Bicycle Lock

A bicycle lock is a security device used to prevent bicycle theft, generally by fastening the bicycle to a fixed object, e.g., a bike rack.

An inherent challenge to bicycle theft prevention is the detatchability of the wheels from the frame. Unless both wheels and frame are secured, wheels can be removed separately. An optimal locking method will secure the frame as well as both wheels — either to a fixed object or to each other.

Locking devices vary in size and security; the most secure tending to be the largest, heaviest and least portable. Lesser equipment is used to deter attempts by less skilled and determined thieves. Thus like other security equipment, bicycle locks must compromise between security, portability and cost. Some are made of particularly expensive materials chosen for their acceptable strength and low density.

An alternate defense is the provision of bicycle lockers in which the whole bicycle is locked. This also safeguards equipment such as lamps, tools, spare tubes etc., against all but the most industrious thief, or one equipped with heavy equipment or power tools. Bicycle lockers, however, generally take up much more space than exposed bicycle racks, limiting potential storage capacity in a given space. An alternative is a card-access bike cage such as is present at Alewife station in Cambridge, Massachusetts. In addition to a bike lock, bike registry can further assist in providing recovery in the event of theft.

Test standards that rate the effective security of bicycle locks are provided by Thatcham and Sold Secure in the United Kingdom, ART in the Netherlands, SSF in Sweden, and VDS in Germany. Tests carried out by the Cyclists' Touring Club showed that all of the locks under test could be broken in less than 42 seconds using either bolt croppers for a cable/chain or a bottle jack for D-locks.