Originally Posted by
Trakhak
Not sure, but I think Grant Petersen might have been the one to invent the (spurious) idea that wider bars "open the chest for better breathing." I started racing in 1965, and I never came across that idea until I read it in a Rivendell Reader. It seemed an odd idea to me, since, for one example, the aero bars that pro riders use to ride time trials have the riders' elbows nearly touching. For another, racers climbing the Alps often ride with their hands positioned on the bars on either side of the stem.
For what it's worth, I've owned bikes with bars that were 42 cm, 40 cm, and 38 cm wide. I can feel the differences, but I don't have any real preference.
Grant Peterson was nobody when bars went to shoulder width.
However, comparing aero bars and vertical section of road bars doesn't really work. When you have your hands on the tops your elbows are pointed out, opening up the chest, and aero bars raise the elbows above the rib cage, but drops squeeze your triceps into the sides of the ribcage.