When I bought the Campagnolo groupset, I did not install the chain. I was annoyed by the connector pin that requires a proprietary tool. So I installed a “Campagnolo compatible” KMC chain instead. When it broke, I replaced it with the same model of KMC chain, partly because I forgot I had a Campagnolo chain at home, partly out of laziness. The daft thing is that all this time (and distance of more than 10,000 km), I had been wondering about compatibility issues arising from mixing products from different makers.
I just found out the answer: Don’t mix.
It’s a rather embarrassing tale, but here it is. When I first installed the group set, with the KMC chain, I noticed that shifting from the third smallest sprocket to the second smallest sprocket tends to be lazy. Furthermore, shifting from the second smallest to the smallest was often very difficult. The latter takes the fun out of the moment where you want to bomb down a descent just after cresting the summit. Annoying, to say the least.
Shortly after the initial installation, I went to consult Michel, who is a Campagnolo certified mechanic working at the shop where I bought the group set. He checked to see if I had installed everything correctly. Indexing and everything else was just fine. He said that KMC make good chains, but mixing can cause problems sometimes.
At this point, most people would get the idea. Not me. Instead, I devised shifting tricks to make the chain get to the smallest sprockets. Too embarrassing to get into details…
I recently had to reassemble the bike after I got the frame back from a makeover, so I took the occasion to install the Campagnolo chain I had sitting on a shelf.
There are several mentions on the Interwebz about the difference in the width of the links amongst various makers of 11 speed chains. According to my digital caliper, my Campagnolo Chorus chain measures 5.48 mm whilst the KMC chain measures 5.53 mm. Does a delta of 5/100th of a millimetre make a difference in performance? I don’t know.
I also note that the way the outer links are bevelled around the edges is completely different between the two. Is that the reason? I can’t be certain, but it seems a bit more than plausible.
Smooth shifting all the way up and all the way down. No tricks required. There seems to be improvement also in the way it goes from the smaller chain ring to the larger chain ring.