Originally Posted by
Hypno Toad
However, the speed of the bike is the true OUTPUT of the bike.
Indeed, but without a controlled input you cannot determine what causes the differences you're seeing.
Originally Posted by
Hypno Toad
And for a simple analysis of my bikes, looking at average speed over a specific section of road has merit.
It does. You have now identified that you are usually faster over one section on one bike than on another one. You cannot, however, determine
why you are faster on one bike over the other. It could be that the fit allows you to generate more power, or maybe it puts you into a more aerodynamic position. Maybe it has better drivetrain efficiency, or it is lighter. Or maybe you get a tailwind more often on one than on the other, or you have a bigger breakfast when you ride one of them. Maybe even a bit of everything.