Master lock makes only three grades of locks: crummy, really crummy, and really, really crummy.

Don't look at a lock unless it has received a "top" rating from "Cycling Plus" or from Soldsecure. The best (and most expensive, and most heavy) locks from both Kryptonite and OnGuard rank at the top of test after test. The locks from Master finish last, in test after test.

If your bike is worth more than $200 or so, (and looks like it), you probably need two locks. Put a heavy duty lock, such as the Kryptonite Fahgettaboudit u-lock around your rear wheel and a beefy locking post that is set in concrete. Use a lighter lock, such as the Kryptonite Evolution Mini u-lock to attach your front wheel to the frame.

In test results, the chains that weigh eight or ten pounds do NOT perform better than u-locks that weigh five or six pounds. So, the only valid reason to use a chain lock is that you park in a neigborhood where there are no locking posts that fit a u-lock. If you MUST lock to streetlight poles and powerline poles, obviously, you are stuck using a chain lock.

And, if your bike is worth more than $500 or so (and looks like it) I would not park it out of your sight for more than five minutes with ANY lock. No lock will stop a crook who has the right tools and know-how, and an expensive looking bike, left unwatched for six or eight hours is eventually going to catch the eye of exactly that sort of crook.

And, talk with your insurance guy. Make sure your bike is covered by your renter's insurance or your homeower's insurance, and that the deductible is reasonable (No point having a $500 deductible on a $500 bike).