question_answer

When brakes are applied in a bicycle, the brake shoes apply frictional force on the wheels. The forces are internal for the system (bicycle). For retardation, external forces must act on the system. The force of friction at the road surface remains the same before and after the brakes are applied\[(f=\mu R)\]. How does the bicycle stop?

Answer:

                When brakes are applied, the wheels are prevented from rolling. During rolling, the friction at the road surface does not cause retardation. When rolling is prevented, the wheels have to slip on the road. The friction of the road now causes retardation.