There was some conversation in other topic about blade type rollbar.
So, i have one like this. 32x3mm cro-mo tube and 260mm blades. Blades are 35 to 25mm wide and 6mm thick, steel of course.
Bar itself is more just a link between blades. This type rollbar works mainly with blades, i.e tube is stiff and blades are flexing (if they do) It depends how they are adjusted.
If blade is vertical, it´s very stiff, horizontally they are pretty flexible. Any position between those, are something between, ofc. To adjust, just loose bolt (most left head of blade) and tur to desired position. Or attach cable and make remote control.