a ring lock on the rear.
Yeah, like a track bike but with thicker touring type tires... or as it was called back then a grampa bike, as generally you used to only see old men riding them.
Why U-locks? Because you can't cut them generally with a easy to conceal small bolt cutters like you can cable or chains. Whenever I see cut locks, its usually cables or chains. Seeing cut u-lock is pretty rare. I can't see how they are impractical? It's pretty rare when I find myself someplace where there is nothing I can fit one around to lock my bike to.
I get what you are saying. But keep in mind that a $20 5 mm shackle chain is no comparison to a $60 13 mm U-lock. Cables are even worse in that regard. That was the only time a bike of mine got stolen.
Because a chain gives you
much more flexibility in regards to locking options at a slight weight penalty.
(But let's be honest here. If 500 grams of extra weight on a bike bothers someone, they either need to get some more muscles or lose some weight.

)
It is quite easy to carry a 120+ cm long chain but it looks ridiculous and is impractical/impossible to carry a 60 cm long (~2 foot long) U-lock
For example; Let's say I want to lock my frame to a lightpost but also want to prevent my front wheel from being taken?
No problem with a chain but very tricky in most cases with a U-lock.
