Long before Vitus began making bonded aluminum frames (Vitus 979), the company had an extensive history of manufacturing quality steel bicycle tubes. According to Classic Rendezvous, Vitus began as Ateliers de la Rive, on the outskirts of St. Etienne, a city southeast of Paris, near Lyon. Beginning in 1931, they began making tubes branded as Rubis and Durifort.
These 1947 ads, which appeared in Le Cycle and Le Cycliste magazines, show that Durifort tubing was the brand promoted by the Ateliers de la Rive company as the company’s best offerings. Numerous races were won, with bicycles using the Durifort tubing. At this time, Rubis tubing was also offered, and was featured on a number of bicycles offered by the manufacturers of the day.
By the 1970’s, Vitus was making a variety of tubesets with different wall thicknesses, both butted and straight gauge.
I have owned and worked on several bicycles with Vitus tubing, the oldest of which is a 1947 Peugeot Mixte which featured Vitus Rubis tubing. I still have this bike in my collection. Although I have seen examples of Vitus’ bonded aluminum frames, I have not ridden one. I understand that these frames have similar flex characteristics to the alumiminum ALAN frames, which feature aluminum tubes screwed and glued into steel lugs, but Vitus 979 frames do not include steel lugs.
It would be nice to have a resource which identifies the characteristics of each designation of Vitus steel tubing, but this seems to exist only in fragments on various websites.
A writer called vertkyg on the gitaneusa.com forum has developed a fairly complete Vitus timeline, with interesting photos and commentary. He derived much of his information from a 1974 version of DeLong’s Guide to Bicycles and Bicycling. As I didn’t have this book in my collection, I ordered a copy and found it to provide a wealth of information, as well as being an interesting commentary on the bicycle industry of the mid 1970’s.
The top photo above shows that Vitus tubing in 1974 was offered as the following tubesets: 172, 971, and Durifort. Durifort was a butted set, but was otherwise identical to the 172 tubeset (although by this chart, I think both tubesets were butted). 971 tubing was presumably the best offering of the time, with its lighter weight .9/.6 wall thicknesses for all of the main tubes.
This additional chart shows the properties of various tubing offerings of the era. Vitus 971 tubing is shown to have ultimate psi strength in excess of Reynolds 531, and as you can see from the above chart is significantly stronger than lower end steel tubing of this era. It is much stronger than the Titanium B 338 tubeset noted on the table, and greatly so, as is Reynolds 531, of course. Vitus 971 and Reynolds 531 tubesets show similar performance characteristics, and could certainly be seen as equals in the marketplace at this time.
My early 1980’s Meral features this steel Vitus 788 tubeset. Available catalogues from this era do not feature this designation. From what I can surmise, this was apparently a butted tubeset with a 7/10 top tube, and 8/10 down and seat tubes, thus the 788 designation. Whether I am right or wrong about that, one thing I know is that Vitus steel tubing is competitive with the Reynolds and Tange tubesets of this era.
UPDATE 10/21/17: Reader Bruno (see comment below) has shared a different timeline of the Vitus, Durifort, and Rubis tubing brands and their related owners. It appears that all of these brands were initially owned by separate companies, and that Durifort was folded under the Vitus brand in the early 1970’s. The link he shares has many historical advertisements – if you don’t speak French you can use a translate tool to study the material presented there, which includes an article written by Daniel Rebour which reviews the history of Vitus.