Nothing puts a stop to a good habit of commuting or running errands on a bicycle than having it stolen. If you ever leave your bike out of your sight, even for a few minutes, get in the habit of always carrying and using a bike lock. It is well worth the price and hassle to protect the greater investment you have in your bike.
There are several types of locks commonly available on the market, each with pros and cons. The information below will address the basics of each. No matter which type you choose, always be sure to lock your bike to an immovable object and try to put the lock through both the frame and the front wheel so the two cannot easily be separated from each other.
U-locks consist of a hard metal bar bent into the shape of a long U. There is a cross-bar connecting the two ends of the U (often causing it to be called a D-lock). You open the lock by unlocking with a key and swinging the straight bar away from one end of the U. There is a temptation to use this lock by just locking the wheel to the frame. Doing so may prevent the bike from being ridden away, but not from being carried off. While reasonably resistant to being cut by bolt cutters, a U-lock can be broken if there is enough room for a thief to get a jack or pry bar between the U and straight bars. Be sure the lock is sized properly for your bike to prevent it from being pried apart.
A chain lock is simply a chain with a key or combination lock connecting the ends. You can make your own from a length of chain from the hardware store, but often the available chain is soft enough to be cut with an inexpensive pair of bolt cutters. Chains designed for bicycle locks are usually made of hardened steel with link shapes designed to deter the use of bolt cutters. If the chain is long enough, you should run it around an immovable object and through the frame and both wheels. Youíll want to keep the chain short enough however, to impede the use of bolt cutters or power tools to cut through it.
Cable locks are essentially like chain locks except that they are made of cable. Most cable locks are made from spring cable that automatically coils itself when released, a feature that can make them easier to transport. A simple steel cable can be easily cut with bolt cutters. A better option is a steel-jacketed cable which is more difficult to cut. Some people will use a cable lock to secure bike components (such as the seat or wheels) in conjunction with a U-lock for total bike security.
Also called a wheel lock, the O-lock encircles the rear wheel to keep it from turning. This lock would prevent someone from riding off on your bike, but does not keep them from carrying it off.
Essentially handcuffs for your bike, cuff locks work by snapping one cuff around your bike frame and the other around a signpost, parking meter or other immovable object. This option might not be the one for you if you routinely lock your bike to trees, but it may be a good solution for city-dwellers.
No matter which lock you choose to invest in, remember that it only works if you use it Ė every time you leave your bike. Additionally, remember that all locks can be broken by a determined thief. Get in the habit of leaving your bike locked to an immovable object in a well-lit public space so that itís less likely to be targeted by a thief. Take the time to protect your investment so that it can serve you long into the future.
Ride safe and have fun!