Theft -proof device for bicycle

The utility model provides a theft -proof device for bicycle, include a set of ratchet its to set up in frame department is pedal epaxial and pedal big flywheel relative, including ratchet, ratchet wheel seat, two pawls, lock body, lock core shifting block, sour jujube flap, ratchet wheel seat fixes and be hollow structure on the frame, two pawls symmetry sets up inside ratchet wheel seat, but oneend and ratchet wheel seat are connected free swing, one end be provided with the more than one ratchet and be provided with reset spring and ratchet wheel seat inside continuous, the fixed lid of sour jujube flap is on ratchet wheel seat, the lock body sets up on the sour jujube flap, and wherein the lock core shifting block is located in the middle of two pawls, the ratchet is fixed to be cup jointed at pedal axis left end, not portable, ratchet wheel seat sets up at the ratchet peripheral coaxially with the ratchet. The utility model discloses with bicycle style structure as an organic whole, wholly be hidden, do