There were several manufacturers of frames such as this one in France in th e late 40s - Mecadural, AVIAC, Gnome et Rhone for starters, all of them in one way or another involved in the aitcraft industry. It is not surprising therefore that they all produced frames using assembly techniques that had been used in aircraft.
The MecaDural appears to be held together by a mixture of techniques such a s bonding, clamping and expansion joints ie the rear drop-outs and some oth er jloints are bonded, the chainstays are clamped to the bottom bracket, bu t the head-tube, top-tube and down-tube joints are held by expansion bolts. All frames of this manufacture always have two head badges
If the head badges are removed two holes appear...inside the holes screwed devices can be seen. I have never dissembled one of these frames but assume that there are expansion cones/wedges inside the joint that force the oust sides of the tubes against the inside of the head-tube lugs, in the same wa y that an expander bolt handlebar stem works.. It is quite possible that so me form of bonding/adhesive agent was also used, bearing in mind that in WW II the British Spitfire fighter planes had many bonded joints...phenols, ha ve been suggested.
In the early 90s a similar form of construction was used by both TANGE and TVT when assembling the bottom bracket joints of their frames, but in those cases an epoxy bonding compound was used.
MECADURAL appears to have been a brand owned, or at lewast distributed sole ly by Ets Mercier, of St Etienne. The name Mercier never appeared on the fr ames, but others such as Francis Pelissier, Charles Pelissier, Andre Leducq , Antonin Magne and Archambaud, often graced the head-tubes and down tubes. Mercier owned the copyrights to all these and several others, including La pebie.
Thiis frame on Ebay appears to be breaking the price barrier for this type of frame, but there again it does have a Simplex derailleur, a good pair of brakes and interesting bars. The chainset on most of these bikes was a sin gle Stronglight Model A.
Gnome et Rhone produced frames that bonded ( or somehow fixed) steel tubes into alloy, or sometimes steel head-tube assemblies. The result was a neate r looking frame than the Mecadural. There is a matching pair of his and her Gnome et Rhone bikes in immaculate original condition near my house in France. I often see them parked outside supermarkets, but no matter how lon g I wait outside, I have yet to meet the owners.
The company had made a successful range of motorbikes and aeroplane engines , but in 1949 it was nationalised and formed into the still-existing SNECMA company that produces jet engines for a number of the Boeing range of plan es. The comapny has several massive factories quite near central Paris.
Norris Lockley...Settle UK