Originally Posted by
bipedfred
The best defense is to ride a bike with zero resale value and lock it securely (as advised in these other good replies) next to the most expensive, flashy bike you can find. And even then, don't become too attached to it.
+1. Your locks don't have to be the best locks, just better deployed than the rig next to you (i.e. park next to the guy who only locked the front tire & has a quick release.)