Best book ever written on cycling, hands down, IMHO, is "The Bicycling Book" edited by John Krausz & Vera van der Reis Krausz. It has a lot of short chapters written by different authors who share a real passion for all different aspects of the sport. There are a lot of really cool chapters including one on Klunkers that covers the early days of mtb riding. There is a also a great chapter on winter riding in Finland and another really cool one on Beryl Burton. Hard to find but there is a lot of cool stuff there.