I’ve never liked helmet mounted mirrors. They seem to get knocked around and off while the helmet rides in my toolbox.
I like the one I clip onto the temple of my glasses. Some people never seem to get the hang of seeing behind with these small mirrors which sends them to the larger field of vision models which are usually helmet mounted. Handle bar mounts never meet my needs. I can’t just twist those handlebars for a better view–doing so likely takes me out into traffic.
Oh, and Neil, the temple mounted mirror goes on the left temple. Of course, Neil usually forgets to bring his mirror. For me it is a habit. I feel uncomfortable without it. I’ve never gone so far as to wear the mirror even when off the bike though I have caught myself trying to look in a non-existent mirror.–Corrie
The main reason I wear a helmet is because I really like having a rear-view mirror. I’ve used several mirrors over the years, and I definitely prefer the kind that mount in the vicinity of my left eye over models that mount on the handlebars.