While no bike lock is impenetrable, a top-rated lock can provide substantial protection. A hard-to-crack lock may be recognized by thieves and not considered worth the effort. U-locks, which are also called D-locks, are thought by many to be the best defense against bike theft.
If you live in an urban area and need serious security for your bike, the best-reviewed bicycle lock is the Kryptonite New York Fahgettaboudit Mini (Est. $70) . It's the leader in several performance tests conducted by a variety of national publications. In a Men's Journal evaluation of three U-locks, the Fahgettaboudit Mini lasts the longest against power tools and a professional safe-cracker can't pick it. In tests at Slate.com, Scott Elder says it would have taken almost 45 minutes with a hacksaw to crack the 18 mm steel shackle.
However, reviewers disagree on the lock's ease of use. Weighing 4.5 pounds, the Kryptonite New York Fahgettaboudit Mini is smaller than other locks and a few owners say that makes it difficult to secure anything but the bike frame. Others praise the small design, saying it's easier to transport and makes it difficult for a would-be thief to get a tool between the lock and post.
The Fahgettaboudit Mini comes with three keys, one of which has a light. Owners like that its hardened steel helps resist bolt cutters, and appreciate additional features such as a protective vinyl coating and sliding dust cover. Consumers can register for up to $4,500 of anti-theft protection by mailing copies of their receipt within 15 days of purchase. This coverage is higher than most comparable locks, but many find the process cumbersome and practically useless since pieces of the broken lock must be sent to Kryptonite as "proof of lock failure." Because many thieves don't leave evidence behind, you may not be able to take advantage of the insurance offer.
Kryptonite's New York Standard U-Lock (*Est. $60) also gets good reviews and weighs slightly less at 3.9 pounds. It's sometimes called the New York 3000 because of its $3,000 anti-theft protection warranty. The Standard has a longer shackle that's 4 inches wide by 8 inches long on the inside, compared to the Fahgettaboudit Mini's 3.25 by 6 inches. As a result, the New York Standard can be locked around thicker poles and bike frames, making it a favorite of bicyclists who need more space.
The New York Standard U-Lock features top-of-the-line materials and is easy to use, and owners like its protective vinyl coating and dust cover. The hardened steel shackle is 2 mm thinner than the Fahgettaboudit Mini. It comes with an EZ-mounting bracket, but it gets less-than-stellar reviews and some consumers call it "flimsy."
Other U-locks also impress reviewers; the OnGuard Brute STD (*Est. $70) performs nearly as well as the New York Fahgettaboudit Mini in several tests. After evaluating a few of the most popular U-locks, Slate.com's Elder says the Brute is the "toughest-looking lock in the bunch and one of the toughest-acting." It gets great marks for security; Elder can't saw through the 16.8 mm shackle or dislodge the lock with a hammer. However, he says the transportation bracket doesn't seem sturdy enough to hold the 4.3-pound lock.
In fact, owners of the Brute STD complain that it's heavy and easily falls from its mounting attachment, requiring transport in a backpack or basket instead. Still, most give it high ratings based on toughness. Testers for The New York Times like the long shackle that allows you to lock the frame and rear wheel to a stationary object, but agree that the Brute STD is large and difficult to carry. The lock comes with a $5,000 one-year theft protection plan that isn't available to customers in the state of New York.
One downside of a typical U-lock is that it leaves your front wheel and bike seat vulnerable; you can fit the lock only around your bike frame and rear wheel. One solution is the OnGuard Bulldog (*Est. $45) , a U-lock with a 13 mm shackle that comes with a separate cable lock for securing additional components. We found good reviews for this lock, but owners complain that the key gets stuck or breaks off in the locking mechanism. The Bulldog DT comes with up to $1,501 of anti-theft protection, but it isn't available in New York.
Comparatively, the Blackburn San Quentin (*Est. $90) , which weighs just over 3 pounds, has a longer shackle (7.8 inches). The San Quentin does not sacrifice any strength though, performing extremely well in expert tests thanks to its 18 mm width.
Among very small and light U-locks, the OnGuard Bulldog Mini TC (*Est. $30) gets decent reviews. It's not as tough or durable as OnGuard U-locks in the Brute series, but it's a good choice for a low-crime area or if you want an easily transportable lock at a low price. The Bulldog Mini weighs less than 2 pounds, has a 13 mm shackle and is about 3.5 inches wide by 5.5 inches long. Its $1,500 of anti-theft protection doesn't cover New York customers, and it comes with five laser-cut keys and a mounting bracket. The lock gets excellent ratings in owner reviews compiled by Buzzillions.com and at Amazon.com. However, at least two say the bike lock can rust after being left out in the elements, and a few others report that the keys broke in the lock.