A thief with enough time and the right tools can break any lock. But you can discourage thieves if you follow these tips about your bike

To prevent your bike from becoming a statistic lock your bike to a fixed object whenever it's left unattended.  If possible take your bike with you wherever you go.

Security: Lock your bike to something that's permanent and not easy for a thief to take. Lock to a bike rack, a parking meter, a metal fence, a street sign or a big tree.

Visibility: Park where many people pass by and where they can see your bike easily. Thieves don't like an audience.

Close By: Put your bike where you can get to it fast. Thieves like to steal bikes whose owners are far away.

Cross Locking: A good way to foil thieves is to use more than one kind of lock. For example, put a U-lock through your frame and rear tire, and put a cable or chain through your frame and front tire.

Placing the Lock: Some thieves can break a lock by putting it against a wall or sidewalk and smashing it with a hammer. If you use a padlock, try to put it where it's not close to the ground or against a wall or another solid surface.

Don't leave loose accessories on you bike unattended such as pumps, lights, computers or equipment bags.  Remove them from the bike and take them with you.