Image by Axel Bührmann via Flickr Whether you're a need-for-speed roadie, an adrenaline-junkie mountain biker, or a tree-hugging bike commuter, you're riding on a thing with two wheels (unless you're using a tricycle, a tandem bike, or you haven't taken your training wheels off yet). Fact of the matter is, your bicycle runs on tires. And what happens to tires? They become flat. And I'm not…