Originally Posted by
steeltrap21
I think I have a better way to address this. I have a Stages power meter which measures watts at the crank and an old Compu-trainer (if I can find all the pieces) that imposes load at the wheel. I could calibrate the two with the single speed at 150 watts per the Stages, and then see how much (if any) additional power is required for the geared.
If this is something which you are really passionate about, why not do your own trials? The fact that there is little concrete data may be that it is intuitively determined that all things being equal, not having all of the "extras" a geared bike requires will result in more efficiency.
Frames can be made to be equal but once you introduce all of the components required for geared set-ups, you begin to add a lot of weight. The shifters, the cables, the derailers, the extra cogs, etc. Even if you were to use an IGH there is still a significant weight penalty.