What was the name of the first mass-produced mountain bike, introduced in 1981?

The first mass-produced mountain bike, introduced in 1981, was the Specialized Stumpjumper.

Specialized developed the Stumpjumper as mountain biking was emerging from Northern California’s rough-trail riding culture. The model was based on an earlier custom design associated with Tom Ritchey, Gary Fisher, and Charlie Kelly, while Tim Neenan worked on the production design. Specialized founder Mike Sinyard wanted to offer a custom-style off-road bicycle on a repeatable production basis.

The first Stumpjumpers were built in Japan with welded steel frames. They had no suspension and used parts adapted from road, touring, BMX, and motorcycle applications, including 15-speed Suntour gearing and cantilever brakes. The original bicycle weighed just under 30 pounds.

About 500 bikes from the first production run were imported into the United States over the following year. The first shipment of 125 sold out in six days, helping demonstrate that mountain biking could support a mass-market bicycle category. Earlier production mountain bikes existed, but the Stumpjumper is widely recognized as the first mass-produced mountain bike.