Weight and aero more important than stiffness for riding consistently for an hour?
I'd have still thought stiffness was better than lightness but I'm no engineer
Neither were the people who made these bikes. Cycling has always suffered from chasing after what you could measure, and since back in the day they couldn't measure aeros (or at least didn't think it was worth trying) they chased weight which they could measure.
Weight and aero more important than stiffness for riding consistently for an hour?
I'd have still thought stiffness was better than lightness but I'm no engineer