Old SRAM PC-870 chain (top); new SRAM PC-870 chain (bottom).
The chain on my De Rosa started skipping on the lower gears on the Campagnolo 8 speed cassette. Unfortunately, by the time the chain was skipping, the lower cogs on the cassette were worn out.
Measuring from the center of one rivet to the rivet 23 away on a new chain is 12 inches (~30.48 cm). My chain was over 1/4 inch longer. Park Tool recommends replacing the chain when it is 1/16 inch too long.
Replacing the 8 speed cassette is a problem because of the dearth of parts, considering I need a ≥28 tooth lowest cog. I’ve found Miche 13-28 Campagnolo compatible cassettes on eBay in the UK and Italy, but then I start to wonder whether I should keep trying to support shifting components that were last produced in 1997.
I’ve also found on Branford Bike that a Campagnolo 9 speed hub could be used by dropping one sprocket and using a Wheels Manufacturing 8 speed spacer kit, but that spacer kit is also no longer available.
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.