I used to do that back when helmets were heavy and had hard shells. I did usually try to do it in shady spots. I'm not sure I would do it with today's lighter helmets, unless I was going to buy a new one every year or two. They just don't take being knocked around as well, especially if other people are knocking there bikes into yours. My Bell V1 still looks better than the lightweight I replaced it with. I would probably still trust that old V1 despite its age, but not the old lightweight.