38mm or 40mm in 16 gauge is fine for most situations 50mm is a bit OTT, but can be used.So my best bet would be to go to 2 inch. Correct? And thank you for your input
Round tube has a higher resistance to both flex and torsional twisting than square for any given weight. Rectangular has less resistance to twist but greater resistance to flex than round or square.I believe @FrankCrank uses 2 x 1 stainless on his creations.
The problem with a trike and a vertically oriented spine might be twist/flex over rough terrain perhaps?
Square tubes have less of a tendency to twist I think. If we look at the commercial trike world what do they use?
Predominantly ROUND or SQUARE how many Vertical Oblong trike manufacturers are there out there? Why would that be?