Originally Posted by
freemti
For touring (I commute on the same bike) I use it a lot to check for traffic that's going to pass me at speed when I'm on roads with small or poor shoulders. I just like to know when that semi is going to whizz by doing 50 mph, I'll make sure I have a good grip on my bars and that I don't chose that moment to drift over into the lane.
For that very same reason, I have a helmet-mounted mirror that I use during my commute. My commute takes me down one fast road with some big trucks. I've become used to watching all cars as they come up behind me, so that I know how much room they are giving me and how fast they are coming. So far, all have seen me and I've never had to bail into the shoulder. But if one comes in a big SUV talking on a cellphone while putting on her makeup (I've seen it), I can move over.
The other day, I started counting the number of people in afternoon traffic with a cellphone pressed against their ear. About 15% of drivers were holding one (no handsfree in this counting). You have to watch out for yourselves out there.