The result of diversification by the Danish vacuum cleaner manufacturer, Fisker & Nielsen, the Nimbus motorcycle first appeared in 1919. Unusually, only inline four-cylinder models were built. The early models featured a distinctive tubular spine frame that doubled as the fuel tank, soon gaining the nickname ‘stovepipe’.
The low-compression Nimbus engine was noted for its smoothness and flexibility. In 1928, motorcycle production was suspended to enable the company to concentrate on producing its Nilfisk vacuum cleaners, and when the new Nimbus appeared in 1934 it was with a power unit that showed strong motor-industry influence, being constructed along car lines with integral crankcase/cylinder block in cast iron and a detachable alloy sump.
The cast-iron one-piece cylinder head was topped by an alloy housing for the single overhead camshaft, which was driven by shaft-and-bevel gears. A single-plate clutch transmitted power to the three-speed gearbox. The original ‘stovepipe’ frame had been superseded by one made from flat spring steel, while foot change for the gearbox, a beefier front fork, and larger brakes had been added by the end of the 1930s.
Nimbus was ahead of its time in many ways, introducing its first telescopic front fork in 1934 and adopting closed-circuit crankcase ventilation many years before the automobile industry. From then onwards the Nimbus changed little until series production was ended in 1954, once again to free up resources for the vacuum cleaner business. This Nimbus has been restored recently to a high standard and is in great shape. It runs fine./classic-motorcycle.com