1937 BMW R6: A Rare Gem in Pre-War BMW Collections

Among the distinguished assemblages of pre-war BMW motorcycles—the 1937 BMW R6 stands out as a "one-year wonder." Produced solely in 1937 with approximately 1,850 units built, this model represents BMW's first venture into 600cc displacement and a transitional design bridging sporting innovation with practical touring. Its extreme rarity—estimates suggest fewer than 50 to 100 surviving examples worldwide, with around 10 in the United States—makes it a prized centerpiece in collections focused on BMW's interwar engineering evolution.

Introduced in 1937, the R6 followed the groundbreaking 1936 R5, sharing its advanced all-welded tubular steel frame derived from BMW's supercharged racing machines. While the R5 was a high-performance overhead-valve sports bike, the R6 positioned itself as a more versatile tourer, often suited for sidecar use, powered by a side-valve (SV) flat-twin engine. 

The R6 is powered by a 594cc (or 599cc in some references) air-cooled, four-stroke, side-valve flat-twin boxer engine with a long-stroke configuration (70mm bore x 78mm stroke). It produces 18 horsepower at 4,500 rpm. A four-speed foot-operated manual gearbox with dry single-plate clutch drives the shaft final drive, enabling a top speed of around 125 km/h (77 mph). The bike weighs approximately 175 kg (385 lbs) curb, with a fuel capacity of about 15 liters (3.96 gallons). 

The R6's standout elements include its innovative tubular frame for superior handling, foot-shift gearbox, and elegant details like fish-tail silencers and two-tone painted rims inherited from the R5. The central air filter on the gearbox housing and toe-operated foot brake further enhanced usability. Though lacking rear suspension, the lightweight frame and telescopic forks provided excellent road manners for the era. As BMW's inaugural 600cc model, the R6 influenced subsequent designs like the R61 and R71, contributing to the brand's reputation for reliable shaft-drive boxers. 

This R6 is an exceptional example and a great find.