Plump, grumpy, slumped on the couch, and going nowhere fast at age 16, Phil Gaimon began riding a bicycle with the grand ambition of shedding a few pounds before going off to college. He soon fell into racing and discovered he was a natural, riding his way into a pro contract after just one season despite utter ignorance of a century of cycling etiquette. Now, in his book Pro Cycling on $10 a Day,...