Originally Posted by
chas58
very true above 20mph - aero is the majority of the total resistance. You probably know it goes up exponentially, where friction is linear. At 10mph, aero is trivial and friction is the vast majority of the load.
In my case, I'm in roughly the same aero position on the mountain bike or on my hoods with the gravel bike. Aero wasn't a factor in my test.
MTB's have wide flat bars and you are more upright because of the geometry but ok... 2 hours on an MTB will never feel the same as 2 hours on a road bike. The MTB will always beat you up more and it's not mainly the weight. Wide flat bars are not conducive to comfort on a long ride.