Do hardened chains cause more chainring and cassette wear? I was reading the Sept 2016 issue of Bicycling where they were reviewing the SRAM NX series. The blurb for the SRAM chain (below) states that "The PC-1110 chain SRAM recommends for NX ... has performed its duties as well as SRAM's higher -end stuff. And because it hasn't had premium hardening treatments, it actually  may be gentler on your cassette and ring than a more expensive chain."



Any truth to this or is this just advertising-speak that snuck its way into the review? This is Bicycling magazine, after all.

Do hardened chains cause more wear?
There are two sides to this question, for the two places chains contact chainrings and cogs with force: the outer plates and the rollers.

There is probably a grain of truth to the statement in question regarding the hardness of outer plates. Sometimes you do see chainring ramping get worn to the point of not performing as well as a result of the rider, usually a racer, habitually shifting under load. Every once in a while you see it somewhat in advance of the teeth being worn. I don't see why this effect wouldn't be exacerbated the harder the outer links are. (That being said, I'm not sure which if any chains, expensive or not, have outer links that are any harder than other ones, since you don't really gain anything by it, and I'll bet the writer has no data on this either.)

For all the other parts of a chain - pin, roller, and inner link (or the bushing in the case of a traditional 5-piece chain) - you want it as hard as you can get it as long as the other mechanical properties (ductility being the big design counterbalance to hardness here I think) are what they need to be. That's how you get a chain that resists elongation the best and in turn keeps cogs and rings going longer, which is what most cyclists are interested in.

So basically the statement is misleading.