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.
After building a new wheel and acquiring a new 13-26 Campagnolo Record 8 Speed Ultra Drive cassette, I needed to change the cog in the final position from a 26 tooth to something larger so I could have a lower gear for hills. My normal ride has a Category 3 climb, according to the Tour of California’s rating of bike climbs. There is also a short 9.5% grade that I dread every time I get there, so the extra 2.6 gear-inches makes a difference.
I couldn’t find an 8 speed Campagnolo cog larger than a 26 tooth but there seemed to be Miche (Campagnolo 10 speed compatible) cogs with 27, 28 and 29 teeth for sale on eBay. According to every source I found, Campagnolo 10 speed cogs would not work on an 8 speed hub, mainly because the splines are deeper and there is a stepped-ridge on one of the splines. That’s where the Dremel cut-off wheels come in. After a few minutes with the cut-off wheel and some chamfering of the splines with a file, the 10 speed cog was now 8 speed compatible.