The development of the BMW-R75
Back in the Thirties, many European Armies began to
improve mobility of their infantry by employing sidecar-motorcycles. In 1935
the German Army started their drafting program and motorcycle troops were
established. Their goal was to bring three fully equipped soldiers up to the
front line in very short time.
In the first year of World War II civilian motorcycles were (confiscated)
painted army-grey and military equipped. Due to the great variety of models,
many vehicles failed after short time on duty as spare part availability
felt short of demand. Employment off-roads and/or extreme climatic
conditions were just too much to cope for many of the civilian-type
motorcycles.
In November of 1937 negotiations took place between OKH (= High Commend Army)
and the industry (BMW and Zündapp) on the subject of
”heavy off-road motorcycle-sidecar rigs for army use”
Following specifications were fixed for the new to develop vehicle:
- the VOLKSWAGEN tire-size 4,50 x 16" had to be used
- front and rear mudguards had to have ample clearance, enough to be fitted with sliding-chains
- tank to hold gasoline for a minimum of 350 km driving distance
- top speed under full load to reach 95 km/h - sustained speed 80 km/h at “Autobahn”condition
- minimum ground clearance to be 150 mm
- total pay-load 500 kilograms, of which 250 Kg (rider, co-rider, bags) for the motorcycle, and 250 Kg pay-load for the side-car.
As in 1939 the German-Army-Administration requested a report of developmental stage, BMW could already present a practical proposal. A sidecar prototype of 1934, designed for winter driving under extreme conditions, using a driven sidecar wheel, caught the attention of the army experts. Years of experimental research made this system ready for production.
This proven technique was an essential feature for the BMW
technicians, in addition to the telescopic front fork developed a few years
before. Compared to former leaf-spring design, its response in off-road
driving was quicker and softer. The frame consisted of a detachable tube
construction.
In spring of 1941 a bike of powerful appearance was ready to be moved to the
front lines. It combined excellent
manoeuverability in addition to all other well known BMW handling features.
Due to encasement of all moveable parts, including telescopic-fork and
universal drive shaft the bike kept insensitive and reliable under all
driving conditions. Even moving with the troops at marching speed for hours,
water-crossings, steep hills climbing, or high-speed driving on the
“AUTOBAHN” did not effect operationall reliability.
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