Russ Mahon is an avid cyclist and founder of a cycling group known as The Morrow Dirt Club. Originally based in Cupertino, California, The Morrow Dirt Club were, arguably, the first to put multiple gears on pre-World War II balloon-tired bicycles for use off-road. These bicycles were the precursor to the modern mountain bike. Russ, along with Tom and Carter Cox, competed in a race in Mill Valley, California in 1974 on these bikes. It was there that Gary Fisher and Joe Breeze, among others, saw the bikes and developed them into the worldwide phenomenon known as mountain biking. In 2007, Russ Mahon was profiled in the documentary film, Klunkerz: A Film About Mountain Bikes.