Originally Posted by
Racing Dan
Yeah, at lower speeds tube and tyres are your best bet if you cant have both. Aero gains are always measured at ludicrous speeds, because power to overcome "wind resistance" goes up by the cube of the speed. For instance power to overcome wind resistance at 50 km/h is almost double that of 40 km/h and 4.6 times that of 30 km/h.
I assume that it's actually relative wind speed that's important. It's not at all unusual to find days with eg. 15km/h tailwinds for portions of a ride's course.