Long before the mountain bike entered our global consciousness, the cycling enthusiasts of Northern California's Marin County rode modified pre-WWII bicycles down the slopes of Mount Tamalpais. They developed their bikes through rigorous field-testing, often risking life and limb to do so. Some of these cyclists were Category-1 road racers looking for a new way to train during the off-season. Others were simply fun-loving hippies looking for a new way to commune with nature. Their early bikes were scavenged from dumpsters and junkyards. It was from these humble beginnings that a multi-billion dollar industry, a form of recreation for the masses, and an Olympic event, were born. These hefty steeds were affectionately known as Klunkerz.

"In the late 1960s through the 1970s a group of cyclists in Northern California's Marin County turned the bicycle world upside-down by taking their adventures off-road."