The purpose of using a bike lock is to help prevent bike theft. A bike can be locked to an external support (like a light pole or bike rack), to other bikes, or, to some degree, to itself. This is particularly true if you’re trying to protect certain components from being stolen—for instance, by using a cable or U-lock to lock a tire to the bike frame to prevent the tire from being removed. "The most effective way to lock a bike is to lock parts of your bike according to value. The biggest priority here is making sure your frame is locked to an immovable object. Then, if you can lock other parts of your bike (wheels, saddle, or handlebars), go for it,” says Taylor.