If i have a bike lock, can i trust it won't be stolen?

my last bike I didn't have a bike lock and it was stolen (it was behind a store in a place in the middle of no where so I didn't think somebody would steal)

well maybe I should just steal a bike myself then =P

No, you cannot. If you leave your bike, and it is nice enough in a high-theft area, chances are it will be stolen. You can reduce your chances by leaving your bike unattended for shorter periods of time during daylight hours in well-populated areas or by buying a beefier lock, but if you leave it out overnight, someone can come by and clip it off no matter how large the lock.

a chain bike lock can be sawed through quickly and easily with a hacksaw, however, this does not nullify the lock's usefulness. A lock will work if the bike is placed in public view where a thief will have to worry about being seen while attempting to saw through the lock to steal the bike. Lock your bike up someplace where many people pass by and no one will dare attempt to steal it for fear of being seen. Thieves are not scared of locks they are scared of people.

Where I live in NC, 3 locked bikes have been stolen from the rack in front of the police department this year. Several old junkers were stolen from the local bike collective, the cable they cut was worth more than the bikes - not to mention they could have had them free with help making them rideable if they had asked. Idiots are out there.

No guarantees. Any lock can be broken if someone wants your bike bad enough.

Locks, in general, will encourage a casual thief to look for a bike that isn't locked. On the other hand, a lock may annoy them enough that they'll vandalize it and leave.

A pro will have a bolt cutter.

People could always cut the lock if they wanted, but chances are not as great as when you put your bike out without a lock.

It helps but there is never a guarantee, if people want it they will take it, thats the sad reality of life.

if someone really wants it they will steal it, just look at how many cars that have the best alarms get stolen!