I need info on engineering with sq tubes. I designed a SWB bent with 2"x .065" sq and 3/4" x 1-1/2" rectangular for the rear forx.....this tubing is very strong and may be strong enough for 500lbs....this would be good, I realy want to know what I'm getting my self into before I do it.

it's just a straight shot back to the forx from the crank. 20 and 26" wheels.

I brainstormed this formula, is it valid?:

psi devided by the wall thickness, times 2, times the depth, devided by the leigth between pivot ponts (or should this be the area of the arc between the pivot points) divided by maximun gravity???