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.

Old Bike Australasia - - CONTENTS - Story Jim Scaysbrook and Lars Glerup Pho­tos In­de­pen­dent Ob­ser­va­tions, James Jubb, Antony Gul­lick, Gaven Dall’Osto, Michael An­drews.

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.

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.