On my flat bar bikes I use bar-ends and mount a Mirrycycle in the left one. By putting it in front of my hands I find that it is easier to adjust to give me the view I want, and easier to see than if they are mounted in the handlebar itself. Also I can put a stick-on spot reflector on the non-mirror surface, putting my front reflector further left. So far that has worked well. In the winter I also use the Cycle-aware helmet mirror because my neck mobility is further reduced by layers. I do use a Bell commuter helmet most of the time, and I'm not too impressed with their mirror system compared to other helmet mirrors, but it is functional although hard to adjust. Almost all helmet mirrors have pivots and breakaway features in event of a crash, but I try to wear safety googles when riding. (I use $10 AO Safety x-factors from Home Depot, they come with clear, yellow or blue lenses to cover all conditions for $30.) I haven't decided what to do on my new drop bar bike, but will probably just use a helmet mirror. I personally feel that some type of rear view mirror is as essential as bike lighting and ought to be required. If I can see a car in my mirror, I don't have to look back then and risk a swerve or hitting an unnoticed road hazard, I can wait until the mirror is clear to do my shoulder check. You still have to look back before you do a lane change or turn, but only having to check once or twice reduces fatique and "traffic stress" for me. Sorry to be so wordy.
