The placing up for sale on the List, by Hilary, of two aluminium frames, both badged as Merciers, has evidently casued a little confusion about the origin of their manufacture. It really was a tremendous coincidence that Hilary pulled both these aluminium rabbits out of the same hat on the same day..if you will pardon my mangled metaphors. And I am not very sure that my attempts to rise to Hilary's implied invitation to clarify the origin of the non-Mecadural frame helped the cause. It was almost a case of if you can't convince the Listers then confuse them....not at all what I intended. Jerry had been left wondering just what brand his exemplary aluminium bike is.
After the WWll, as with most wars, there was a washover of technical progress ie advances in engineering know-how and materials technology , that drifted into everyday life. One such gain forJoe Citizen and his family was the greater use of aluminium alloys. The cycle industry was one of the industries to profit extensively.
Three companies that had been involved in aerospace, if that is the correct word, during the War diversified into the cycle industry, the most prominent of which was Gnome et Rhone, the manufacturer of aeroplane engines.; this company developed a small range of lightweight frames incorporating three main aluminium alloy tubes into steel lugs and a steel rear triangle. Another firm involved in the war effort developed an all-aluminium alloy frame with curious, apparently crimped together ,tubes and cast lugs; this was called the AVIAC. A third firm developed a frame with cast aluminium alloy lugs into which were fixed the aluminium tubes - this frame was called the Mecadural.
As far as I have been able to discover the Mecadural was the brainchild of the Duravia company that appears to have hailed from just north of Lyon. I am still checking the facts on this matter, as it seems that some of the castings came from a firm in St Etienne, but the two cities are quite close.
Very little is known about AVIAC except that it was based in the northern suburbs of Paris. Gnome et Rhone became State owned, is now called SNECMA, and its products are mainly aircraft engines some of which are used in Boeing aircraft. The company has a large research facility. After WWll Gnome et Rhone concentrated also on the development of motor cycles with pedal cycles as an ancillary activity.
Most of the Mecadural frames that still exist carry either the Mercier brand or one of the company's sub-brands such as Francis Pelissier, Antonin Magne, Andre Leducq, and Lapebie, although, as in Jerry's case, some obviously carry the actual manufacturer's name. I have seen a lot of Mecadural frames and bikes but Jerrys' is the only one I know to have anodised lugs, so maybe that was a characteristic of the DURAVIA brand. Further north in France La Perle used Mecadural frames as did, to a lesser extent, Helyett.
All these three brands of aluminium frames, the AVIAC, the Gnome et Rhone, and the Mecadural have a comon characteristic in that the construction of the frame relied in part on mechanical fixings to secure the main tubes. All three frames had two badges on the head-tube. If these are removed, holes are revealed..the holes permitting access to the fixing systems that work like expansion bolts, holding the tube firm inside the lug. A similar system was employed several decades later by TVT and Tange to provide greater strength and grip in securing the down and seat tubes to the bottom brackets of their carbon frames. I am assuming that the name Mecadural was adopted to describe both the frame's material and its manner of construction.
AVIAC's frames appeared to use also some form of swaging or crimping of the tubes over the lugs..and, never having taken an AVIAC to pieces I am uncertain whether these frames had one hole in the head tube or two..certainly there were AVIACs with only one hole. AVIACs also appeared with brands such as Peugeot, but also bearing the headbadges of smaller shops. Perhaps there were the Duralinox 979 of the 40s.
Duravia, possibly due to the success of the Mecadural, went on to develop other more modern models such as the MERCIER -branded one sold by Hilary, the frame with the large cast lugs with external allen screw clamping devices. This could almost be seen as an updated Caminargent-type structure, in which no joints or fixings such as the drop-outs are internal.
There are certain parts on the Duravia that resemble or are identical to certain parts that appeared on another aluminium frame that appeared in the early 70s. I have seen several of these but they had no transfers or headbadges, possibly due to the industry's migration away from badges to transfers on head-tubes. These were made in or near Lyon. Another derivative appeared in the late 70s, called the CMP. This was the product of a firm based in Meribel, on the banks of the Rhone,a small town just outside of Lyon to the NE. These frames had features in common with the Duravia ,a coincidence that might be explained by the frames being manufactured by the same company or by the components and such things as the round fork blades being supplied by the same external suppliers such as Pechiney Possibly Duravia was bought out by the parent company of CMP. The CMP used alloy tubes passing inside cast alloy lugs, with a small cylindrical sleeve close to the entry point. Apparently at this point the lug and tube are somehow crimped together and the sleeve or ferrule covers the crimping. More research needs doing. It is interesting to note that the same CMP lugs, with very slight refinement to the seat lug were used on the early TCTs, that became TVTs, both brands being made just to the east of Lyon.
Possibly the last manifestation of the Mecadural,/AVIAC/Gnome et Rhone internal expanding joint type of construction was the HAUTIPROD frame that appeared in the mid-to-late 70s. This had a very modern angular appearance, but the whole of the frame relied upon mechanical fixings, with even the round fork blades using exposed allen-key expander bolts inserted down the fork crown. These frames were made in a small town just too the NW of Lyon.
One thing that I have not been brave enough to investigate is how on the AVIAC and on the Mecadural, the fork ends were fixed to the stays and fork blades. They look as though they have been bonded, and I have been told by a former aircraft engineer that as early as WWll, there were glues/bonding agents developed and used in the construction of aircraft fuselages and wings.
The nof course there was the MIOSOTTI..again made in the suburbs of...yes..Lyon.
Concerning Jerry's immaculate Duravia-Mecadural ( was it so shiney when you bought it or have you done it yourself?) it is the only frame of its type that I have seen with an alloy fork. I wonder if that is original..or did someone such as BARRA supply them specially.
Norris Lockley
Settle UK