I had been looking for an SR group for another project and thought this complete bike was at a good price to strip, use what I needed and sell the rest. The fact that it was a Mexico was a real bonus.
When I went to take a look, it was pretty obvious that this was not a Mexico or Super, and I had my doubts that it was even a Colnago. There are a lot of fakes out there. Here's a picture of this 52.5 cm frame and fork:
Here's what I was bothered by:
- The top tube had three cable guides. All of the Supers and Mexicos I've seen have had only two.
- The lower head tube lug had no club cutout.
- The right chainstay had an internal cable guide.
- The seat stays had a double taper, but the seat stay caps were not fluted or stamped with Colnago. Chainstays had no Colnago stamping either.
- The bottom bracket shell had the Colnago club cutout, but it didn't look quite right to me. The base of the club was sort of rounded, not flat. The club cutouts on the fork crown were the same.
- Is this a real Colnago?
- If so, what model is it?
- How old is the frameset?
I mentioned above all of the things that made me wonder if this frame is genuine. I will go through them one by one. The three cable guides are not typical, but it turns out that they were used occasionally. Here's an advert for an 84 Master showing 3.
Club cutouts on lugs, fork crown and bottom bracket: Like I said above, no cutout on the lower head tube lug. Here are some pictures of the fork crown and bottom bracket.
And here are some pics of known Colnagos:
76/77 Super 
Seat stays: Not much to say here. They are tapered on both ends like other Colnagos I've seen but the caps at the seat cluster are flat with no engraving. I have not been able to find photos of other Colnago frames with similar stays. The seat post diameter is 27.0 mm, which is consistent with mid-70s Columbus SL tubing.
Seat stays: Not much to say here. They are tapered on both ends like other Colnagos I've seen but the caps at the seat cluster are flat with no engraving. I have not been able to find photos of other Colnago frames with similar stays. The seat post diameter is 27.0 mm, which is consistent with mid-70s Columbus SL tubing.
Chain stay internal cable routing: Check this out, definitely unusual:
Functional, but different. I have not been able to find any similar arrangements on any frame, Colnago or not.
So is this a real Colnago? Yes, the general consensus is that it is genuine, but that it is not one of the higher end models. Instead, it was a quality frame made for the export market in Germany or the Netherlands (or elsewhere). There was a Colnago model called Sport that fell into this category. There are also plenty of stories about Colnago attempting to take advantage of the 70's bike boom by producing Colnago-badged frames for the mid-level market. Production of these was farmed out to a number of builders. This frame may have been one of these. One thing I discovered when disassembling the bike was that the SR head set had too high of a stack height for this bike. Looking down through the top, there was at least 5 mm of space between the top of the steerer tube and the lock nut, despite having no lock washer or spacer. I imagine that the lock nut was only engaged by a few threads (rather dangerous). SR headsets have a stack height of 42mm. I would say that this bike originally had (or was intended to have) a lower level Campy Gran Sport headset. These have a stack height of 34 mm. This is another indicator that this was a bike boom special meant for a lower price point.
How old is the frameset:
The person I bought this from did describe it as a mid-80s bike though, so what about that? I don't think so! My guess is mid 70's. The fork is most telling with the clubs on the crown and the tangs with two holes. This puts it as 1973 or 1974. Both frame and fork are stamped with the number 19 which indicates that they are matched. Another indicator was that the fork crown and brake bridge were intended for the non-recessed nuts. Colnago switched over to recessed nuts in 1977-78. On this particular frame, some previous owner had drilled out the crown and brake bridge to fit the SR brakes (which were actually mid 80s).
Also a good indicator is the long Campagnolo 1010-A dropouts on this frame. Colnago started to use the shorter 1010-Bs around 1976. The stamped number 19 may be a serial number but it may also be a sizing reference.
Wrapping things up:
I think, based on all the info I've gathered that this is a production frame produced by Colnago in the mid-1970s to sell at a discounted price to take advantage of demand. The components were not original to the bike (because of the brakes, varying ages of components, and the misfit on the headset). The frame was repainted to 80s colors (and decals) and some modifications may have been done at that time (top tube cable guides, chain stay cable routing - though because of the chrome, this was probably original).
A few measurements (as good as I could get them):
Issues:
A few measurements (as good as I could get them):
- Seat tube (center to center): 52.5 cm
- Top tube (center to center): 54 cm
- Chain stay (from center of bottom bracket to center of drop out: 42 cm.
- Frame weight: 1.86 kg (2.22 kg with fork)
Issues:
The frame is in good shape generally. The paint is a re-spray and not bad, though not the greatest. There are a few rust spots, the worst being on the underside of the top tube to head tube lug. I scraped it a bit and it doesn't look like anything more than a bit of surface rust:
There is a small ding on the underside of the downtube:
Here's a picture of the rear brake bridge showing how it was drilled out. I believe that there would have been a small washer brazed on the back side.
None of these issues affect the use of the frame as is and should be easily corrected if restored.
Finding a suitable headset may be a challenge because of the low stack height necessary. The Tange Levin CDS is a good low stack headset that may fit.
