I think the mirror on my bike is its most important safety feature - more important than helmets. While helmets have been overwhelmingly accepted, I don't see the same level of acceptance for mirrors. I think there are two main reasons for this:

1. Road bikers disdain mirrors as dorky. They pride themselves in being able to turn their upper bodies around effortlessly to check for traffic. This attitude trickles down so that the less flexible riders who don't want to look dorky, disdain them as well.

2. Many mirrors don't work well. The first mirror system I tried on my drops bars simply didn't work and I assumed that mirrors in general didn't work so I gave up on them. I put a mirror on my flatbar and it works great. However, on another flatbar bike, the mirror doesn't work well and is actually annoying.

Mirrors make me a better rider. Before I had a mirror that worked, I would hesitate to take the lane because I was never confident that there wasn't a car behind me. With a mirror, I take the lane confidently and put myself in much safer positions going trough intersection. Before I had a mirror that worked, I would listen for cars coming up behing me as I rode on the rural roads. It was nerve wracking at times because sometimes (often) the shoulder of the road was broken up or had debris. With a mirror, I confidently veer around these obstacles and keep myself safer. Before I had a mirror, I would get ahead of the pack or my fellow rider and wonder "Am I too far ahead? Are they okay?" With the mirror, I can keep track of my fellow riders and not have to stop to see where they are.

I would like all of us to advocate for mirrors on bikes. Encourage riders you know who don't use mirrors to find one that works. We're all better off when we're all safer.