[MENTION=210511]Slaninar[/MENTION] : No one had argued that roller wear had anything to do with (static) pitch. It was obvious from the start that pitch will not change if you remove rollers and remount a pin-only chain...

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I'd like to, perhaps, clarify a couple of things.

(1) it may well be the case that chain stretch is a good proxy for overall chain wear, such that measuring stretch is a good enough global wear metric.

(2) This is NOT synonymous with saying that the only cause of wear is the chain flexing around sprockets, which wears the pin-plate interface, provokes elongation, which translates into creep, which destroys everything. This model is overly simplistic. Chain drives are deceptively complex systems.

(3) The upshot is rather unimportant. Some people claim that all lubricants are more of less the same in terms of their impact on chain life, which flies in the face of the evidence gathered in the thesis that prompted this thread. But ignorance is bliss and in this particular instance, the consequences of misunderstanding the underlying factors are minimal. There are, however, a couple of outcomes that would be worth pursuing the current argument. First and foremost, there could be a better understanding of drivetrain wear, for the sake of knowledge itself. Second, there "might" be technological improvements resulting from such a better model. You may be aware that Ceramic Speed is launching a new lubricant which is said to reduce drivetrain wear in (essentially) half. Their testing appears to have been rigorous. Their conclusion is NOT based on chain stretch measurements, but on the diameter of pulley wheels. Their lubricant is said to contain additives that are likely to reduce the coefficient of friction between the chain and the pulleys (rather than focusing on the plates-pins). Ceramic speed focuses on speed (they aren't called Ceramic wear for a reason). Yet their innovations appear to have a meaningful impact on wear as well. At 75$ for an estimated 1 500 kms (10 applications @ 150kms each), only the most fanatic racer or KOM obsessed rider will consider this lubricant. But maybe something else will come out of a lab that will make sense and have a positive impact on commuters/long-distance tourers.