Patent attributes
A bicycle lock includes a U-shaped body and a pivotal portion pivotably connected to the first end of the U-shaped body. A head is formed on the second end of the U-shaped body and includes a lock unit received therein. The lock unit includes a nut and a core unit which is co-rotated with the nut. The nut is rotated by using a key. The core unit includes a core and a restriction plate which is co-rotated with the core and includes a notch. A safety unit is received in the lock unit and includes an engaging member and a resilient member which biases the engaging member to be engaged with a notch of the restriction plate to prevent the core unit from being rotated. The engaging member includes a protrusion which contacts the outer periphery of the nut to prevent the nut from being rotated by unauthorized tools.