Hi Dale and CR,
Most of my knowledge about earlier Colnagos comes from older Colnago literature, but some comes from having 25-30 Colnagos in my collection :-). So assuming the literature is correct, here is little info about Mexico vs. Super.
Mexico framesets first appeared in '75/'76. They were constructed of Columbus Record & SL tubing. My early catalog refers to "4/10 Record". This refers to the 10 tubes used to make a frameset, not including the steerer. I assume it means that four tubes are Record, and the rest are SL. The problem is that the catalog doesn't refer to which tubes are the Record tubes. Columbus catalogs spec the Record tube set to have all different tubes from the SL set, except for the fork blades, those are the same 0.9 mm. So this means that there can potentially be eight Record tubes in a frame. Did Colnago use four Record tubes to make up the main triangle/head, or was Record used for all the stays? I don't know. I do know that many people complain about the whippiness of Mexico frames in larger sizes. But that is the sacrifice one must expect from using ultra light tubing. Columbus intended Record tubing to used in record attempts on the track, not in a road bike. By the way, here are the weights of a complete Record tubeset (1650 gr.) and complete SL tubeset (2065 gr.) On a personal note, one of reasons I love to collect Colnagos is because Ernesto put out so many different professional models, primarily in the '80s.
Mexicos and Supers of this vintage are virtually impossible to tell apart. They both received the same lugwork and details. The only cosmetic distinguishing feature was the chainstay decal. Mexicos got the "Colnago Mexico" decal, while the Super got the "Colnago Super" decal.
In the early '80s, the Mexico incorporated a drawn top tube and down tube. This Mexico is refereed to as the Nuovo Mexico. Not everyone attaches the "Nuovo" to this Mexico. Even Colnago literature is inconsistent with using "Nuovo" every time. That is why there is a lot of confusion when attempting to read/talk about Mexicos in general.
According to Colnago literature, some of the models that came with the blend of Record & SL tubing are: Mexico, Nuovo Mexico, Profile CX, Profile, Arabesque.
> In a message dated 10/16/00 7:36:39 AM Eastern Daylight Time,
> firstname.lastname@example.org writes:
> << I meant to say that there were some called the "Mexico" that were of
> questionable quality. I guess some of the "Supers" were also poorly made. I
> wonder why they varied so much? >>
> I think that in the late 1970s and early 1980s, Ernesto Colnago's genius for
> marketing and sales pushed him to farm out a lot of production and some was
> I think that the Super was the model most likely to be loose in quality.
> Those came in the USA in droves to the mail order houses and to any start-up
> importer with money. This is the same time frame in which serial numbers
> were not even used ... De la Rosa and Kolin referred to this "farming out"
> situation by Colnago in the preface of The Custom Bicycle Book, using that as
> a reason to eliminate him from the book.
> Genuine "Mexico" models, alleged to be made of super light Columbus "Record"
> (straight gauge!) and "KL" (butted), were most likely built in Ernesto's
> workshop. These "real" Mexico bikes were usually very good. Also confusing
> this issue was Colnago's tendency to slap decals on any Colnago with
> references to the Mexico Hour Record. It is sometimes tough to know which
> model Colnago you actually have.
> I would bet Marc Boral knows a lot about this. What do you say, Marc......?
> Dale Brown