Years ago (20+), I vaguely remember thinking that it wasn't a good idea to put stickers on helmets because it could damage the hard shell. Years ago I had a polycarbonate helmet (if I remember rightly), nowadays I have a decent Arai helmet. Question; is it okay to put stickers on helmets? I was thinking of putting some reflective red tape on the back. God knows where I got this thought from about stickers damaging helmets.