Originally Posted by
genejockey
Perhaps referring to possible problems running things like 8 speed rings with 10 speed. When I updated my Ritchey from 8 speeds to 10 by swapping the 7400 series RD and STIs for 7800 and adding a 10 speed chain, I initially kept the 8 speed chainrings, and it MOSTLY worked fine. But twice, my chain fell into No Man's Land between the rings. It didn't jam there, it just sat uselessly in the gap as I spun the cranks. I got the 9 speed small ring, which reduces the space between the rings and no problem. I suspect, but I'm not certain, that a difference of one speed between the generation of the rings and the drivetrain (and thus the chain) isn't a problem, but the greater the difference the more likely it is to occasionally fail.
Yes, from what I can gather, these issues arise because (a) chain width decreases as the number of "speeds" increase, such that (b) chain ring width must also decrease correspondingly. To maintain good front shifting, the spacing between the chain rings is also decreased, except for the respective specifications between 10-speed and 11-speed road drivetrains. Thus, 10-speed rings can be used on an otherwise 11-speed drivetrain without issues.