What’s so good is that they get you places quickly without gobbling up fossil fuels like gasoline, diesel, and coal or creating pollution. They do that because they very efficiently convert the power our bodies produce into kinetic energy (energy of movement). In fact, as you can see from the chart below, they’re the most efficient transportation machines humans have developed so far. Harnessing the power from your muscles in an amazingly effective way, a bicycles can convert around 90 percent of the energy you supply at the pedals into kinetic energy that powers you along. Compare that to a car engine, which converts only about a quarter of the energy in the gasoline into useful power—and makes all kinds of pollution in the process.
Look at it this way: If you drive a car, you’re dragging a lump of metal that probably weighs 10–20 times as much as you do wherever you go (a typical compact car weighs well over 1000kg or 2000lb). What a waste of energy! Go by bike and the metal you have to move around with you is more like 6–9kg (14–20lb) for a lightweight racing bike or 11–20kg (25–45lb) for a mountain bike or tourer, which is a fraction of your own weight.
Better efficiency means you can go further on the same amount of fuel, which is another great advantage of bikes, although a little hard to quantify. According to the classic bikcycles Science book by David Gordon Wilson et al: “A racing bicyclist at 32km/h (20mph) could travel more than 574 kilometers per liter (1,350 miles per US gallon) if there were a liquid food with the energy content of gasoline.” Whichever way you look at it, bikes are pretty amazing!
