I was thinking one day, it kinda hurt but.....my fenders were making a irritating tinkle, rattle, ping pop ect...so to the auto store I went and purchased some spray can of undercoating, and presto after a little masking and a day of drying a super quiet ride again.....don't use the kind that goes on real thick the cheap stuff works great and adds very little fat to the bike. It also makes the real sticky mud wash off easier. Oh yea it will only stick to metal fenders.