1905 Magnat Debon ‘Modele G’ 3-Vitesse (dans le pédalier)

Magnat Debon was one of the most innovative of the early French cycle manufacturers, pioneering speed gears in the bottom bracket before hub gears had been fully developed. Observe the top tube mounted gear trigger disc, pictured below, which rotates to locate the gear.

The Sturmey Archer three speed, introduced after the Magnat Debon, used the key ‘High, Medium & Low’ on its gear trigger. The key on the Magnat Debon trigger is far more charming…

P = petite

M = moyenne

G = grande

1905 Magnat Debon ‘Modele G’ 

Velo a changement de vitesses dans le pédalier

(Three-speed Gear in the Bottom Bracket)

24″ Frame

26″ Wheels with Hutchinson 650 x 42B Tyres

(Now sold)








Watchmaker and inventor Joseph Séraphin MAGNAT and mechanical engineer Louis Auguste DEBON formed their company in Grenoble around 1892 to build bicycles. They patented numerous cycle innovations for brakes and gears, and for  a ‘balanced and anti-vibration’ engine in 1899. The earliest patent I found for Joseph Magnat was for an automatic beer pump operated by water pressure, in 1889. His 1896 patent registered a design for a front brake inside the steering head (below), an idea subsequently used on French bicycles.

Joseph Magnat developed a carburettor in 1901 and their first motorcycle appeared in 1902, equipped with a 250cc de Dion Bouton engine, and known as an ‘Autocyclette’. After Swiss engineer Arthur MOSER joined the company, Magnat Debon produced motorcycles with their own engines (from 1905). Its 400cc motorcycle known as the Magnat Debon ‘400 Aviation’ was used extensively during World War 1 by the French cavalry (the name relates to the use of observation balloons). But the surplus of American Harley Davidson motorcycles left behind in France after the war caused serious difficulties for motorcycle manufacturers, and Magnat Debon stopped production in 1920. Terrot was expanding at this time, and in 1921 purchased Magnat Debon.

Magnat Debon specialised in bicycles with innovative gears. From 1902, they offered both the retro-directe system and two or three speed gears in the bottom bracket, and the company’s top bicycle models featured a combination of both. The Model F two speed and Model G three speed was produced until the company’s demise in 1920.