You need to think outside the box. The first lock that you use to protect your bike, no matter how cheesy, is about 90% effective because it forces the thief to have a tool to defeat it.

As you move from 90% effective toward 100%, you engage in a progressively more expensive, high tech game of one-upmanship with the thief. This is a game that you will always eventually lose because, given enough time, people have broken into bank vaults. All it takes is the right tool and, if you park repeatedly in the same place, a determined thief will figure out what he needs to bring with him.

Usually, in about the middle of summer, we get a lot of questions about buying a college campus bike. My advice is to ride a semi-expendable bike, use a 90% lock and to save your good bike for good rides.