Did you just say "your small tube..um theory"?
If the formulae for the torsion constant of a thin walled tube, and the bending stiffness of a thin walled tube, were my invention, or a pure flight of fancy, I would be a successful engineer indeed. Instead, I'm merely a scientifically literate person, unlike you, "jamesdak".
Math: even small changes in diameter make big differences, since everything multiplies on the cube of the radius. And tires make bigger differences than tubes even. But don't let any of that get in your way.
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Good night...and good luck