Originally Posted by
Andrew R Stewart
... real life shows virtually no difference in chain plate/roller wear on the top or bottom side of chains after many miles.
Far more important is the uneven wear of chainrings WRT the rotational alignment. It's very common to see more tooth wear on the rings when the cranks are at their power points then their top/bottom dead centers.
To the first part - since the rollers and pins are round, and spin around, they wear out the same way (symmetrically) no matter which way you make the circle with the chain when joining it.
As to the second part, I wonder if the chain gets evenly used all along its length. What I am getting at - is it always the same chain links that get engaged on the same chainring teeth when the cranks are at their power points? Actually thinking as I write this, it might be so only if you rode just one gear, like on a fixie, velodrome bike, but not on bikes with sprocket gears. Riding different gears probably scatters the use of the chain so it is used up evenly on all chain links. That would then affect measuring the chain for stretching. You would need to check a number of measurements to find one that is the longest. Of course, this is really an academic discussion.
