Hi all, a couple of weeks ago I presented some experimental results of comparing the relative friction of 4 different motion transfer methods - 16 teeth gears, 40 teeth gears, a perpendicular axle, and a chain. I have now published the build instructions for anyone wanted to run their own experiments. Please post any results if you do.
https://rebrickable.com/mocs/MOC-50089/TechnicBrickPower/relative-friction-measurement