Originally Posted by
PeteHski
I wasn't really thinking of the extreme ends of the drivetrain spectrum or even differing efficiencies across the cassette and chainrings in the same drivetrain. I was thinking more about the effect of changing the size of the chainring and cassette gear for a given gear ratio in the same drivetrain - related back to the OP's question. i.e. would a 52/19 be significantly more efficient than a 43/16 on the same chain-line?
As in all things, it depends on what you mean by "significantly."
I just looked it up, I gave some data and analysis in
this thread several years ago. You may have to scroll down a bit. In that thread there are also links to some articles on drive train efficiency that appeared in the IHPVA journal.