FWIW, I have a simple Bell convex handlebar mirror as a backup (i.e. better than nothing) for those times when I can't effectively use my main M2Racer glasses-mounted mirror. In blowing mist or rain sometimes you can't look up to use a glasses-mounted mirror because your lenses will get plastered with raindrops. I would never want to rely primarily on the handlebar mirror, though. YMMV Fortunately my eyes don't have any problem using the glasses-mounted mirror. It is also useful as a pedestrian and to check out people behind you in the store.