I've often heard people say that it's the engine, not the bike. Last night was a good example.
I took my gravel bike to the A group ride, because my aero bike is setup for a TT on Thursday and I didn't want to mess with it. So I put on my road wheelset with 28mm GP5Ks (measure at 30mm) and ended up setting nine segment PRs, riding my non-aero, 4lbs heavier, endurance geometry gravel bike.
I think part of it is the whole "comfort = speed" thing. Some of the roads we were on are pretty crappy, on a road bike you have to be careful and you get a lil beat up in some sections. On the gravel bike with bigger tires and compliance built-in to the seatpost and bars, I was very comfortable and had no problem pushing through the rough sections.
Yes, in a lab, aero trumps all, but in the real world, sometimes it's a lil different. That being said, I'm still riding my aero bike with 88mm wheels and clip-on aero bars for the TT.
