Abstract: A lock device includes a locking unit, a protective unit surrounding the locking unit, and a key unit extending through the protective unit and engaging the locking unit to lock or unlock the locking unit. The locking unit includes a lock head and a lock core. The protective unit includes a rotation member and a follower. The locking unit is sandwiched between the rotation member and the follower. The rotation member has a central portion provided with a passage aligning with the lock core and has a peripheral wall provided with an opening connected to the passage. Thus, the locking unit is hidden in the protective unit to prevent the lock core from being exposed from the protective unit so that a person cannot see the inner construction of the lock core and cannot unlock the lock core easily.

Abstract: A bicycle includes a frame, a wheel mounted on the frame, a handlebar mounted on the frame, a damping device mounted on the frame and movable to touch the wheel, a control switch mounted on the handlebar, and a connecting wire mounted on the frame and connected between the control switch and the damping device to control movement of the damping device by operation of the control switch. Thus, when the bicycle travels downhill and the rear wheel is rotated at a higher speed, the damping device provides a damping force on the rear wheel to reduce the rotation speed of the rear wheel so as to prevent the rear wheel from being rotated at an excessive high speed when traveling downhill, thereby protecting the rider's safety.