Quote Originally Posted by OakLeaf View Post
In a mirror, you're focusing on the thing reflected, not the mirror surface. If something's so close to your rear-view mirror that you can't focus on it, you've got worse problems than presbyopia.

Seriously, try it in your bathroom mirror. Wear whatever correction allows you to focus 10 feet or so away. Get close enough to your bathroom mirror that you can't focus on your own face. Now look at the wall behind you. Perfectly clear.

Same thing with a bicycle mirror. Same thing with your windshield-mounted car mirror, for that matter.
Interesting, and it makes sense when you think about it. I may try a helmet mirror someday. This is an interesting discussion, and I did find a lot in the archives. I really wanted this for the Tour de Cure tomorrow, and it sounded like there is a learning curve for a helmet mirror - no time for that, this time