Originally Posted by Trakhak

I wonder how the "narrow bars constrict breathing" belief arose. It's been around for decades (maybe back as far as when "ankling" was a hot topic among touring riders). Like many such ideas, it's superficially plausible. But: how can your arms, which can pivot freely and effortlessly up and down, left and right, possibly constrict your rib cage?

Real-world counter-examples:

Pro riders climbing in the Alps, Pyrenees, etc., can often be seen grasping their handlebars with one fist on each side of the stem, riding that way for minutes at a time. Time trialists ride with their elbows just a few centimeters apart. Graham Obree is an extreme example: he set one of his hour records with his arms folded under him, elbows together, upper body weight supported by them. An hour record.

When I lean my forearms on the top of a desk or table for a couple of minutes and move them closer together or farther apart, my respiration rate doesn't change. Check my work.