This 1970 Husqvarna 250 Cross belonged to Bruce Brown and appeared in On Any Sunday. It is now part of the Petersen Automotive Museum?s collection. Photos by TED7 / Courtesy of the Petersen Automotive Museum.

For a while there, 50 years ago, Husqvarna was perhaps the best-known and most desirable dirtbike in the world. They were good enough bikes ? I owned and tested them in the day ? but fame earned in the hands of Baja racer and ISDT gold medalist Malcolm Smith, and their use by actor Steve McQueen, exposed and validated the bikes to more people through the movie On Any Sunday than probably any amount of advertising or editorial coverage could accomplish. Whereas magazine tests and race results reached readers hungry for the latest news about the latest products, such impressions often vaporize when the next generation of products arrives. And from the mid-1960s onward until the modern 4-stroke dirtbike era, those changes were relentless. 
What the movie actually did for the Scandinavian machines was far deeper, what scientists would define as ?imprinting.? In 1935, Austrian zoologist Konrad Lorenz noticed that goslings (newly hatched geese) would memorably imprint on the first living animal they saw, whether that was Mother Goose or a person. This imprint became lifelong, the same powerful imprint that Husqvarna?s heroic and emotional appearances in On Any Sunday created for kids and young adults at the time. And so, all these years later, the effect Husqvarn...