[Geo31]

Don't under estimate the strength of a X in a flat plane. Mass for mass, the X is stronger than bent tubes. Bent tubes are already longer than the shortest distance between two points and may bend much sooner than a flat plane X. IOW the failure mode of bent tubes is to bend inward. In order for the flat plane X to fail either 1) the tubes are literally ripped from the cage and if the force is that strong the driver is dead anyway, or 2) the force must be strong enough to stretch the tubes along their length (where they are strongest) before bending. Again, that much force and the driver is going to be dead anyway.

True NASCAR bars get their strength from mass. Just look at how much material is in a set of true NASCAR bars. Also, true NASCAR bars attach the verticle elements to the chassis for added strength. Oh, and NASCAR bars are NOT an arch and even so, most impacts would not be square againts the door anyway.

In the end, any monkey can build a strong cage by adding mass. A truly beautiful cage is one that provides maximum strength and chassis stiffness with minimal mass.