18°C, NW winds CR:38.5 miles

I daren’t ride the race bike on that chain, it looks like another pin is pulling out so I have binned it. The replacement is the same type- a SRAM 870. This time I did not risk joining any links and took off spares in stages before finally using the power-link to finally join the ends. The ride was okay, but unexpected gear changes still happen on the 17t cog.
I bet the derailleur hangar needs aligning- that’s a job for the shop though. the tool is too expensive for occasional use. I imagine that such a fault would allow good gear changes on some sprokets, and not on others. If I adjust the cables, then it merely change which cogs skip about. On this ride, the top & bottom ratios are okay, and the lower-middle ones play up.
Another contributory cause might be bearing wear on the freehub. The Campy service centre said they could fix that.

SRAM Power Link (Photo credit: Wikipedia)

12/13/14/15/16/17/19/21t
17 is the worst.