Bonneville America Forums Forums Technical Forums General Tech Mounting fiberglass bags?

Sounds like you are referring to what I call bag bounce. The bags are mounted to the frames that can only bolt in up top. The bottoms have nothing to stiffen them and prevent the bouncing or flexing from the bracket.
I have had my tusk aye bags on for about 4/5 years with no issue and they do bounce.
There is a brace available that will connect the bottom of the bags together and has clearance for the tire but it really hasn't been an issue for me.