Originally Posted by
longbeachgary
Part of the problem is that not all steel Merckx's are the same geometries/measurements. Merckx also made custom bikes for folks (even common folks) so that throws things off.
Merckx's own Molteni DeRosas measured 58.5 (center-to-center) at the seat tube and fairly short (even for the mid-70s) 57 at the top tube. Hey, that's my size! About a year ago a frame that his shop had made for his son Axel was up on eBay. It measured something like 63 seat tube x 56.5 top tube. I don't think Axel buys his suits off the rack.
Nowadays, most bikes of that nominal size have longer top tubes.