Tele would you mind answering a question for me? How much do you weigh?
I wonder if the higher speeds during cycling, drives air into the lungs at higher pressure, making breathing easier on the bike.
When I was a kid, I used to put my head out of the window of a Intercity 125 train(before the bridges

).If I faced the direction of travel, I just couldn't get My breath, and it wasn't as if there was a shortage of air.The air pressure was just to high.
During cycling it may well be that the breathing muscles are not worked as hard as when running, because of the above.Not completely sure though!