I have them because I layed over softly on a climbing secition of a trail that had a digout between to big ass trees. When it layed over I was pummled with a root that nearly broke my femur. Had I had the tube on there it would have prevented that section from possibly doing what it did. So I decided to build it. Will that tube door save me from being hurt? Probably not! Does it make me feel better then having nothing at all? Hell yes! For me its more of a comfort factor. I dont wheel any harder cause I have it just adds a little security and piece of mind. (Plus it makes the wife feel safe when she rides in it)