hi wondering if any body has had a tank bib on there bike and what protection is underneath the bib. I am thinking of putting one on my super glide but worried it might scratch the paint work. any help please

Tank bibs are supposed to stop stonechips etc.
If you are worried that the tank bib might scratch the tank, I'd say you might have some sort of obsessive compulsive disorder and should seek expert help at once!.
Seriously though, I thought I saw tank bib liners at the local shop today that were designed to stop that problem. So you might not be crazy.