When you see someone riding a fat tire bike, it's hard not to do a double take. The cartoonishly large tires look so out of place on a standard bike frame that you have to think someone is pulling a prank. Yet these bikes that were initially designed for riding through the snow have become, while perhaps not yet familiar, certainly visible on trails year-round in most parts of the country. Why? They're just fun to ride, whether in snow or on the rough trails in the summer months. You get more traction and grip over rough terrain without giving up much in efficiency.