I use Johnson & Johnson Hurt free tape as a wrap before the Bib goes on. I tried going without a wrap and I just got skin pinches galore so I canned that idea. So actually the only reason I us the J&J is keep my skin contained.
Thunder is right if you use a wrap you will eliminate the slippage. If your wrap and adjustments are right you should have no slippage AND your glan should be soft to the touch when your loaded. If your glan is tight then slippage is the problem.
11-2004 BPEL:8.25x6.25 . . 9+ by Spring is the goal AIR CLAMP