Couple things:
Where I ride, there is ALWAYS TRAFFIC. I don't need a mirror or Varia to tell me that. I did borrow a bike once that had a bar-end mirror, and found it useless. It just told me what I already knew: I am being passed by traffic. There's no way I could tell if some car was going to be a foot or two too far right. Maybe if I did nothing but stare at the mirror.
For road position, in my state and I think it is the uniform vehicle code, the shoulder is not part of the road, and FRAP does not mean ride on the shoulder. That being said, on most of my roads there is a good shoulder and that's where I ride. There is a road (Kam Highway on windward side) that the shoulder isn't all that wide, and in some places they have the rumble strips and it is very easy to accidentally get on them (which isn't fun). There's another road (Kaukonahua) that they repaved a couple years ago and had a narrow but decent shoulder but they ruined it with rumble strips. So I take the lane, but I only ride it in the downhill direction now and can make the 35 mph speed limit (still get passed though just the same). There the Varia could be useful as the road curves and cars have to cross double yellow to pass me.
scott s.
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