What is the principle of bicycle pedal?

Pedal components are assembled on the left and right cranks of the central shaft, and are devices that convert horizontal force into rotational force. When riding a bicycle, the pedal force is first transmitted to the pedal parts, and then the pedal shaft drives the crank, the central shaft and the chain flywheel to rotate, so that the rear wheel rotates, thus making the bicycle move forward. Therefore, whether the structure and specifications of pedal parts are appropriate will directly affect whether the cyclist's feet are straight and whether the bicycle can run smoothly.