Pour over Rust 15 (POR15) is not a "fix" if your frame has a case of rust thru,it is supposed to be in cases of non structurial rust areas,if your frame has surface rust but not rust thru ,that is ok to use on it,or if you remove the epoxy coating and apply POR15 over the bare frame that is fine too,but the best bet is to repair any rust and then apply POR15,also after applying POR,it is a good idea to paint over POR15,because it is sensitive to light. Claude 000570