Merckx/Kessels fans:
I have posted some pictures associated with the topic of Merckx + Kessels on WoolJersey at the link below:
http://www.wooljersey.com/
Photo 00 is a kessels display that was pictured in a circa-1976 Big Wheel catalog.
Photo 01 is the photo from Chris Protopapas of Merckx's 1973 bike at the Kessels booth at the 1974 NYC bike show. The bike has the stay cap design I've seen on other Kessels bikes, as well as some details I hadn't seen, like holes in the fork crown. It was also rigged with only two top-tube brake cable clamps, and I remembered seeing this in some racing photos so I went through a few magazines.
Photos 02-05 are from Mirroir du Tour 1971 and these happen to show Merckx on a bike that I suspicion might be a Kessels. (While you're looking, don't forget to check out the nice clean drillium on Zoetemelk's brakes! )
I'm thinking of the Merckx bike in photos 02-05 as possibly a Kessels based on the Kessels-like stay caps, and the tubing sticker on the down-tube above the shifters. It also just happens to have the same seat-post milling as Chris's photo, and the same hex-bolt on the seat-post binder, and the same 2 top-tube clamps.
Upon the topic of the paint: in early seventies Tour photos Merckx switches between bikes that have two paint schemes: one is the familiar one with the yellow and pink bands on the orange seat tube and the blue section with yellow letters on the down tube -- the other has a black section on the seat-tube and dark lettering on an all-orange down tube. Since Chris's photo showed the Kessels with the second rig, I briefly tried a hypothesis that the black-seat-tube bikes might all be Kessels. It is another curiosity.
In the past I would have identified the bike in the 1971 photos as a Colnago based on the holes in the fork crown.
One other interesting tidbit about Chris's photo: the saddle appears to be the quilted version of the Unica Nitor.
Of course race bikes are often painted as something else, and a while back there was a post recounting that Merckx told Brett Horton that he sometimes swapped the fork from one maker onto the bike of another maker. Amazingly, this does not dissuade me from theorizing about old photos, heh heh.
Brad Stockwell
Palo Alto CA USA