Originally Posted by
dscheidt
You suggesting that the abused chain I just threw out was some relic from the bushing era? it wasn't. It was a perfectly modern KMC chain. The increase in bearing area for 9 to 8 speed chain is substantial. Increased bearing area means lower loads, which means longer life.
I guess I'm not sure. Do 8 speed chains have larger diameter pins or are the links just wider (use longer pins of the same diameter)? Most of the wear occurs where the inner link rotates on the pin. Longer pins and wider rollers aren't going to do much to help the chain last longer. In fact I could see where longer pins might actually make for weaker chains.
Take a look at how chains are put together:
I'm not endorsing this chain. It just came up early in the search.
And in case you're interested, someone did some
endurance comparisons between 9 and 10 speed chains. The 10 speed chains laster longer.
Single speed chains last a long time because they're not getting torqued by derailleurs, are always running straight, and are not being spun around jockey wheels. It's not because they're inherently stronger.