Originally Posted by
FBinNY
I hate to correct folks but this is wrong. 7, 8 & 9s chainring separation is the same, but 10s is definitely less. When Campagnolo made 10s cranks rather than thin the spacer built into the right crank spider, they milled a recess into the outer chainring's mounting area moving it inboard a bit. Don't hold me to this but I believe it was by 0.8mm. This is the only difference between the Campy 10s and 9s cranks and chainrings.
Given the prevalence of 9/10 speed cranks at one point, not every manufacturer was/is adjusting spacing to accommodate 10 speed chains. I'm aware that some 10 speed cranks do have tighter spaced rings and I commented on that in my post (though I didn't give specifics as I'm not certain of the numbers).