EmailYou can usually get a good sense of how well a lock will prevent theft by the manufacturer's anti-theft protection plan, if they offer one. Kryptonite offers a $4,500 anti-theft protection plan for their top-of-the-line U-lock, the New York Fahgettaboudit. A smaller Kryptonite U-lock, the Evolution Mini, only comes with a $2,000 protection plan. Keep in mind that in order to take advantage of the anti-theft plan, you will need to send a number of documents to Kryptonite within 15 days of purchase; you will also need to send in pieces of the lock as "proof of lock failure" if your bike is stolen. If the thief doesn't leave lock remnants behind, you may be out of luck. OnGuard also offers anti-theft protection plans for some of their bike locks, but the plans are not available in New York.
Overall, reviewers say a U-lock is your best bet over a chain because it provides good security with less bulk to haul around. U-locks also typically come with a mounting bracket, which makes them more portable. Cable locks are often compared to U-locks or chains in tests, where they obviously fail miserably. Still, a cable lock is better than nothing, and you can generally pick one up for about $10. Experts say there's no reason to spend more than $10 on a cable lock, since they all give way easily to bolt cutters.
- Get a U-lock over a chain; cable locks are useless. U-locks are most often recommended in reviews. Chains are a good option for securing several bikes together, but they are heavy and not as portable as U-locks. Manufacturers tout several shapes of link material (round, square or six-sided) that they say repel the teeth of a bolt cutter, but a large enough bolt cutter can bite onto any shape chain.
- Look for hardened steel. The basic idea is to use steel as hard as the hacksaw blade or bolt cutters that thieves use. A hardened lock casing is needed to repel attack with a drill bit. Based on reviews, it's clear (although unfortunate for bikers) that strength and weight are inexorably linked.
- Look for a sturdy mounting bracket. This ensures you can carry the U-lock on your bike rather than in a backpack.
- Get at least two keys. Most bike locks come with at least two keys, but three or four keys aren't uncommon. This lets you leave one key at home in a secure place in case you lose the primary key. Some keys are lighted, which is helpful for night rides.
- Reviewers also like sliding dust covers that protect the keyhole. A layer of protective plastic that keeps the lock from scratching your bike is another nice feature. With chains, the better models come in a nylon sock that prevents scratching.
- A snug fit is better. A slack chain or too-large U-lock leaves room between the bike and a post -- enough room for someone with a crowbar to begin an assault. There are "noose"-style chains that include a larger link at one end that slides over the smaller links, so the chain can be drawn tight.
- Consider two U-locks, or a U-lock and a chain lock. A U-lock will fit around your frame and rear wheel, but your bike seat and front wheel are still easy to access. Consider adding a secondary lock to protect these areas.
Additional factors to consider are in-house rating systems and approval from independent testers. Kryptonite, for example, rates their own products on a 12-point scale, with 12 being the most secure. That gives you a relative idea of how the manufacturer positions its own products. OnGuard uses a five-point scale, with five stars being the best. Independent testers, meanwhile, use a variety of scales, such as Sold Secure, an English company that uses gold, silver and bronze ratings, or the ART Foundation, a Dutch company that judges locks on a four-point scale, with four-plus being their best rating. For others, like Classe SRA (an independent tester from France), it's pass or fail: locks either have their stamp of approval or they don't.
Finally, you want a lock that nobody can pick with a Bic pen or anything else. You can find many sites on the Internet that teach the curious and the corrupt how to reduce the number of combinations on a combination lock down to about a 30-minute trial-and-error process, but that still seems to be easier than outwitting a key lock -- although information on doing that is also available online. Generally, though, picking a lock takes a practiced hand or special locksmith tools and takes more time than a bolt cutter. Because of that, the strength of the lock is usually the determining factor. On the other hand, most of the thousands of bikes swiped each day, experts say, are those that were left unlocked in the first place.