Heavy-duty bolt cutters are definitely on that list. They’re quiet and can be effective on cable locks and thick chain. If the thief is even less discreet, you can bet there’ll be a battery-powered angle grinder in the mix too. What you lose in subtlety, you gain in speed and cutting power—in a Motorcyclist test, the toughest chain available lasted scarcely more than three minutes against a grinder. Canned air, or more specifically, the difluoroethane inside those cans, can be effective too, freezing locks and allowing a thief to bust through them with a hammer. For the clever and mechanically adept, a screwdriver, wire cutters, and a little wire are enough to make off with your machine. For other theft rings, a van is more their style because thieves can get the bike out of sight quick.