Abstract: 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.

Abstract: The present invention provides a locking system that is more secure and theft resistant than traditional key and cylinder systems. A hidden locking system is provided where access to the locking mechanism is hidden from view and cannot be rotated or engaged by screwdrivers, pens or other common tools. In another aspect the present a primary and all related secondary locking systems on an object such as a bicycle. In a further aspect the present invention provides lockup in applications where large and bulky key and cylinder systems are not possible or practical.

Abstract: A tamper resistant fastener, which can only be rotated with a specific key, is described. The fastener includes a head for rotation about a vertical axis. The head is provided with the least two cutouts in the head of the faster spaced away from the vertical axis, the cutouts having a discontinuous sidewall. The side wall of each of the cutouts has a first generally vertical engaging surface for engagement by a mating member on a specific key for clockwise rotation of the head about the vertical axis and a second generally vertical engaging surface for engagement by the mating member on the specific key for counter clockwise rotation of the head about vertical axis. The side wall of the cutout is interrupted adjacent the second engaging surface to prevent engagement by a tool other than the specific key and thereby prevent rotation of the fastener in a counter clockwise direction by a tool other than the specific key.

Abstract: A device for locking bicycle components to the bicycle frame comprises a threaded bolt with a corresponding nut having a rotatable casing surrounding the outer surface thereof and a key for engaging the nut. The key and the end face of the nut have at least one spigot and at least one hole such that the spigots of each fit into the holes of the other. When so engaged, the key is capable of turning the nut. The key preferably includes leverage arms for aiding the turning of the nut.