Slaying the Badger, by Richard Moore - a must read if you have a competitive bone in your body
Rough Ride, by Paul Kimmage - the truth about pro riding
Half Man, Half Bike, by William Fotheringham - the life and career of Eddy Merckx
Major, by Todd Balf - another fine book about the times of Major Taylor, every bicyclist should read this book
The Giro d'Italia (1949), by Dino Buzzati - translated from the Italian language, it's a compendium of daily entries. Vague, poetic, romantic, frustratingly verbose - it's torture to read. About Coppi vs Bartali, though, so there's that.