bike locking strategy

by sheldon brown

If you don't have secure parking at your workplace, you should indeed have a serious lock, such as a Kryptonite. The thing is, you should not carry it home every night. The weight of a typical U-lock represents the difference between a $400 bike and a $700 bike.
Just leave the lock at work, locked to whatever you normally lock your bike to. Carry a light cable lock with you for quick errands or emergencies.

If you use both the U-lock and the cable lock at work, you are more than twice as safe as you would be with either of them alone. Either type of lock can be defeated, but each requires a different large, bulky tool which is useless against the other.

Don't take your bike apart to lock it, it is really bogus. The cable lock will secure your front wheel to the frame and any convenient object, and the U-lock will secure your rear wheel and frame. If you have a quick-release seatpost bolt, replace it with an Allen head bolt, and stop worrying about having your saddle stolen.

The best cable locks are the ones that have the lock built-in, rather than relying on a padlock. The padlock is the weak link, easily cut with bolt cutters, the tool of choice for most bike thieves. A new, sharp bolt cutter will cut a cable too, but an old, worn-out one will only crush a cable.

The best U-locks are the smallest. My favorite is the Kryptonite Mini, which not all bike shops stock. The Mini is much smaller and lighter than the more popular models, but just as secure. It may be even more secure, because of the limited room to put a jack inside it. It also gives less purchase for leverage-based attacks.
People tend to buy the big clunky U-locks because they don't know how to use them properly. A U-lock should go around the rear rim and tire, somewhere inside the rear triangle of the frame. There is no need to loop it around the seat tube as well, because the wheel cannot be pulled through the rear triangle.

Some will object that felons might cut the rear rim and tire to remove the lock. Believe me, this just doesn't happen in the real world. First, this would be a lot of work to steal a frame without a useable rear wheel, the most expensive part of a bike, after the frame. Second, cutting the rear rim is much harder than you might think. Since the rim is under substantial compression due to the tension on the spokes, it would pinch a hacksaw blade tight as soon as it cut partway through. Then there are the wire beads of the tire, also difficult to cut.