Perth: You’re standing at your front door, facing a five kilometre commute to work. But you don’t have your car, and there’s no bus route. You can walk for an hour – or jump on your bicycle and arrive in 15 minutes, barely breaking a sweat.
Many people would make the same choice. It’s estimated that there are more than a billion bikes in the world. Cycling represents one of the most energy-efficient forms of transport ever invented, allowing humans to travel faster and farther while using less energy than walking or running.
But why exactly does pedalling feel so much easier than pounding the pavement? The answer lies in the elegant biomechanics of how our bodies interact with this two-wheeled machine.
At its heart, a bicycle is wonderfully simple: two wheels (hence “bi-cycle”), pedals that transfer power through a chain to the rear wheel, and gears that let us fine-tune our effort. But this simplicity masks an engineering that perfectly complements human physiology.
When we walk or run, we essentially fall forward in a controlled manner, catching ourselves with each step. Our legs must swing through large arcs, lifting our heavy limbs against gravity with every stride. This swinging motion alone consumes a lot of energy. Imagine: how tiring would it be to even swing your arms continuously for an hour?
On a bicycle, your legs move through a much smaller, circular motion. Instead of swinging your entire leg weight with each step, you’re simply rotating your thighs and calves through a compact pedalling cycle. The energy savings are immediately noticeable.
But the real efficiency gains come from how bicycles transfer human power to forward motion. When you walk or run, each footstep involves a mini-collision with the ground. You can hear it as the slap of your shoe against the road, and you can feel it as vibrations running through your body. This is energy being lost, literally dissipated as sound and heat after being sent through your muscles and joints.
Walking and running also involve another source of inefficiency: with each step, you actually brake yourself slightly before propelling forward. As your foot lands ahead of your body, it creates a backwards force that momentarily slows you down. Your muscles then have to work extra hard to overcome this self-imposed braking and accelerate you forward again. Instead of a collision, you get rolling contact – each part of the tyre gently “kisses” the road surface before lifting off. No energy is lost to impact.