What kinds of rear-view mirrors work for bicyclists?
This post about rear-view mirrors is third in a series about basic equipment and skills.
Should a bicyclist use a rear-view mirror? My answer is a qualified “yes”.

CyclingSavvy Instructor Shannon Martin is wearing a large mirror, the EVT Safe Zone. She covered the non-mirror side with retroreflective smiley faces.
No law that I have been able to find requires a bicyclist to use a rear-view mirror in any North American state or province. And, unlike a motorist, a bicyclist has nothing blocking the view to the rear.
CyclingSavvy has no official position on legally optional equipment. Still, I personally feel that a rear-view mirror is a good option for a beginner, and convenient in certain situations for everyone. If you are unable to turn your head without swerving (more on this in an upcoming Beginner Skills article), you definitely need some way to see behind yourself. Hearing a vehicle approaching from behind without easily being able to check on its position is disturbing. This is a main reason that people hug the edge of the road, or avoid riding on roads.
You still need to turn your head!
With a rear-view mirror, it is convenient to take a quick glance to the rear — without turning your head, and without losing sight of what’s in front of you. Be aware, however, that all mirrors have blind spots.
Just as when changing lanes in a car, you should always turn your head to look before moving to a different road position — though you may not need to turn your head as far. There could be a car, or a bicyclist, about to pass you, in your mirror’s blind spot. So again, you should definitely learn to look behind you without swerving!
You can purchase a rear-view mirror that attaches to the handlebar, to your helmet, or to eyeglasses. Any of these takes some getting used to.
Choosing a handlebar mirror
Handlebar mirrors vary. Some mount with a clamp around the handlebar and others with an expander plug at the handlebar end. Which model works depends on the type of handlebar and the other hardware mounted on it.
Many handlebar mirrors are convex, and as the saying goes, objects are closer than they appear. Unless the mirror extends vertically like the one in the photo, it works best from a single riding position. Your body blocks the view to the opposite side of the bicycle and so, in right-side driving countries, mount the mirror on the left.
Some handlebar-mounted rear-view mirrors, including the one shown, have a ball joint and are adjustable while riding if the joint is left a little loose. That can be useful if the road curves or you change position on the bicycle.
Can a helmet or eyeglass rear-view mirror work for you?
Getting a helmet or eyeglass mirror to work well requires some attention to detail.
These are flat mirrors. You focus on the view in the mirror, not on the mirror itself. You look into it with one eye.
To varying degrees, people are either right- or left-eye dominant. If you point a finger at a distant object and alternate closing one eye, then the other, the finger still points at the distant object when the dominant eye is open. If one eye is strongly dominant, place the mirror on that side so your brain will show rather than hide the view in the mirror.

The mirror should be placed high and as far to the side as possible where the opposite eye still can see ahead. Check by closing one eye, then the other.
The mirror should be placed as far to the side as possible where the opposite eye still can see ahead. Check by closing one eye, then the other. John Allen has more detail on this topic. Larger helmet mirrors can be placed farther from the eye; only these are compatible with big hair.
The mirror should look directly to the rear or nearly so. Tilting the head can bring the road behind you into view in any riding position other than a racer’s low aerodynamic crouch. You scan right and left by turning the head while continuing to look into the mirror.
Expect to take a couple of weeks to figure out which way it is looking. This is easier if the ear, helmet strap or hair is just visible at the edge of the mirror as a point of reference.

Cyclist Jerry Campbell is right-eye dominant and wears his rear-view mirror on the right side (1982 photo). This seems strange? Brian Watson uses two mirrors!
Different rear-view mirrors have different advantages.
A helmet mirror is always there when you put on your helmet, but take care that it attaches securely. A hot melt glue gun can be useful to secure some helmet mirrors.
An eyeglass mirror is easy to misplace, unless you leave it attached to eyeglasses you use only for riding. The mirror can pull your glasses down on your nose, but it works if you wear different helmets or none, not that we recommend that!
A handlebar mirror can break if the bike falls over. No mirror is perfect, but they all can work well.
Our next article is about bells and other options to alert people with sound.
Thanks to John Allen, Pamela Murray and Karen Karabell for their assistance with this article.