U-locks + levers or grinders take time to break, at least. A cable can be cut in literally seconds. Yes, smaller U’s are better, but again– thieves are looking for easy, and would rather pass up any U-lock for any cable lock.

The bic pen trick has not been a problem since 2006. They corrected that years ago, so any new U-lock is not a problem.

This is why we can’t have nice things, Bjorn.

So U locks have issues too. They are vulnerable to lever attacks. Way back in the 80′s folks would add iron plumbing tees and ells to beef up the locks. Then this famous lock picker figures out that a Bic pen can open ‘em up 123. Also a car jack will pop them open pretty fast

I suggest the baby U lock as being harder to lever but that leaves you with the problem of securing both wheels and getting the baby lock around something stationary.

I’ve seen some pretty stout square link chain that looks promising. Also twist links help against a cutter attack. The thing with chain is it can be cut. Bolt cutters don’t work well, but there’s a shear that is set on the ground then struck with a hammer.

Then there are die grinders and angle grinders. Nothing will stop those.

I suggest beaters for daily riders, keep the nice bike indoors (although lock it there too), and get some insurance.