It depends on the location, I used a variety of 3/4" and 1" OD tubing with either .049" or .035" wall thickness. I think one section was actually .028", but I'd have to look back through the design.I'm curious; what diameter and wall thickness was the chromoly you used to build your tube frame?
Very nice build.
A future build will be completely chromoly without aluminum side panels. The panels actually add a lot of unnecessary weight. It gets tricky though since the panels make a nice alignment datum.