RockyMounts Warrant U-Lock
Serious bike lock security is challenging for two reasons. First, useful high security locks are generally very heavy, making portability a major issue. Second, if you have manageable high security, the design must be useful in real life applications. Enter the RockyMounts Warrant U-Lock. With more of a square-shaped "U" in the 14mm hardened steel shackle, the Warrant offers greater locking usefulness and rates out at a seriously stout Security Level of 8.
The dimple key and cylinder design is simple and easy to use, and contributes to the overall security rating. Three keys provided allow you store one in your sock drawer for safe keeping. RockyMounts covers the shackle and lock stock with molded silicon, which offers great grip in wet or dry conditions, something you will thankful for when handling this beast. The Warrant was also designed for potential pocket use, with a shackle size of 79mm x 130mm, though we recommend reinforced stitching.
The internal shackle shape of the Warrant caught our eye from the get-go. Compact, high-security u-locks can be less useful than desired, but the squared off shape offers more usable space.