In most American cities, commuting by bike is faster and cheaper than driving to work. Now comes another reason to think about pedaling instead of stepping on the gas pedal: people who ride bikes weigh less than people who drive. The Imperial College of London reports that researchers at the school monitored 11,000 volunteers in seven European cities, asking them how they move around the city, which mode of transport they use and how much time they spend traveling. They also asked the volunteers to record their height and weight, and to provide information about their attitudes towards walking and bicycling. The take away: people who drive cars as their main form of transport are on average four kilograms (8.8 lbs) heavier than those who ride bikes.