For nearly 80 years, shaft-drive boxer twins have traditionally formed the backbone of the BMW motorcycle line-up. For many enthusiasts of the Bavarian marque the classic BMW twin was the R90S of 1973-76. Over the decades, successive generations of durable machines - including the R100S, fully-faired R100RS, four-cylinder K-series, high-performance R1100RS and an entire family of touring and sporting models ranging from 850 to 1200cc - would ensure the BMW boxer twins a place in the Haynes Great Bikes series. This book covers: historical context, racing, the wartime R75 and R69S; the 75 series which enabled BMW to compete with the high-performance Japanese machines; the R90S, the 76 and Superbike performance; the R100RS, the 77 and the touring R100RT; smaller twins, smaller potential; the R89G/S, including a Paris-Dakar version; rationalization of the boxer range, and the new twins that included four-valve heads and electronic engine management; and technical specifications from 1969 to 2003.