Seriously though, it seems those tubes would be predisposed to bending inward, pinching the tire upon impact. Why have they done it like that? I'd figure they'd want them to bend outward away from your breaks, tire and spokes.
tubes a butted,that means the tubing wall thickness is greater near the ends plus the flare in the middle makes them strong yet able to flex a bit...and a frame is the sum of its parts,it's everything working together...