As already identified by eagle-eyed members of the List, Carlos was a Belgian company. It was only quite a small operation based at 33, rue Centrale, Maurage, and owned by Ets Harvent, who was also a wholesaler. In the early 80s Cycles Carlos advertised for a dsitributor in France and subsequently signed up with a chap called Remacle, based in the beautiful little town of St Cyr sur Loire, just outside Tours. Not far from down theLoire valley and slightly north of it, about 25 kms was the factory of the former bike-builder, Meral, based at Aubigne-Racan and Fuye/Homme. A certain Denis Quillon, now one of the guiding lights of the French cycle industry, and the founder/owner of the CYFAC company, was the foreman builder for Meral. When Meral finally uprooted further north, nearer Le Mans, Denis stayed put, and with a phenomenal output supplied frames to all manner of shops under a wide variety of names. Amongst the riders who are reckoned to have used his frames are Fignon, Hinault and the rest... when at Renault Elf.
I used to spend a lot of holidays in the Tours area and saw a good number of Carlos frames frames. Generally they were extremely well built and beautifully finished. A speciality was the bronze-welded lugless frame, the technique being used to build both solo and tandem frames. They were as well constructed as almost anything I have seen..certainly the work of a fine craftsman/men.
It would be reasonable to assume that the proximity of Carlos(France) to Quillon led to a liaison between the two companies, but I dont think this was the case. Quillon also built ... and in the early years of his independence from Meral..was kept afloat by orders from Jean-Marie Duret, for his "GELIANO" range, Duret being based further to the east in the Loire valley, but only a couple of hours away.
Quillon was also very much in the Bernard Carre school of frame-building, concentrating essentially on lugged frames, built with a technique that produced a frame that needed very little post-brazing cleaning up, was not a work of art, but that handled well. When enamelled by Duret's tame sprayman Quillon's frames looked ".a thousand bucks" if you will pardon the phrase. Jean-Marie Duret reckons that Ernesto Colnago got the inspiration for his Deco frames from the Gelianos displayed at the 1983 Paris Show. Certainly Italians from a number of top frame-shops were like a rash spreading over the GELIANO stand with cameras at the ready.
However I don't think, but am pretty sure that Quillon did not build the Carlos frames, but that they were the product of a Paris-based company called CACEG, who were sub-contractors to the French lightweight cycle industry and who turned out some stunning frames from their workshop at Montreuil just across the other side of the eastern peripherique.
But CACEG also preferred to use lugs..but not exclusively. However just up the road out of Tours, also on the Loire is the beautiful city of Blois. There, for a long time a very skilfull builder called Philippe has been producing elegant frames..and still does so..many of which are lugless. The lugless Maxisport frames used by the Castorama team in the early 90s are attributed to him.
So my bet is that some Carlos frames came from CACEG, perhaps some from Quillon..but that the lugless solos and tandems came from Philippe..unless of course they were built by the retired coppersmith, that wizard of the torch, Bebere..he never seemd to have another name..who built wondrously elegant lugless frames for Duret/Geliano. It was Bebere's lugless frames for Geliano, displayed at the 1985 Milan Show, that inspired Francesco Moser to introduce similarly built frames into his range. And to do so he chose a French builder...but none of the ones mentioned. Instead he turned to Andre Sabliere, of Lyon, to produce his prototype range.
So your guess is as good as mine.
Norris Lockley...Settle, UK