The Spirax Derailleur

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Raymond Bon was one of René Herse’s team riders. In the late 1940’s he designed the Spirax derailleur, seemingly quite a revolutionary gear. The main principle of the design was to maintain even chain tension throughout the gears.

One of the disadvantages of the Cyclo gear, as used by most touring cyclists of the period, was that chain tension was uneven, being maintained only by the long spring attached between the derailleur and a lug on the chainstay. The Cyclo also had a ‘dual’ cable arrangement which is a little tricky to set up. Bon did away with both these disadvantages in his design. The gear still moved along a rod with a helical groove, like the Cyclo, but the visible flat coiled spring returned the gear along the rod using its tension. This meant that only a single cable was needed for actuation. There was a second coiled flat spring concealed inside the metal casing, which maintained the chain tension.

It could handle a wide range of gear and chain-wheel sizes, 12 teeth at the rear and 20 teeth at the front. The lever was ‘indexed’ by virtue of a captive ball bearing clicking into the holes in the drilled washer as illustrated in the drawing by Daniel Rebour below. It was also said that the gear could handle a six speed rear block, making it possibly the first six speed gear.

It appears that the gear was available from about 1950 to 1956. Despite the theoretically sophisticated and revolutionary design, it is rarely seen fitted to bicycles of the period. You can see one on a Herse dating from 1950 on pages 156/7 of Jan Heine’s book on René Herse, and also to my Goëland below. So why was it not a great success? I can only assume that in practice it perhaps didn’t live up to expectations. At present I am having difficulty getting enough chain tension on my one!

Do any readers have recollections of this gear and can they perhaps can shed some light on its shortcomings?

Photo’s of NOS Spirax gear reproduced with the kind permission of Chris Protopapas.

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Goëland Special Randonneur c.1950 with Spirax Derailleur

The Paris constructeur Louis Moire was quite a prolific maker, from the mid 1930’s to the early 1970’s, under the Goëland (Seagull) name. From his shop at 44 Rue Etienne Marcel, he retailed mid-priced machines which were probably often made by outside frame builders. He seemed to like ‘Speedy’ tubing, a heavy duty cheaper product than the finer productions of Reynolds or Vitus. I’ve seen many Goëland bicycles, and they are often handsomely finished, but rather heavy and fitted with mid-range parts. Occasionally he produced special bicycles in top of the range Vitus or Reynolds tubing, fitted with the best parts and many hand made fittings. This is an example of such a machine.

Constructed in Reynolds 531, the frame has heavily modified and finely filed Oscar Egg (or possibly Nervex?) lugs. Goëland-made parts include front and rear racks, front derailleur and handlebar stem. Rear brake cable and dynamo wiring runs internally. The rear brake hanger arrangement is unusual with the cable looping around a neat alloy hanger and back up to the fitting beneath the saddle. Brakes are M.A.F.A.C. cantilevers with the early open-back levers. Rims are early Super Champion laced to Maxi-CAR hubs, fitted with rare Cyclo ‘Rapid’ quick releases. Mudguards are Lefol ‘Le Paon’. Chainset is Stronglight, with Tank pedals, and Tank 4-speed freewheel. Handlebars are Phillipe randonneur and the saddle an Ideale 59 Professionel. The most interesting fitting, though, is the Spirax rear derailleur. This remarkable and rare derailleur was designed by Raymond Bon in the late 1940’s. Bon was one of René Herse’s team riders. It works on a similar principle to the Cyclo, with the sprockets sliding along a rod with a spiral groove, but it has a single cable and a built-in spiral flat spring, which keeps the chain in tension much more evenly than the chainstay spring on a Cyclo. The gear is also ‘indexed’, the changer incorporating a ball bearing which clicks into place at each gear change. More about this gear in a later post (Does anyone have further information about setting up this gear?)

The bicycle is in excellent original order. The only non-original part being the rear lamp. The original rear lamp appears to have been fitted to the left rear chainstay, as there is a lug and wiring there. The transfers are in reasonable condition, whilst there is extensive light blue lining, beautiful executed.

I will be carrying out minimal work to the bike, touching in a little of the missing enamel, and replacing cables and handlebar tape. One unusual feature of the bike is a rather jazzy colour scheme. The lining is pale blue, whilst the dynamo wiring and brake cables are green, and the brake hoods are red! The little windows in the head lugs are also filled with green paint. This is quite an unusual colour scheme and I intend to keep it like that. I have yet to find green cable outers similar to the disintegrating originals, and red second-hand mafac hoods (anybody got some?), so it may temporarily be finished with light blue bar tape and cable outers until I find the correct parts.

So, here are some pictures of the bike in its as-found state, with more to follow in a later post.

More pictures of Goëland machines here.

Click on photo for large-scale image