Abstract: A locking device for a bicycle employs a large diameter flexible steel cable such as a 7/16 inch diameter cable. A storage reel for the cable is hinged to the bike frame and sized to contain loops of the cable when not in use. The storage reel desirably fits partially within the outline of the bicycle frame between the bicycle seat and the steering column to minimize interference with the use of the bicycle. One end of the cable is secured to the reel and the free end can be wrapped around a structure to prevent theft of the bicycle and then inserted in a socket mounted on the bicycle fork. A plug on the end of the cable interfits in the socket and registrable apertures on the tube socket and the plug enable a padlock shackle to be inserted through the apertures to secure the free end of the cable to the bicycle.