Due to the popularity of Bernt Spiegel's The Upper Half of the Motorcycle in its original German, leading to multiple editions and printings, the book has been translated into English to bring its provocative message to a wider audience. Spiegel's metaphor considers the rider and the motorcycle as a single unit, the rider being the upper half. Taking a multidisciplinary approach, Spiegel draws on anthropology, psychology, biology, physics, and other disciplines to analyze the theory and function of the man-machine unit. Motorcycle riding is seen as a serendipitous junction where people have created machines for personal transport and then become so adept at using them that the machine becomes like an artificial limb -- part of the rider himself. The ultimate goal for riders is the integration of the man-machine interface and skill development to the point of virtuosity. Spiegel considers the various aspects of motorcycle riding that must be understood, practiced, and mastered before virtuosity can be attained. Many anecdotes, supplementary material, and in-depth treatment of specialized topics is contained in sidebars and footnotes. Numerous diagrams and photographs illustrate the book's principles.