The following is a quote from The Fabricator’s Handbook by Ron and sue Fournier
The Berkley Publishing group New york, New york
Gussets – triangular pieces of metal welded in the corner of a joint – are one way to reinforce roll bars or cages. The addition of gussets gives extra strength and stiffness to a welded joint. USAC and NASCAR rules books specify 0.090 in steel gussets at all of the welds on roll bars. Each book details where the gussets should be placed. There are two advantages to gussets, one is generally know, the other is sometimes overlooked.
First, Gussets are an insurance policy. Gussets provide back-up strength to a welded joint – particularly one of questionable strength. I believe this is why the rule makers require so many gussets. It is a good idea.
Second, Steel Gussets Stiffen the entire roll cage structure by strengthening each joint. This strength helps the car resist twist, increasing the car’s torsional rigidity. This make a safer and potentially better handling car.
Because Gussets work so well for both safety and torsional rigidity, use them wherever you can. Even though a rule book specifies where they must go add extra gussets to strengthen any joint you think needs it. And don’t forget: a roll bar or cage must protect the driver. Make the cage as bulletproof as you can.
Here at vent racing we understand the value of gussets, cross members, diagonal supports and triangulation, that's what makes our cages safer, is our careful understanding of cage building.