Allan Girdler, with Photography by David Dewhurst. In 1957 Harley-Davidson bowed to customer pressure and grafted an overhead-valve top end unto the four-cam bottom end of its floundering KL series of middleweight motorcycles. The resulting motorcycle, the Sportster, earned the distinction of being the most iconoclastic motorcycle model ever produced. In continuous production for 44 years and counting, the Sportster long-ago abdicated its original title as the king of high performance motorcycles, yet it remains one of the world's most popular motorcycles, despite using antiquated technology. The elegant simplicity of the Sportster embodies what Robert Persig calls "the a priori motorcycle." That is, when most people close their eyes and conjure up the image of a motorcycle, it is something very similar to a Sportster that immediately springs to mind. It is this raw, essential nature that propels the Sportster to mythic status.'