Originally Posted by
rachel120
Not being sarcastic, this is an honest question for those who feel a mirror is not needed. How do you watch the road for rocks and broken glass and other hazards, keep your eye on the car waiting to make a left and the car in the side street to make sure you can react if they don't see you or mistime and you need to avoid a collision -and- keep an eye on the traffic behind you long enough for a car count, a speed estimate of each car, lane positioning and lane changes and making sure the guy coming up fast directly behind actually slows down in time without a mirror? With peripheral vision and a mirror I can do both safely. I don't see how I could watch so diligently to the rear and watch the road ahead without one.
I only have a mirror on one of my bikes, but it's the one that i use for group road rides, so it spends the most time in traffic. I view the mirror as an extension of my peripheral vision to the rear; I can get a rough idea of where my riders are, and if we've got a car back. As far as car count, it's either one, or more than one.
At bicycle speeds, it's no big deal to scan far enough up the road to avoid any major hazards long enough to do an over-the-shoulder check. Something you learn on motos, where you're going down the same road, just 2-4x faster. In fact, mirrors on most motos aren't a whole lot better than the ones on (velo) bikes. Add in a full-face, visored helmet, and shoulder checks become necessity.
I never make a move based solely on my mirrors.
Also, the act of turning your head to check behind/ beside you also serves a visual signal to other traffic around you (if they're paying attention) that you may be about to do something other than keep riding along.