Screw type built-in anti-theft lock for bicycle

A spiral type concealed anti-theft lock for bicycle is provided, which comprises a lock body, a lock barrel, a clamp, and a tamper-free pin, wherein, a cylindrical internal thread hole is machined at the center of the lock body, the spring lock barrel is in cylindrical form, with thread on surface, and is inserted into the lock body; the marbles in the lock barrel are in flat leaf shape; the tamper-free pin is arranged in the lock barrel and made of an extremely hard material; the clamp is fitted over the lock barrel.. The benefits of the utility model include: simple structure, low cost, and simple process; the tamper-proof pin design enhances protection against destroy by force.. The anti-theft lock can be used on bicycles, light-type motorcycles, tricycles, and automobile steering wheels, and has a wide application range..