Here is a bike mirror you can mount in a few seconds on your wrist watch band or a wrist sweat band (though sweat band requires extra stiff mounting surface of some kind else the mirror will jiggle).
To use it, just raise your hand to the level of your eyes ( a line from Phantom of the Opera - my favorite opera).
When you don't need it anymore, just slide it off sideways and the magnet under the watch band will come with it. Then just store it on one of the steel rails under the bicycle seat.
Great Idea: (thanks for this idea to Kudzu) If you don't like the idea of using magnets, use velcro to secure your mirror. I'm thinking of using this on my gloves for the winter as my wrist watch will be hiding under my coat sleeve.
Note 1: you can also wear it in your cubicle.
Note 2: you can't shake this thing off.
Note 3: magnets are good for you right? And it doesn't seem to effect my watch at all - unless you have a built in watch compass - definitely affects that.
Note 4: for you girls that need to check your makeup while your riding or you guys to see if anything is in your mustache - this mirror is the fix - can't do that with a helmet or glass mount mirror and it is real tricky to do while you are riding wth a handle bar mount mirror. And a convex mirror takes about 10 years off your age.
Note 5: I went out biking and forgot my watch - but no problem - I just picked my magnetic mirror off my bell, where I store it, used it when I needed it and then put it back - wrist band optional.
Caveat: I will be the first to admit this mirror mount is not the final solution - a definite downside of it is that the rider is inherently unstable when using it by having only one hand on the handlebars. It is just another option. Also, forgive my rants and unkind remarks about other mirror mounts - I am an opinionated, crotchety old 60 year old (59.5 actually) unlikely to change my ways.
- two strong neodymium magnets around 1.5 centimeters in diameter - or bigger if you don't trust their strength
- 2 pack blind spot round stick-on wide angle convex mirrors (do yourself a favor and put the second mirror of the 2 pack on your car)
- duct tape
Now I seem awfully set against eyeglass and helmet mounts - the benefit of these is that they are always there and you don't have to take a hand off the handlebar - but then I learned to do that when I learned hand signals - we do use hand signals right (who am I to preach - I don't even usually wear a helmet)?
This mirror also works on my unicycle - fancy that.
Update Aug 18: Just saw that there was already a KickStarter project out there for a wrist mount mirror. Nothing new under the sun I guess. Not magnetic though.
Update Sep 8: Saw this commercial wrist mirror product: http://www.likecool.com/Wristworn_Mirror_for_Cyclists--Bike--Gear.html