Nimbus Danish treats
Honda has built over 100 million variants of the C100 Step Through. Yet in a manufacturing life of 40 years – from 1919 to 1959 – Nimbus built just 12,715 examples of their four-cylinder motorcycle. Less than one per day.
Perhaps that’s because its creator, or more correctly co-creator, Peder Andersen Fisker, was a technician who dabbled in engineering merely as a hobby. It was a collaboration with Hans Marius Nielsen, who also hailed from Copenhagen, Denmark, that led to a business venture in 1906 involving an electric motor the pair had built. That motor was refined and adapted to power the first European vacuum cleaner, the Nilfisk, which was produced from 1910 and which was patented by Fisker. Nilfisk is today a global identity in the cleaning business but by 1919, Fisker and Nielsen had a new venture going – a motorcycle.
This was no flimsy start, no bicycle-based motorised two-wheeler. The first Nimbus (named after the luminous clouds often depicted in illustrations of saints and other holy beings) used a 746cc four-cylinder engine with bore and stroke of 60mm x 66mm, shaft final drive, three-speed gearbox and a pressed steel welded frame with sprung suspension at both ends. A novel feature was the large diameter top frame tube which doubled as a petrol tank, leading to the nickname ‘stove pipe’. The Nimbus poked out about 10 horsepower with a top speed of approximately 85 km/h. To say production was slow is a major understatement – just two were completed during 1919 and ten the following year – but the buying public took a shine to the machine and demand encouraged the partners to embark on a redesigned model that was released in 1923. The update included a new type front fork and a more efficient carburettor. However Nimbus, and other manufacturers, was hard hit by the introduction of a sales tax on motorcycles in 1924 which severely flattened sales. At the same time, sales of the Nilfisk vacuum cleaner were going through the roof, and the decision was taken in 1928 to cease production of motorcycles after some 1,200 had been made. The vacuum cleaner business boomed to such an extent that a new factory was built.
Fisker wasn’t finished with motorcycles however, and he now had an empty factory at his disposal. Working with his son Anders, a new Nimbus was created in 1934, called the Type C. The basic specification remained, but the 746cc engine now had the valves actuated by an overhead camshaft. Like conventional car and aircraft engines, the upper half of the crankcase and the cylinders were cast in one, with the lower crankcase half being a an aluminium oil sump. The one-piece cylinder head incorporated an inlet manifold with exhaust valves on the right and inlets on the left, each automatically lubricated. An aluminium camshaft housing was bolted to the cylinder head, carrying ball and socket bearings for the rockers. At the front, the vertically-mounted camshaft formed the armature spindle for the dynamo, with the gear-type oil pump at the lower end. Coil ignition was used with automatic advance and retard, the contact breaker sitting in a casing bolted to the camshaft housing. The camshaft itself was a single drop forging running in two large diameter ball bearings. At the rear of the crank sat the flywheel which incorporated a single plate clutch. To this was bolted a three-speed gearbox which was hand-operated for the first two years of production, with an optional foot-change available from 1936. The drive shaft ran from the left side of the engine ‚
to the rear wheel. A piece of forward thinking that would later become quite commonplace was the funnelling of exhaust blow-back collected in the crankcase up to a chamber connected to the carburettor. As well as producing a cleaner running and more efficient engine, this also lowered crankcase pressure and eliminated (or perhaps reduced) leaks from oil being forced out through gasket joints. The frame was completely new; made from sections of flat steel, welded and riveted together, with the top tubes wrapping around the conventional petrol tank. Up front was a telescopic front fork (preceding BMW), although hydraulic damping was not incorporated until 1939. The rear end was rigid. Despite the four-cylinder engine, all-up weight was just 172kg. Fisker and son set up a strong dealer network for the new product and the Type C went on sale in mid-1934. It was soon nick-named the Bumblebee due to its distinctive humming exhaust note. Success was instantaneous and the Nimbus gained valuable sales through the Danish police, Post Office and eventually the army. With equally healthy civilian sales, the Nimbus quickly became the biggest selling motorcycle in Denmark. The basic Model C remained in production until the end, being subtly refined along the way. A heavier front fork came along in 1936, along with beefier brakes, in line with the machine’s favouritism as a sidecar hauler.
Series production concluded in 1954, but motorcycles continued to be assembled in small numbers until 1959, using accumulated spare parts. Military models accounted for almost 20 per cent of the total made in 40 years. As late as 1972 the Danish Post Office still ran the Nimbus, and the Danish Marine Force continued even longer. Very few Nimbus motorcycles were exported, although some were sold in Africa and a smaller number in America and eastern Europe. The majority of the 12,000-odd made are still in existence, thanks to the efficient spare parts supply.
Lars Glerup’s Nimbus with Acap sidecar on show in Brisbane.
ABOVE A Nimbus in the Solvang Motorcycle Museum, California. OPPOSITE The 1924 ‘Stovepipe’ Nimbus in the Motorcycle Mecca Collection, Invercargill, NZ.
Grant and Nicole Evans with their Nimbus outfit.