(I posted this in another thread, but I thought I would start a new one for all of those people who will search it out in the future. Please ask any questions on locks, methods, lubrication, and/or maintenance that you may have)
Okay, I see one of these lock threads pop up every couple of weeks here.
I am a CRL (certified registered locksmith) in Illinois. Have been for about 14 years.
I have dealt with many customers' questions after they just lost their bike to some thief. I know exactly which methods are used by thieves, and exactly which methods will actually work best on most, if not all of the locks out there.
Here are some thoughts:
You should lock your bike in accordance with:
1) Your risk of theft (crime rate in your area, or your personal paranoia)
2) Your available budget on a locking system.
3) The value of your bicycle.
4) The length of time you will be leaving your bike locked.
*Not necessarily in that order*
MOST bike thefts ARE a crime of opportunity. Committed by low level thieves who carry around bolt cutters, pry bars, and/or a small jack.
**You CAN defend your bike against this type of theft with a locking system.**
SOME (very few, at least to my knowledge, in chicago) bike thefts are committed by individuals who specialize in this kind of work, have the skill, speed, tools, and know-how to steal bikes very quickly. They usually carry a variety of tools in a van and can steal, pretty much any bike they want.
**You CANNOT prevent this type of theft with ANY locking system that I have seen**
Thieves do not pick locks, they break them.
A cordless angle grinder with the right blade can and will cut through any LOCK/CABLE/CHAIN that I have seen on the market. This can be done in under five minutes per lock/cable.
So, you can't stop someone with a grinder, you can only slow them down by using multiple locks.
The best way to lock your bike for MAXIMUM security is to use this cable with this lock (links below), looping one end of the cable through your front and back wheels, around the frame, and around whatever you are locking to. Lock both ends of the cable with the padlock. They will barely fit into the shackle, but they will fit. Even more easily if you cut away the plastic covering in one small section of the eyelets to help with this.
**EDIT: I now recommend MEDECO padlocks (and lock systems) due to some shop defeat research I have done on the MULTI-LOCK brand. They are more easily drilled out than the MEDECO due to better construction and more hardened material in the MEDECO cylinders.
Then use one or more kryptonite U locks (the best you can afford) to lock the frame and/or wheels in addition to the above lock. This is deterrence. Even hearty bike thieves will move on to another 'easier' target when they see this. The more locks that they have to break or cut through, even with a fast grinder, the better. Opportunistic thieves won't even look twice before moving on.
Multi lock (and MEDECO) brand locks MUST be purchased through a locksmith. The keyways are restricted to individual lockshops and, therefore, cannot be duplicated, even by another multi lock/MEDECO dealing locksmith. When you purchase a lock and keys, the key bitting(s) will be recorded by the locksmith onto a key authorization form. The only people that will ever be able to get keys to your lock will be the people named on this list. Period. You will have to return to that same lockshop, with a valid photo ID, to obtain replacement/extra keys (very handy if you lose your keys).
The lock cylinders are virtually pick, drill, and 'bump' proof. (Moreso in the MEDECO)
Unless you are in a very low risk area, DO NOT use combination cable locks. They are too easy to open if you know how, and it is not hard to find out.
Don't lock your bike in dark, low traffic areas, or parking garages, if it can be avoided.
With all of that being said, I use the above cable locking method, but with a kryptonite U lock EVERY time I lock my bike. I will use a secondary kryptonite U lock on the frame if I will be locking it for an extended period of time.
Kryptonite brand is highly recommended, especially their higher end products.
I hate bike thieves.
You can't stop them all, but you can stop 90% of them if you just invest a little money and lock your bike properly every time.
Edited 5-10-10 with new information.