Obviously it all depends on design.
What is your design? This frame is Mark Walkers design from 1990s.
This frame and swinging are suspension, uses 2mm wall light 7020 alloy tube and does a safe and very rigid 180mph.
The frame was built by my freind Mark. (From Martek Engineering, Grimsby, 1 mile from my house). That 1150EFE motor shown there in his workshop could well be mine incidentally...
Another build pic. Its not about the type of tube, but the frame
design. Thats where the strength comes from.