But ambitions of Peder Fisker who was a leading engineer were much wider than manufacturing of household appliances. In 1919, the company, quite unexpectedly, has introduced its first bike Nimbus. The first model a prototype of which was designed two years before combined some promising features and stylish trends.
At first instance, your sight was arrested by the bike’s frame – thick-walled supporting pipe of large diameter masking a petrol tank. Similar solutions only just were coming into fashion in Germany. Two heavy-duty pressed bars formed the bottom part of the frame thus closing the contour. Between, a powertrain was located, which was an inline four-cylinder engine (746 cc, 9 h.p.) in a aluminium crankcase shared with a three-speed gearbox.
Cast-iron cylinders were casted independently. Valve train was designed as “valve over the valve”. Inlet valve drive was fully accessible and the pushrods went in pairs: two between the first and second cylinder and other two between the third and fourth cylinder.
Inline engine made conditions to implement a drive shaft because the rear wheel disk including the rear mudguard were suspended to the rear part of the frame using two springs.
The fork was complex and had two compression springs installed in enclosed casings. In this configuration (model A), bike had been manufacturing until 1923 when it was replaced by the B model, which had a simplified fork, an upgraded carburettor and a new intake manifold. In 1927, the manufacturing of the B model was ceased because the company wanted to expand output of the principal products.
In 1934, the Nimbus marque suddenly appeared once again. The design of the new machine only partially resembled the previous models that were equipped with inline engines and a driveshaft. For the rest, it was a whole new bike. Its double cradle was made only of pressed profiles that were very simple in shape.
The petrol tank was installed to the frame from above similar to BMW or Zündapp. The rear suspension was rigid and the front fork was telescopic with springs inside the pipe legs. The handle bar was a pressed plate at the end of which control levers were affixed; in the center, instruments and electric equipment switch were placed. Under the handle bar, a headlight was installed on the fork’s bottom bridge.
The powertrain needs a detailed description. It was an inline four-cylinder overhead valve engine (746 cc, 22 h.p.). Cast-iron cylinders were casted together with the crankcase top half as an integral part. The bottom half was made of aluminium and hosted an oil tank.
The removable cast-iron head of the cylinder barrel contained a camshaft covered with a special aluminium cover. The camshaft was driven by a vertical shaft, which was located in the engine’s front end; an electric generator with an automobile timer-distributor was vertically fitted over the front tailshaft.
Valves equipped with spiral springs were set in the V-configuration. Four valve rockers went out of the camshaft cover via individual openings on either side. So, rocker-valve pairs were accessible (opened). This was good for valve clearance adjustment, but as for the valve train, it reduced its service life despite the force-feed lubrication system. Another interesting feature of the engine was a forced ventilation of the crankcase via a carburettor.
A three-speed gearbox had a cunning gearshift control that allowed both a hand lever and a foot pedal (which was installed to the Luxus version since 1935) to be connected to the gear shift gate.
Moreover, the gear shift lever could be installed from either side at customer’s option. Rear brake foot pedal could also be installed on either side. A kickstarter pedal was an exception – it was located only on the left and went under the frame.
In 1936, the fork was reinforced, and the wheels got heavy-duty hubs. The bike could achieve 110 km/h having 172 kgs of its weight. In this configuration, bike was being produced till the end of 1940s when it was upgraded the last time.
The fork was a little modified, the headlight moved from the fork’s bottom bridge to special side brackets under the handle bar, the saddle was suspended on the jacketed central springs (instead of accessible springs on either side) and was equipped with rubber loops serving as arresters.
In this configuration the bike was being manufactured until 1958 when the manufacturing was completely ceased. According to some reports, it happened earlier, in 1954; and till 1958, the company had been manufacturing only spare parts.
Nimbus bikes circulated both as solo machines and with a sidecar. They had been selling to individual persons, to the Army, to the police and had been exporting abroad. In the history of motorcycles, the Nimbus probably is the only bike that was being manufactured without any modifications for more than 20 years.
|Manufacturer||Fisker and Nielsen, Denmark|
|Years of manufacture||1934-1958|
|Quantity produced, units||Over 12 000|
|Стоимость в современных ценах||N/A|
|ENGINE AND TRANSMISSION|
|Engine capacity, cc||746|
|Bore and stroke, mm||60 х 66|
|Engine rating||22 hp at 4500 rpm|
|FRAME AND WHEELBASE|
|Frame type||Duplex (stamped steel)|
|Wheel size||3,50 х 19|
|Ground clearance, mm||
|Seat height, mm||
|Gas tank size, l||
|Maximum speed, km/h||