Motorcycles | 24 September 2015BMW’s Single-Cylinder R24 Share article facebook twitter google pinterest BMW has made some amazing automotive, technological, and aesthetic advancements throughout its history. Ian Falloon’s new book, The Complete Book of BMW Motorcycles: Every Model Since 1923, showcases those changes. The book is truly the ultimate resource for the fantastic motorcycles built by Germany’s leading motorcycle manufacturer. The following excerpt from Falloon’s book gives us a look at BMW’s first postwar motorcycle, the single-cylinder R24. BMW’s first postwar motorcycle was the single-cylinder R24. This was quite similar to the prewar R23 but included a new engine and bolted-together frame. Source – BMW Group Archives When BMW decided to resume motorcycle production after the war, Allied requirements initially restricted the displacement to 60cc. BMW wasn’t interested in such a small displacement motorcycle, but in 1947 it was permitted to build a small number of prewar R23s out of spare parts in warehouses. This led to the limit being raised to 250cc, but as all the production drawings were lost to the Soviets when they took over the Eisenach factory, BMW stripped down a prewar R23, minutely measuring each part. New drawings were complete by summer 1947, but a complete machine took another year to materialize. When the R24 was first shown in the Geneva Show in March 1948, most of the basic components were missing (but disguised by wooden mockups), but at the Export Fair in Hanover in May, it was only minus a gearbox, gearwheels, and crankshaft. There was an overwhelmingly positive response to the R24, with 2,500 advance orders, but material shortages delayed production until December 1948. The R24 engine followed the form of the R23’s, but apart from the same bore and stroke, it was otherwise new. Positioned above and to the left of the five-section crankshaft, the chain-driven camshaft drove pushrods enclosed in separate tubes. Unlike in the R23, pillars rising above the cylinders supported the rockers. The carburetor was a Bing, and the power increased to 12 horsepower. Source – BMW Group Archives 1949 R24 Although based on the R23, the R24 engine featured a number of new components and design features, notably a new cylinder head, strongly influenced by the design of the wartime R75. The valve angle was altered, the rocker arm bearing blocks were bolted-on pillars rather than cast bosses, and the pushrods were inserted through tunnels in the cylinder head. Like the R75, the valve covers were in two pieces, held by a clamp with a single bolt. The compression ratio was increased slightly, as was the power, and drive was by a four-speed gearbox, while at the front of the crankshaft was a Noris dynamo, with the battery ignition incorporating centrifugal advance. The chassis was similar to the R23, with a bolted rigid tubular-steel frame and telescopic front fork. Also inspired by the R75, the bolted cradle frame allowed easier maintenance, but this didn’t appear on any other model. Extremely popular with German authorities, the R24 retained the black wheel finish and distinctive fishtail muffler. Source – BMW Group Archives With a chromed fishtail exhaust and trim embellishments on the fenders, the finish and appearance were of high quality. And although the R24 was also the most expensive German motorcycle, Schorsch Meier’s exploits on the 500 Kompressor boosted sales and 9,400 R24s were sold in 1949. By now 800 workers were building 50 R24s a week, helped by the acquisition of new machine tools to replace those lost in reparation. R24 production continued until May 1950, when the R25 replaced it. The rigid rear end and shaft final drive was very similar to that of the R23. A useful addition on the R24 was the incorporation a spring and cush drive to spread the drive load. Source – BMW Group Archives The Complete Book of BMW Motorcycles: Every Model Since 1923 Author: Ian Falloon Get a close look at every production motorcycle ever built by BMW. The Complete Book of BMW Motorcycles is a thorough year-by-year guide to every production machine ever built by Germany’s leading motorcycle manufacturer. All the classic bikes are here–pre-World War II BMWs such as the R5 that defined performance in that era; the military R12 that carried the Wehrmacht as it blitzkrieged its way across Europe; the Earles-forked R69S that offered the perfect platform for mounting a Steib sidecar; the R90S cafe racer; the K1 “flying brick”; and the GS (Gelände Sport) series that launched a dual-sport revolution, right up to today’s world-class S1000RR. All of BMW’s bike families are covered–the side-valve machines from the early years, the early overhead-valve performance bikes, the postwar Airheads and Oilheads, the four- and six-cylinder touring bikes, the early pushrod singles, the modern overhead-cam singles, the latest parallel twins, and inline four-cylinder sport bikes. From the first model, the R32 that launched BMW’s motorcycle dynasty, to the latest (and fastest) model, the World-Superbike-dominating S1000RR, The Complete Book of BMW Motorcycles captures nearly a century of motorcycling excellence with a combination of historic and contemporary photos. Complete technical specifications for each model make this book a must-have for any serious BMW aficionado. Don’t miss the most thorough reference to these outstanding German motorcycles available today! 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