The U-Lock has been the number one lock in the fight against bicycle thieves for many years. Although U-locks are relatively heavy and somewhat bulky, they are secure, and many models come with a bracket for rattle-free transport on the bike. A shackle made of different hardened steel alloys resists violent opening attempts well. High-quality locks also rely on locking cylinders that rotate, which make opening the lock much more difficult to pick even for experts. Manufacturers such as Abus, Trelock and Kryptonite have repeatedly been able to demonstrate their expertise in tests with their well-thought-out shackle locks. Make it really hard for bicycle thieves and secure your bike with a suitable U-lock on a solid object.