In 1977 I started wearing a Bell Biker on my 15 mile urban commute because I thought drivers would take notice and give me a wider berth. Then I fastened a mirror to the helmet so I could see what was going on behind me. I couldn’t imagine driving my car without rear view mirrors, so why not the bike? Just became a habit from that point on. The helmet I was wearing a few years ago when I went over the bars and landed on my head is split down the middle from the point of contact at my forehead. It hangs near my bikes in the shed. I don’t think I’ve forgotten a helmet since.