Abstract: A locking device particularly useful for locking a motorcycle, bicycle or other movable object to a fixed object, comprises a shackle including a pair of rigid, cylindrical bars of strong material pivotally mounted to each other at one end and terminating opposite to the pivotal mounting in a pair of free, inwardly-bent, straight end. The free inwardly-bent ends of the bars are a small fraction of the length of the remainder of the bars and are joined thereto by integrally formed angled junctures. The locking device further includes a locking mechanism enclosed within a housing formed with a pair of openings for receiving the free ends of the shackle bars thereby to lock them to the housing.