Hi David,
Super Vitus 980 is a very fine material and was manufactured by Ateliers
De La Rive, of Charmond, France, we know them as Vitus. SV980 was
introduced in 1984 and was coded by Vitus as 18M5 and is similar to if not
the same as18mcd5 this is chromium molybdenum steel. Vitus changed the
name of this material to Vitus XO in the 90's I'm not sure of the date.
SV980 has a main frame wall thickness of .9/.6 mm the chain stays and
seat stays were .8 mm and the fork blades were 1.0 mm if 28 x19 or 1.2 mm if
29x16 mm.
Vitus produced a heavier form of this tubing and called it Vitus 181.
Unfortunately, Vitus stopped making their steel tubing in the late 90's
if my memory is correct.
I built many a frame with Vitus tubing. I hope I helped.
Anthony Mezzatesta
Mezzatesta Cycles
Cranberry Twp Pa 16066
724-778-8224