Before Mountain Biking Became One of the Most Popular Recreational Sports, Adventurous Souls of the American West Had to Invent a Rugged Bike
The origin story has two settings: In Colorado, a gang of riders had the tenacity to conquer a treacherous terrain, and in California, others had the technology to design the ideal ride
We haven't written up this one. Smithsonian has the full story — the link below goes straight to it.