Last month, I finished building up my Eddy Merckx Professional. After some research, I decided to use Continental Grand Prix 4000S tires on that bike. Because the Merckx is “new,” I’ve been riding it on sunny days. When the roads are wet, I’ve been riding my De Rosa Professional. There was a significant difference in the feel of the bikes. Except for the Merckx being 1 cm larger in the seat tube and the corresponding geometry changes, the bikes are similar, both probably made by De Rosa with the same brake bridge and bottom bracket shell.
I attributed the difference to the tires. I can’t complain about punctures with the Specialized Roubaix Armadillo Elite – I don’t think I got one in 5800 miles. As is evident in the photograph, it did wear into a large, squared off, contact patch, 9/16″ (14mm) wide. I switched the rear tire on the De Rosa to a Continental Grand Prix 4000S and the De Rosa no longer feels like a truck.