It was quite a feisty engine, though, and not every bike model could handle it. To better accommodate the Shovelhead, Harley-Davidson released a factory chopper in 1971: the FX Super Glide.

That "Captain America" chopper ridden by Fonda's character might be the single most iconic motorcycle of the tumultuous ... aging panhead V-twin with the new shovelhead, bumping output from ...