Originally Posted by Abe_Froman

Well for the purposes of discussion...I think we can exclude rider position from (at least this..) the discussion. That's something that is adjustable, and not tied to the particular bike. Cross bikes are roughly a centimeter higher, centimeter shorter at the front. I've had a professional fitting...any road bike I got would have the exact same setup as my cross bike right now in terms of rider position...wouldn't want to go any longer or lower. Not at the moment, anyway.

Also...gearing is not a factor either. I'm in Chicago...it's not like we have descents haha

So really...most things could be fairly standardized...wheels, tires, position, etc. The things specific to a cross bike that would slow the bike down IMO would be the width of the frame...big wide fork, round tubes, but round downtube, wider chain and seat stays...

I've seen some fairly large differences in independent testing of AERO frames...20 watts plus at around 30mph. That sort of leads me to believe an aero frame benefit relative to a totally UNaero cross bike could be upwards of double that. But of course I'm just wildly speculating.