OnGuard Pitbull STD 5003 U-lock

Experts agree that no bike lock is impenetrable. However, some locks resist would-be thieves better than others. U-locks are better than cable locks, but the toughest ones tend to be expensive and heavy. The top-performing Kryptonite New York Fahgettaboudit U-lock, for example, costs about $75 and weighs close to five pounds. However, if you're on a budget, reviewers say the OnGuard Pitbull STD 5003 U-lock, which weighs about 3 pounds, provides good value for a reasonable price. Tests show it's able to resist attacks with hand tools, making it better than many other U-locks and far better than any inexpensive cable lock. On the downside, tests show it can be quickly cut with power tools, and the anti-theft warranty is void in New York state.

Cycling Plus magazine from the U.K. and Australia's Ride On magazine have the best reviews of the OnGuard Pitbull STD 5003, showing how well it resists attacks compared to others. BikeRadar.com (from the publisher of Cycling Plus magazine) also rates this product favorably after testing, giving it an above-average rating.