Biographical elements in the great article by Claude Genzling / Source: LE CYCLE – N°47 of June 1979

The Great Places for Custom Bicycles – Depierre, Paris, Place d’Italie

There is a myth of custom-made bicycles. In many bike shops that display this label on their storefront, you often find only ready-to-ride options. A quick glance at the customer, and the oracle speaks: “You need a 56…” At Depierre, who manufactures the frames of the bikes he assembles himself, custom-made bicycles are a reality. No “Gemini” bike leaves his workshop without being designed and built for a specific customer. Among the famous road cyclists who entrusted him with making a frame to their measurements, we can mention Luis Ocana, Bernard Thévenet, Cyrille Guimard, José Catiau, Leif Mortensen, Raymond Delisle, and Régis Ovion, when he became the world amateur champion. And for the track, you can find Daniel Morelon, Pierre Trentin, Gérard Quintyn, and Alex Pontet. These are references that speak for themselves.

With the revival of cycling, you have certainly experienced the congestion in ordering, delivery, adjustment, and repair at various bike shops known in their neighborhoods and more or less specialized in high-quality bicycles. On Saturdays, groups of enthusiasts besiege the “specialist” and discuss gear ratios in the back room while a young boy comes in to get his moped tuned or buy a two-stroke mixture bottle. It’s a friendly atmosphere because it brings together novices, beginners, experienced cyclists, and riders of all kinds. At Depierre, on Rue Vandrezanne, not far from Place d’Italie, the atmosphere is entirely different. In the first room, Henri Depierre is often seen adjusting tubes, brazing, or filing a joint. This is where he constructs his frames with slow and precise movements that don’t encourage idle chatter from visitors. In the second room, just as small as the first but always immaculate, his son Jacques assembles a bike or repairs one for a loyal customer. And his wife laces or tensions the spokes of a wheel. Around them, never more than two or three “outsiders.” The dialogues are those of connoisseurs. They know gear ratios. They have tried the equipment. No, in the utmost calm, they simply exchange some gossip about the latest races, the ones they have just competed in or seen on television.

Henri Depierre began working for a bicycle manufacturer in Le Tréport at the age of fifteen. Already at that time, he was interested in racing frames and made a few of them at home, thanks to the guidance of a specialized craftsman who had worked for a reputable frame builder. From 1940 to 1946, he participated in races as an amateur and moved to Paris, providing custom frames for several frame manufacturers. Then came the crisis of the 1950s for bicycles, caused by the success of mopeds and the growth of the automobile. After a few months at Arliguie, where he set up a workshop, Henri Depierre changed his occupation and started making… lamps. In 1967, when his son had completed his military service, he decided to launch himself as an independent artisan-builder. The seriousness of his design and manufacturing methods and the new resurgence of cycling ensured the success of his enterprise.

The Frame Design

Henri Depierre believes that the best way to create beautiful frames is to love your craft and continually improve yourself. A recipe that’s as good as any. However, it is necessary to study optimal dimensions and find a style. That’s what he did, “in the manner of Chapman for Lotus”, as one of his friends likes to repeat. What does the “Gemini” style consist of? It is based on two simple ideas:

– The angle of the seat tube primarily depends on the length of the femur and does not simply vary with the frame’s height.

– The design of the steering is absolutely critical for a bike’s stability during descents.

For this second point, the “Depierre” line has resolutely deviated from the Italian cut, often characterized by a rather straightened direction. The steering angle of Gimondi’s bike, for example, exceeded 75°. Gemini bikes have a head angle that varies around 72°. Their trail is large, and can exceed 7, even for a road bike, the fork rake generally being of 3 cm. This is the opportunity to destroy a myth: when the trail exceeds 6 cm, we have no impression that the front wheel is guided “as if by a rail” and the curves are taken without problem. Bernard Hinault also won the Tour de France with a bike with a trail of 6.8 cm. It was with a bike whose frame Depierre had designed and built that Ocana won the Tour de France in 1973, the year in which he did not fall. It must also be admitted that the bikes of most French professional teams today resemble Gemini bikes like brothers, at least for the design of the steering. Steering that has a little design secret: the steering tube and the tube that connects the to the bottom bracket shell lug determine an angle that is studied in the same way as the steering angle itself, to ensure the best rigidity . For the inclination of the seat tube, Depierre simply applies the rule given by Daniel Clément: a plumb line passing behind the ball joint must fall on the pedal axle, when the crank is horizontal. The saddle, centered on the seat tube, must be compatible with this position. Generally speaking, Henri Depierre does not like being sent dimensions, even morphological ones: for him, a bicycle cannot be designed by correspondence, you have to see the user, preferably with a bicycle on which he has already made efforts. Because it gives valuable information, and he could therefore correct this or that defect.

The manufacture of the frame:

The emphasis is placed on the rigidity of the frame and the conservation of the mechanical qualities of the tubes which compose it. Rigidity is indeed essential, especially with the use of large gear ratios and the increasing number of riders with an athletic build. Henri Depierre practically only builds his frames with 6/10th tubes, for this reason. Fans of lightness, according to him, must choose parts and accessories accordingly, but above all not sacrifice the rigidity of the frame. For the same purpose, the tubes are cut according to the exact configuration of the connections, for the assemblies on the head tube and the bottom bracket: the tubes follow the design of these two parts, and are welded over the entire surface of the connection. This work takes time and cannot be done by a frame maker who wants to produce a lot. Brazing is done with “brass” and not with silver. This alloy holds heat well and does not burn. It should remain yellow after cooling, if it comes back red it means it has burned, which must absolutely be avoided. The connections are heated alone, with a small torch, and point by point. The flame is never directed onto the tube. With these precautions, which require particular care, the tubes retain most of their mechanical properties and give the frame its rigidity and its performance under effort. The connections, whose design reinforces the rigidity of the assemblies, are then filed and clothed, a job that is almost no longer done anywhere. Finally, the fork steerer, the head tube and the bottom bracket shell are milled and surfaced so that the mounting of the bearings takes place in the best conditions. To summarize, let’s say that all the operations which are usually shared between the frame builder and the bicycle dealer who assembles the machine are carried out entirely by Henri Depierre, which facilitates quality control.

Impressions of a “Geminist”: Among the few bikes I have, I have used the Gemini for over a year, and I must say that I am perfectly satisfied with it. At the beginning, I sometimes preferred a slightly lighter bike for racing, especially when there was some climbing. Little by little, I learned to perceive the advantages of greater rigidity, and the thin tube frame appeals to me much less, even for climbing: on the coast, when I went down with the Renault-Gitane, it is the Gemini bike that I took with me.”