Have you considered this option http://www.bike-eye.com/

Attached at the top of the down tube, it needs adjusted to the right position for you which takes seconds, and then just a quick glance at it when your leg is stationary - job done! You are still advised to actually look behind for a "lifesaver", though.

No connection - just a happy client.

As an aside, I tried one of these http://www.reevu.com/view_rv_dlx.asp http://www.guardian.co.uk/environmen...vision-mirrors years ago but my eyes don't focus that close. I'd need a set of bifocal spectacles made upside down just for cycling to get decent use from it. Looking on their website, they seem to be concentrating on motorbike helmets these days.