The BMW R12 and R17 are

flat-twin engine A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both pistons move inwards and outwards at the same ti ...

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

s made by

BMW Motorrad BMW Motorrad is the motorcycle brand of BMW, part of its Corporate and Brand Development division. It has produced motorcycles since 1923, and achieved record sales for the fifth year in succession in 2015. With a total of 136,963 vehicles sold i ...

from 1935 through 1942. They were developed in 1935 based on the R7 concept of 1934. A few hundred R17s were made, ending in 1937, while the R12 continued through 1942, with a total of 36,008 produced.

R7 concept

The BMW R7 was conceived in 1933 by engineer and designer Alfred Böning, with an

Art Deco Art Deco, short for the French ''Arts Décoratifs'', and sometimes just called Deco, is a style of visual arts, architecture, and product design, that first appeared in France in the 1910s (just before World War I), and flourished in the Unite ...

mathematical geometric basis of his design. Only one R7 was ever made, which Böning disassembled and stuck away with design plans in a BMW warehouse. It was discovered more than seventy years later, in 2005. Hans Keckeisen in Munich began a restoration on behalf of the

BMW Museum The BMW Museum is an automobile museum of BMW history located near the Olympiapark in Munich, Germany. The museum was established in 1973, shortly after the Summer Olympics opened. From 2004 to 2008, it was renovated in connection with the cons ...

, completed 2012. After appearing in European bike shows, restored 1934 R7 was first shown in the US at the

Pebble Beach Concours d'Elegance The Pebble Beach Concours d'Elegance is an automotive charitable event held each year on the Pebble Beach Golf Links in Pebble Beach, California. It is widely considered the pinnacle event of its kind and one of the most prestigious car events in ...

. Böning's new hydraulic fork design of the 1934 R7 went into production the following year, in the 1934 R12 and R17.

R12 and R17

On 14 February 1935, BMW presented the R12 together with the R17 on the German Automobile Exhibition in Berlin for the first time, being a direct successor to the BMW R11. This and the R17 were the first in the world being produced with hydraulically damped telescopic forks. By 1942, the total number of BMW R12 motorcycles manufactured was 36,000. For military purposes, the single carburetor ''Einvergasermotor'' was only available for the R12.

Engine

The engine, designated ''M 56 S 6'' or ''212'', was a twin-cylinder boxer configuration -

four stroke A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either directi ...

with a flathead design. The BMW R12 with two carburetors used a battery and coil ignition, while R12s with a single carburetor used a magneto ignition, capable of working independently from the battery.

Drive

The BMW R12 had a four-speed manual gearbox, operated by a hand shift lever on the fuel tank's right side. Several detail variations were seen in production. In common with most

BMW Motorcycles BMW Motorrad is the motorcycle brand of BMW, part of its Corporate and Brand Development division. It has produced motorcycles since 1923, and achieved record sales for the fifth year in succession in 2015. With a total of 136,963 vehicles sold i ...

, final drive was via shaft, with the

drive shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power and torque and rotation, usually ...

on the right side of the motorcycle.

Suspension and brakes

Front suspension used a telescopic fork, while the frame was rigid with an un-sprung rear end supporting the final drive and a sprung seat for the rider. The R12 used

drum brakes A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum. The term ''drum brake'' usually means a brake in which shoes press on the inner surfac ...

front and rear. Many R12's were equipped with a

sidecar A sidecar is a one-wheeled device attached to the side of a motorcycle, scooter, or bicycle, making the whole a three-wheeled vehicle. A motorcycle with a sidecar is sometimes called a ''combination'', an ''outfit'', a ''rig'' or a ''hack''. ...

attached to the motorcycle's right side.

Specifications

Surviving motorcycles

A BMW R12 is in the

Museum of Military History The Museum of Military History – Military History Institute (german: Heeresgeschichtliches Museum – Militärhistorisches Institut) in Vienna is the leading museum of the Austrian Armed Forces. It documents the history of Austrian ...

Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...

, in its original camouflage. In 2018, an American company created a modified

BMW R nineT The BMW R nineT is a standard motorcycle made by BMW Motorrad since 2014. It is a retro styled roadster marketed by BMW to custom builders and enthusiasts as a "blank canvas for customizing". All models have anti-lock braking systems (ABS). Aut ...

with a close resemblance to the original R7, showing the R7-inspired

custom Custom, customary, or consuetudinary may refer to: Traditions, laws, and religion * Convention (norm), a set of agreed, stipulated or generally accepted rules, norms, standards or criteria, often taking the form of a custom * Norm (social), a r ...

at several shows and museums, and selling kits or complete bikes to the public.

References

{{WWIIGermanVehicles R12 World War II military vehicles of Germany Military motorcycles Research and development in Nazi Germany Motorcycles introduced in the 1930s Military vehicles introduced in the 1930s