The Ivory Calthorpe is a well known vintage motorcycle that claimed its name from the distinctive colour scheme. At the time, most motorcycles favoured black palettes, and so the Ivory Calthorpe was a bold statement that went against the grain. But, in an ironic twist, did you know that the Ivory Calthorpe had another paint option? This is an Ivory (500cc) Calthorpe with the optional ebony black option paint scheme, and to start the story, here is quick synopsis of where it all started.
George W. Hands was a Birmingham bicycle maker and driven entrepreneur – and his company had a wonderful name – Hands and Cake, which would later become the Bard Cycle Manufacturing Company Ltd. The company was liquidated in 1902 and the following year Mr Hands founded the Minstrel Cycle Co. (to become the Minstrel and Rea Cycle Co. in 1906). The corporation would, until the end, become the “Calthorpe” owner as marque and various companies.
The Calthorpe Motor Co. was founded in 1908 and later converted into a Ltd company which built and sold the first official Calthorpe motorcycles. Calthorpe used outsourced engines in their assemblies (this was normal for many outfits of the era) and the first motorcycle in 1909 used a White and Poppe 3.5hp. This practice continued for many years, however by 1924 Calthorpe had developed their own motors in house, which included a 350cc pushrod engine and, in 1927, an overhead-cam 500cc unit. These developments of self-sufficiency provided the company with the power to expand and in 1928 Calthorpe introduced their new range – the Ivory Calthorpe, so called because of the distinctive cream finish to the fuel tank and mudguards,” which were a novel update from the dominant all-black colour schemes present across the industry.
There were a number of engine options available over the production years, all in overhead-valve form. The Ivory started out as a 350cc overhead-valve inclined engine with twin-port cylinder head, and then in 1932 a 250cc two-stroke was introduced (the Ivory Minor), in addition to a 494cc overhead-valve model (listed as the Ivory Major in 1933).
The Ivory gained immediate acclaim and received positive reviews from the Motor Cycling magazine:
“The two-port super model is entirely new and is certainly one of the most attractive machines in its class“.
It was also a well priced machine with the base model available for a mere £47-00 – possibly one of the cheapest enclosed OHV motorcycles at the time. Motor Cycling went on to report:
“Looked at as a complete motor cycle, there is evidence in its every line of thought and ingenuity behind it, while the quality of the workmanship and the equipment make it a force to be reckoned with in its own particular field“.
The test machine loaned out to the press was a hit, and it was praised for its handling, roadholding and mechanical silence. The machine was stable at speed, could be heeled into bends with purpose, and could thump along comfortably at walking pace. It was also a rather handsome machine, with a purposeful riders position, and was finished with large diameter exhaust pipes and distinctive fishtail silencers for that sporting look.
The 1936 Calthorpe 500 featured was unearthed in Ivory colours, but has been reintroduced to the road in the ‘ebony black’ option trim. It has undergone a meticulous transformation, and we will take you through a snapshot of the process with the help of owner Martin Bienek.
Let’s start with the advert from back in the day:
“Calthorpe offers you the best value for money in the British motorcycle industry”.
Well, in that case, what is not to like? And that was certainly the case for Martin, who became stuck in the same honey trap that has caught so many classic motorcycle connoisseurs… and for Martin, his chosen mount had to be a 500cc Ivory. It took some time scouring the ads of popular marketplaces until one day he fell upon a suitable candidate that was advertised by a UK based dealer. A deal was reached, and the motorcycle was shipped to Martin who then started the process of removing the meat from the bones, to see what he had really purchased!
The Calthorpe is an M4, which relates to the model and production run. Martin explains:
“The engine is an M4 (M = Major = 500cc, 4 = fourth generation). In comparison to its predecessors (M1 to M3), a lot had been updated. The bore and stroke remained at 85.5mm x 86mm, however the M4 has an oil circuit with a bypass valve and a reinforced cylinder with a wider outer diameter. The cylinder head has increased in size and what is particularly noticeable is the encapsulated valve train.”
The old proverb “what you don’t know won’t hurt you” is often one adopted by classic enthusiasts until that moment that the machine starts to rattle and smoke – then you stop and worry about what to do next. However, a motorcycle that has sat around for a number of years with unknown provenance really needs to be opened up and checked, and this is exactly what Martin did. The can of worms was officially opened.
“It was clear from the start that the machine needed to be restored from the ground up. The motorcycle had previously been restored, but in very bad form.”
The first step was the motor, which was pulled apart to reveal a labyrinth of problems, with a collection of worn, pitted and incorrect parts. If there is any positive that can be taken from this, a full rebuild really puts the owner in tune with the bike. Martin went into meticulous detail to have the motor rebuilt, and this process is well documented and detailed on his website (details of which are posted at the base of this article).
The M4 genre of Calthorpe features a four-speed Burman transmission, which at the time was marketed as a heavy-duty gearbox. There were many gearboxes that had not quite kept up with the increased demands of 1930’s motorcycles, but the robust Burman was more than capable, so much so that the same transmission was used on motorcycles for another three decades.
“The main shaft bushings on my gearbox were worn and had a play of 2,5 tenths of a millimetre. These were replaced and the entire gearbox was cleaned, checked and installed.”
As the motorcycle started to come back to life, Martin had the decision to make on the colour scheme.
“The brochure from 1936 reads: “Finished in Ivory and Black, or Black and Gold”. This sentence kept me busy until I took the prepared parts to the painter. On one hand, the Ivory colour provides the series with its name, however on the other hand, the colour black would make the motorcycle even more special and would certainly strike up one or two conversations. I have pictures of a machine in the original black and gold paint, and so I decided on the Black Option.”
As shown in the photos, the result is spectacular and really adds a special touch to the machine, however the restoration process was still very much under way. The next focus was on the wheels, which were completely dismantled, stripped and rebuilt from scratch.
“During a previous restoration, the bike was sandblasted and painted as a whole. This made it difficult to loosen the nipples. The individual parts were stripped of paint and cleaned which revealed the Dunlop embossing on the rims. After initially building the wheels completely in black, I decided to go with chrome-plated spokes.”
If you have ever had the trying task of replacing a tyre on a motorcycle, then you may well relate to the next part…
“Putting the tyres on is very laborious without damaging the rim. Nothing works without rim protectors! Powder, dishwashing liquid and three tyre irons (500mm) were used as aids.”
The frame as a whole was in solid order, as were the forks which were manufactured in house by Calthorpe and said to be based on a Druid patent. The thinner sections of sheet metal on the bike however had been nibbled by the rust monsters.
“Unfortunately, the old mudguards could no longer be used as there were more holes than material, but were still ok to use as templates for reproduction ones. The rear mudguard is divided into two parts to enable the rear wheel to be removed when the machine is elevated.”
The crux of the bike was there, and it was now the finishing touches to sort. As can be seen in the first photo in this article, the seat was in poor shape, and so Martin went the extra mile to source a correct replacement.
“I purchased a replacement saddle online. The old saddle was too small and too badly corroded and broken to be repaired. I bought an original Terry saddle in England. This was unused and in great condition for its age! I completely dismantled it and refurbished it. The faux leather blanket was separated and re-sewn because old threads had come apart. The horsehair upholstery was also renewed for the same reason. The springs and rivets were replaced and the saddle frame was painted. Calthorpe has always used Terry saddles. I decided on a “Big” Terry. This measures 15 inches in width and is therefore very comfortable!”
“The restored electrical components were built and wired to the motorcycle. I pulled the cables into a fabric-covered grommet and then laid them with rubber cable ties, as were common at the time.
After two and a half years of restoration, I completed the first test-and-adjustment drives. It runs great but needs adjustments here and there. Of course, I can’t drive on the roads with the English license plates. Road approval is the final step!”
The Ivory Calthorpe was never marketed to be a prowling monster born from the track. It was instead a well built bike that could cover all bases, at a reasonable price, and for this reason it proved to be a popular mount, and for good reason. As shown in the photos in this article, it is all one hell of a handsome machine.
This article details only a snippet of the graft that was put into the restoration of this lovely old Calthorpe. For a more detailed step-by-step account, head over to calthorpe.org.
Thank you to Martin Bienek for his input into the article and for the the use of the photos and content.
an article by The Girder Club
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