Thanks for all of your comments. I am setting up two bikes with exactly the same configuration. The drive train for both bikes is clean, new, and well lubricated. One is geared, has derailleurs, but will always be in the 53/19 gear. The other bike will be single speed 53/19, no jockey wheels or derailleur. I will ride the bikes alternatingly over the 7.4 mile course for a month or so. This addresses the question of how much of a difference in mechanical efficiency there is between the two.

I understand that this still does not address the question of human efficiency on the two set ups, but at least it looks at one factor.