Originally Posted by
DaveSSS
My experiment was using Campy 10 chain on a new cassette for 6000 miles. It showed less than 0.25% elongation, properly measured over the full chain length. The roller wear was huge and so was the side clearance wear. It caused new-chain skip when a new chain was installed. The wear pockets created by the worn rollers caused this, not chain elongation. You may also find that the sprockets that skip with a new chain will not skip using a chain with only a few hundred miles of break-in wear. That can allow a cassette to be used another 3000 miles instead of being tossed.
I still think it has nothing to do with the diameter of the rollers (i.e. roller wear). It has to do with the chain pitch.
If you measure a brand new chain, you might notice it having under 0.5" pitch, on average, because the factory grease won't let the inner plates get all the way to the pins - which gets sorted out after a very short ride.