Good Lord, you mirror fanatics are as bad as the Go-Pro zealots. Full disclosure, I use a mirror, I know what it can and cannot do, and it cannot warn you about some cager sneaking up to take you out from behind unless you look! And if you are doing it right, you won't be looking! Your eyes will be on the road where they belong. Or not... maybe that's why most cyclists are injured by collisions with fixed objects than by being struck by other road users... ... Ford spent millions on a laser system that would alert a driver if a vehicle coming up from behind got closer than 8 feet. Hmmm. Given the size and location of all the mirrors in high performance automobiles why do you think such a system was necessary?! Hmmmm? It never went into production btw, like so many of the bright ideas that come out of the brainstorming of engineers. If you aren't sure... stay in your lane? What a concept.

But... ... lets say I don't know my @$$ from a Shetland Pony. Let's imagine that despite your attention being focused on the woman coming out of Starbuck's in a Vampirella costume, a mirror actually could override your temporary discombobulation and allow you to take efficient evasive action. Let's say that was actually possible. Do you think the best tool for that task would be a mirror 3/4" in diameter? I scoff in your general direction. Were I the o.p. looking for a new weapon in the war against terror, I would consider no less a piece of ordinance than the helmet mirror from Efficient Velo Tools. 2.75" of no nonsense rear view and it is the same distance from your eyeball as the dentists mirror is. Yeah baby! You might actually see something coming in that mirror that you weren't expecting, but I doubt that. Your ears will tell you more about what is or what isn't overtaking you than even the amazing "Safe Zone" mirror by EVT. A mirror is very useful for making attractive (to onlookers) lane changes and other maneuvers without having to twist like a pole dancer at the Jungle Room while doing it. Any other powers or attributes are (dangerous) artifacts of your febrile imagination. FWIW.

H