NIMBUS TYPE C...........................................
Always one to be totally in tune with modern trends, Ace Tester Miles presents what might be the ultimate in Danish hygge. A cosy motorcycle? Whatever next?
Always one to be totally in tune with modern trends, Ace Tester Miles presents what might be the ultimate in Danish hygge. A cosy motorcycle? Whatever next?
Winding his window down to speak to me, the van driver remarked ‘Your vintage scooter goes really well. What is it, a 125?’ I told him the capacity. He looked very confused before adding ‘It’s a bit rubbish for a 750 then mate’.
In a nutshell, this brief exchange sums up the incredible contradiction that is the Nimbus motorcycle. Built by the celebrated Danish electrical motor and vacuum cleaner manufacturers ( among other things) Fisker and
Nielson, the four cylinder machine first saw light of day in 1919. The earliest models had a large diameter ‘spine’ containing the fuel and are known today as the Stovepipe machines. Updated in 1934, the Nimbus Type C remained virtually unchanged until the company ceased motorcycle manufacture completely in 1959, having made about 12,000 examples. The fact it was essentially unaltered for such a long period of time is important and something we’ll return to later.
The 185kg, 18 or 22bhp Nimbus was powered by an inline four cylinder ohc motor of 750cc capacity. The motor utilised a car-type distributor and all the electrics were bespoke items, designed in house by F&N themselves. That’s the first conundrum. How could such a technically advanced engine of three quarters of a litre capacity and made with four cylinders be so puny? In the power struggle it would barely match a contemporary 350 single from one of the British manufacturers. The frame itself is predominately
a series of flat steel lengths that are riveted together, with some slightly more complex metal pressings completing the design, such as the integrated top yoke/ handlebars. The Nimbus had telescopic forks, nothing unusual by the 1950s but they appeared on the earliest models, too, pre- dating BMW by several months to claim a world first. It even has an ignition key, as well as lights operated by a rotating left twistgrip.
Although a rigid design with no rear suspension, rider comfort is enhanced courtesy of thick rubber bands that dampen the worst of the road shocks by isolating the saddles. These are available in different grades to compliment the, ahh, variable mass of the rider’s bottom. Power is transmitted via a three-speed gearbox to a shaft drive and was made with either solo or sidecar gearing. Despite this example being the posh deluxe version, there is virtually no chrome plating on the Nimbus. Almost every surface is adorned with thick layers of paint, including the silver-painted wheels. The Nimbus looks tiny and far too flimsy to be a 750cc four and, although it’s obviously a motorcycle, the styling cues seem just plain wrong for anyone used to a mainstream bike.
Starting is simple: key turned to ON, confirmed by a red lamp, twist the throttle a couple of times to prime the accelerator pump on the carburettor, then just one press of the slightly awkward lever is usually enough to set the four pots chattering. I must report that starting the Nimbus never failed to gather a small crowd, and watching the exposed valves opening and closing was a constant delight and the cause of much merriment among the gathered throng. Revving the engine produces a distinct buzzing sound and Nimbus owners affectionately refer to them as bumblebees.
Using the featherweight clutch and clunking into first, the little bike buzzed away happily. Second and then top gear quickly follow suit, and at lower speeds the throttle response is lively and delightful. At higher speeds… erm,
there are no higher speeds; twenty two horses and leisurely gearing are sufficient to propel the Nimbus to about 50mph and very little more without thrashing the daylights off it.
Once in top gear and accepting your fate of not going anywhere very quickly, the Nimbus proves itself to be a very capable motorcycle. The vaguely Heath Robinson rubber suspension loops work perfectly in conjunction with the oil-damped telescopic forks and the ride is both comfortable and sufficiently taut – for a slow bike.
The electrics were faultless throughout my time with the small Dane. The twistgrip lighting control, charging and ignition were both efficient and as perfectly designed as you might expect from a company specialising in electrical products. And motorcycles.
When it was first released back in the 1930s, a four cylinder motor would have been almost exclusively deployed in a car. Unlike most motorcycle power units of the time, the Nimbus 750 is a four-wheels familiar, wet sump design, which remained impressively oil tight throughout the test. The strange pipe you may spot running down from the carburettor air cleaner is in fact a springloaded oil filler cap of prodigious dimensions. Never has a bike engine been easier to fill, yet I used no 30W oil during the test.
I know what you’re thinking! I did, too. Surely, it must be possible to improve on the weedy power output? Twenty two horses is just pathetic from a 750/4 – and this is the sporting model! Yes and no, seems to be the answer. For sure, the miniscule carburettor with a choke size similar to a UK pound coin might be swapped out for a larger unit, or even twin carbs if you want to go crazy. You’d need to get the head gas flowed and a hotter camshaft to allow it to rev harder, of course, but, oh, there’s another issue.
The long crankshaft is supported by only two, admittedly huge, main bearings, one at each end. Rev this too hard and the centre of the crank might flex with alarming consequences. Finally, even assuming that you’re prepared to accept the risk of an engine failure by tuning it for speed, there’s still the small matter of the gearbox and final drive, both wholly unsuited to sporting use. No, if you own a Nimbus you have to acknowledge and embrace both its weirdness and its limitations.
I’ve read several ‘tests’ of these motorcycles over the years and, almost without fail the author ends up describing them as utility or budget bikes, referencing their use by the Danish military and post office, the implication being that they are too poorly developed to compete with proper bikes, whatever they are. I disagree completely with that assessment, thinking rather that they are one of the most completely integrated designs I’ve ever seen or ridden.
Designed for use in a land where distances were large and weather conditions inclement, Nilfisk made a bike that was rugged and weather-tight. Their design suggested a lightweight four would be less stressed than a single of similar power output, so would be smoother and more reliable, hardly the actions of a company working to a tight budget. The flat section frame was simpler to make than a welded up series of tubes, and in any case they were familiar with that style of manufacture – and rubber bands can be made to work as well as springs. Why use expensive plating on cycle parts that will corrode in the Danish winter? Far better to paint everything instead. And so on. Their logical thinking appears well founded, as nearly three-quarters of all Nimbuses ever made are thought to have survived, and they tend to be ridden rather than hidden in collections.
The Nimbus Type C was built to a very specific brief and it fulfils it brilliantly. Further development wasn’t ignored, it was largely unnecessary. The bike was perfect for its task. If it seems too slow for a 750, or just a little too weird with that angleiron frame, that’s your problem and not the bike’s. If you rode the Nimbus only at sensible speeds, perhaps around town or on short journeys, the performance would be entirely adequate. I used it for commuting in heavy London traffic and it proved as practical as a modern 125.
Always starting easily and with impeccable manners, it would easily suffice as daily transport. Perhaps the sort of thing a postperson might use; who knows? My only real issue was the outright lack of speed, which prevented me from making the sort of progress I really enjoy when out riding. But again, I fully acknowledge that’s my problem, not a fault with the Nimbus. So, is it the weirdest bike ever made, or the best?
You tell me.