The National Bike Registry estimates that 1.5 million bicycles are stolen each year with a vast majority of these thefts not being reported to authorities. In fact, the FBI approximates that $350 million worth of bikes and bike parts are stolen annually. And that number is growing. Last year, for example, New York City saw a 25 percent increase in bike thefts, according to the NYPD. Even though no bike lock is unbeatable, they can still be an effective deterrent against theft.
Experts say you shouldn't think twice about investing at least 10 percent of your bike's value in a good lock or even multiple locks. There are several popular styles available, but reviews indicate that the best are U-locks or chain locks. U-locks have a thick steel shackle attached to a crossbar with a keyed lock. Chain locks have tough links typically attached with a small disc lock that requires a key to open. Both types can effectively secure your bike, but U-locks are generally lighter and more portable than chain locks.
Many cyclists use a large chain or U-lock to secure their bicycle to a stationary object, and choose smaller U-locks or cables to secure wheels and seat posts. If you live in a high-theft area, you may want to use several locks for maximum security. Urban bicyclists often select a U-lock to secure the frame and back wheel of the bike to an anchor like a lamppost and use a secondary U-lock or chain lock to secure the front wheel to the bike frame.
There are also numerous cable locks on the market, but you won't find many experts who recommend them. Cable locks use steel cables attached to a combination dial or keyed padlock. A cable lock is certainly better than no lock at all, but they can be broken in seconds and provide little security in high-theft areas. Still, they can be a decent secondary option when used with a tougher chain or U-lock.
In general, U-locks are believed to provide the best protection against bike theft, but even these locks aren't perfect. Gadget website Gizmodo.com tests four popular locks against easily accessible tools such as a bolt cutter, hacksaw and inexpensive angle grinder. While the locks hold up against the bolt cutter and hacksaw, all give way to the angle grinder in less than two minutes.
In the comparative reviews of bike locks we found, several are outdated or focus on internationally available models, but all reviewers tend to consider the same criteria. While the best bike locks are easy to use, they can be heavy; weight often corresponds with the security a lock offers. Consumers should look for locks made with tough materials capable of weathering the elements. Hardened steel, weatherproof protectants and a protective rubber coating are all big benefits.
The best bike locks perform well in actual security tests but will be light enough to transport or come with an easy-to-use mounting bracket. They should also include a strong manufacturer's anti-theft protection plan. Many industry leaders offer warranties that cover up to a stated dollar amount in bicycle theft cases. These plans can be time-consuming to enroll in and require some paperwork, but it can be well worth it in the long run.
The best expert bike lock reviews can be found at Wired and Men's Journal. We also found helpful comments at BikeRadar.com, where contributors test locks for strength and durability but don't compare them to others on the market. Owner posts are also valuable, especially at Amazon.com; many bike locks attract at least a dozen comments. Other review sites such as Buzzillions.com and TotalBike.com offer some feedback but are far from comprehensive.