Well, I see where you've already ruled out any possibility of exercise along with that obvious benefit of gas miserliness. (By the way, I ride a 21-speed hybrid bike 15 minutes to work, and I don't wear spandex. It's blue jeans and a polo shirt. But, hey, you're right and I'm wrong about us and our motivations.)
Why are we here instead of DU? Must be because we simply enjoy the conversation with your sort of Neanderthal. Here's one you'll enjoy: "Use oil. Make a terrorist happy."