BMW R32

Date 29.4.2016

Presented by
  • Motorcycle Trader

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The Most Desireable BMW Among Collectors

Although BMW was born 100 years ago, its earliest products were aero engines, with motorcycles following in 1923. Over the subsequent 90 years BMW has produced bikes with single, twin, triple, four and six-cylinder engines, but the enduring layout has been the horizontally opposed “boxer” twin with shaft final drive.

This design has become the trademark that defines the BMW motorcycle and it all began with the R32, which evolved from BMW’s existing fore-and-aft M2 B15 (2 for two cylinders and B for boxer). But as the rear cylinder tended to overheat in the M2 B15-powered Victoria and Helios machines, designer Max Friz decided to mount the engine transversely and add a shaft final drive. The drawings were completed by December, 1922, after just four months.

Although the 1919 Sopwith ABC also featured a transverse twin-cylinder engine (without shaft drive), Friz claimed he was unaware of the ABC at the time he designed the R32. ABC’s designer Granville Bradshaw accused BMW of copying the ABC, but there were too many detail differences for this to be substantiated.

Built With Quality

The R32 68x68mm side-valve engine had a low 5:1 compression and, with a single 22mm BMW Special carburettor, produced a moderate 8.5 horsepower at 3200rpm. This was slightly more than the M2 B15, but while the power output didn’t set the world alight, the R32’s design and execution was ground-breaking. Concentrating on reliability and ease of maintenance, the engine, including the valve timing system, was fully encased.

Thanks to the shaft final drive and inline crankshaft there were no chains requiring adjustment so compared to other 500s, the R32 was revolutionary. A hand lever operated the three-speed grease-filled gearbox, and ignition was by a magneto with a rather complicated set of handlebar controls.

BMW R32

Friz installed this engine in a closed twin-loop tubular steel frame, with the fuel tank beneath the upper frame tubes. The frame was brazed and sleeved, but as the workers lacked experience in brazing, fractures on the solder joints were a problem until the introduction of pressed steel frames in 1929.

The front suspension consisted of a short swinging fork with cantilever leaf springs under the steering stem. The rigid frame meant the driveshaft didn’t require a universal joint, with a rubber disc a sufficient shock absorber.

Initially the only brake was a block operated by the rider’s heel, but by 1925, a front 150mm drum brake was introduced.

The R32 Origins

The R32 (R for Rad meaning wheel but the origin of the ‘32’ remains a mystery) was also surprisingly light at 122kg and offered a top speed of around 90km/h. The low centre of gravity, short 1380mm wheelbase and 26-inch wheels promised safe and manageable handling for a touring motorcycle on the poor roads of the day. In May 1923, Friz himself tested the R32, finishing the “Fahrt durch Bayerns Berge” trial through the Bavarian mountains without incurring any penalties.

BMW R32

The R32 was launched in Berlin that September, one month before the Paris Car Show where it was a star attraction, establishing BMW’s boxer-twin shaft-drive format. Despite its impressive credentials the initial response to the R32 was mixed. Sceptics feared the engine could be easily damaged in a fall, others felt it underpowered, but no one could deny the compact engine and transmission unit was a brilliant design and beautifully executed.

BMW R32

As cars were for the wealthy few, the motorcycle market flourished in Germany during the early 1920s, BMW managing to sell 1500 R32s by the end of 1924, with sales totalling 3090 before production ceased in 1926. Most were sold in Germany and it is estimated only around 60 survive. Despite its modest specification the R32 was the founder of the species and holds a special place in BMW’s history, serious collectors considering it the most desirable of BMW’s motorcycles.

What’s it worth?

The R32’s release coincided with a stabilising in the German currency but at 2200 Marks (or 2600 Marks with light, horn, pillion seat and speedometer) it represented a significant investment in 1924. As it is extremely rare and in demand a R32 would command more than $150,000 today.

The bike featured here sold for $US139,000 in 2011, a world record at the time.

Five things about BMW’s origins

  • BMW’s origins go back to 1913 when Karl Rapp established an aircraft engine factory in Munich. Although his engines were unreliable, in 1916 the Rapp Motor Works received a lucrative war contract. But because of Rapp’s dubious reputation, the Austrian War Ministry insisted on appointing a supervisor, Franz Josef Popp, and in July 1917, the Rapp Motor Works became the Bavarian Motor Works.
  • Slightly earlier, in 1916, engineer and pilot Gustav Otto established the neighbouring Bayerische Flugzeug-Werke (Bavarian Aircraft Works), and although BMW and BFW existed as separate entities until 1922, they would eventually merge.

BMW R32

  • Max Friz joined BMW in 1917, Popp engaging him to redesign Rapp’s problematic six-cylinder engine. The resulting IIIa was so superior to other designs that by the middle of 1918 the Prussian military ordered 2000. Air ace Ernst Udet achieved 30 “kills” with his BMW IIIa-powered Fokker D VII fighter plane.
  • After the signing of the Treaty of Versailles BMW was forbidden from manufacturing aircraft and aero engines until 1920. Salvation came from foreman Martin Stolle, a committed motorcyclist and fan of the Douglas flat twin. Early in 1920, Stolle acquired a 1914-15 Model B 500cc Douglas and copied the motor to produce the M2 B15.

BMW R32

  • Stolle persuaded the Victoria Works in Nuremberg to fit the engine in its frame, creating the Victoria KR1. Positioned in the frame longitudinally as in the Douglas, with either belt or chain final drive, the M2 B15 also found its way into other motorcycles besides the Victoria, notably the Helios of BFW.

Further Reading 

The Complete Book of BMW Motorcycles:

www.murdochbooks.com.au

A site with some interesting background on the R32:

bmwdean.com/r32.htm

A great site for information on older BMWs:

www.bmbikes.co.uk

More information here:

www.bmw-classicbikes.com