Cycling is widely regarded as one of the most energy-efficient ways to travel, allowing people to cover more distance and move faster while using less energy compared to walking or running. Globally, there are more than a billion bicycles in use, highlighting its popularity and practicality. In terms of energy efficiency, cycling is at least four times more efficient than walking and eight times more efficient than running. This is due to the way bicycles reduce the major energy drains associated with human movement. When walking or running, each step involves a small collision with the ground, which causes energy to be lost as sound and heat. Additionally, with every step, a person slightly slows themselves before moving forward again, which requires extra muscular effort to overcome and accelerate. Bicycles, on the other hand, use wheels to eliminate these issues. The rolling contact of wheels avoids the collision with the ground, and the force from pedaling is directly translated into forward motion without energy loss from impact. Human muscles have a natural limitation: the faster they contract, the less force they can generate, and the more energy they consume. This is why sprinting is more exhausting than jogging or walking. Bicycle gears help overcome this challenge by allowing cyclists to shift into higher gears as they increase speed. This means the cyclist's muscles don't have to contract as rapidly, keeping them within an optimal range for both power and energy efficiency. Despite its advantages, cycling is not always the best option. On very steep hills with a gradient of more than about 15 percent, cycling becomes less effective because the legs have difficulty generating enough force through the circular pedaling motion to ascend. In such cases, walking or climbing may be more practical. Conversely, walking down steep slopes becomes more challenging when the gradient exceeds about 10 percent, as each step creates jarring impacts that waste energy and strain the joints.