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In a comment to an answer about helmet replacement mention was made of a mirror and perhaps suggesting that a helmet was merely a good place to mount a mirror. I, hopefully humorously, suggested that a mirror user might not have much inside to need protection of a helmet ...

As someone who does a lot of miles and most of them in town, where seeing behind you is useful, I've never even considered a mirror. My preconception is that any mirror small enough to not be obtrusive or distracting would not be large enough to provide a decent view behind and, besides, I can look over my shoulder periodically and get a decent grasp for free.

So what am I not seeing; why should I use a mirror?

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up vote 19 down vote accepted

You should use a rearview mirror because:

  • It allows you to look behind you by moving just your eyes. This will help you not accidentally swerving into the traffic coming up behind you you're trying to get a look at.
  • You can (almost) look behind you and in front of you at the same time because it just takes a small eye movement rather than a huge head movement to go from looking ahead to looking behind and back.
  • It actually shows you a useful part of the road behind you despite the small size (try it)
  • All the other reasons I don't know about for which they are mandatory on motorized vehicles in (almost?) all countries all over the world.
  • They actually cost less than a good pair of socks.

You shouldn't use a rearview mirror because:

  • You'll look like a dork, same as with a helmet.
  • You're an experienced bicyclist and you know enough to stay out of danger
  • It'll add extra drag.
  • It'll add extra weight.
  • They cost more than a cup of coffee.
  • They'll screw with the sleek lines of you fixed gear machine.

I bought one after a few days of cycling in new zealand. Narrow roads, wide cattle and log trucks with sleepy drivers, some near misses, and constant warnings to be very afraid of drunk drivers made it an obvious choice. Especially because of the swerving point above, which seems aggravated when riding a bike with 20kg of luggage strapped to it uphill. I've used it on all my cycling holidays since.

Then again, I don't use a rearview mirror in city traffic in my hometown either.

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I've been too lazy to go buy one, but certainly would like to have one. It's difficult trying to dodge debris on the side of narrow roads while trying to keep an eye out for those silent electric cars sneaking up from behind. – Brian Knoblauch Sep 7 '11 at 12:36
@Brian, The only advantage of a mirror is that you don't have to move your head AS MUCH to see what's behind you. You still have to scan your head around a little to "sweep" the scene behind you and you still have to take your attention momentarily away from what is in front of you. – Angelo Sep 7 '11 at 14:13
@Angelo - depending on where the mirror is mounted they give you some amount of a rear view without any head movement. This is especially valuable if vehicles have daytime running lights--you can see them approaching in your periphery without looking ahead. This even more valuable if the vehicles are quiet (such as busses with rear-mounted engines, or hybrid vehicles) – STW Sep 7 '11 at 14:36
While it's often argued that you should just learn to turn your head to check traffic behind, few people have their heads swiveled well enough to do a really good job of that. At best, most people can check half the lane behind them, and, in the very brief time that they can safely have their head turned they get very little "feel" for, eg, how quickly traffic is approaching. Plus, in really tense situations (such as a rough, narrow road, drop-off shoulders, heavy traffic) you often can't risk turning your head at all. – Daniel R Hicks Sep 7 '11 at 15:53
One particular place where the mirror is handy is when riding in a group. You can easily keep track of how many people are behind you, how close they are, whether they are about to pass, etc. I know many will argue that voice signals should be all that's needed here, but that's only true in an ideal universe. – Daniel R Hicks Sep 7 '11 at 15:55

An argument against the use of mirrors is that when you turn your head to look behind you prior to moving across a lane of traffic for example, any drivers behind you will see your head turn and get some indication you're going to do something; whereas with a mirror, the drivers behind you don't see you checking the traffic and assume you're riding straight. A recent talk I attended about cycling safety stressed the importance of giving clear signals to other road users and the 'turning head to see behind' was one of those signals.

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This is a spurious argument: You can still turn your head around for communication even if you use a mirror. In fact, when you have a mirror, you already know exactly where to look (height of vehicle, distance away, etc.) and what exactly you want to communicate. Why be forced to combine communication with information gathering. – Dan Rosenstark Sep 7 '11 at 16:21
Why not try hand signals? Drivers often respond well to hand signals. Those who are confused by hand signals will almost certainly not understand a head gesture. Left, right, or stop. They're such simple gestures but so underutilized. – DC_CARR Sep 7 '11 at 21:34
@DC_CARR: Irony aside, I wasn't opposing the idea of hand signals, but from personal experience there are many drivers who do appear to have trouble with them. The more ways you can say "I'm moving over" the better, and eye contact can make a big difference - something a mirror doesn't do. – Skizz Sep 7 '11 at 22:01
UK Highway Code says "When passing motorcyclists and cyclists, give them plenty of room (see Rules 162-167). If they look over their shoulder it could mean that they intend to pull out, turn right or change direction." – Tom77 Sep 8 '11 at 10:26
Pointing where you're going with your arm is a much better signal than a slight head-movement. This is an official and obligatory signal for cyclists in most countries is it not? – jilles de wit Sep 9 '11 at 7:47

I use a mirror (a CycleAware Reflex) because, as others have said, it allows me to see what's coming behind me. Where I ride, the "bike lanes" are little more than poorly maintained pavement on the side of the road. So when it is safe, i.e., no traffic, I ride to the right in the roadway.

I tried bar-end mirrors and glasses-mounted mirrors, but I didn't like either one. It did take some trial and error to get the mirror correctly oriented on my helmet, but now I get a good view of the road behind me.

I've gotten fairly used to glancing back to see what's coming, so there are never any surprises. In fact, the other day in the grocery store I caught myself trying to look in my mirror to see if there were any carts behind me.

I decided long ago:

  1. I don't trust drivers, particularly the ones here in California.
  2. Riding alone, not it a group, makes me harder for drivers to see.
  3. Helmets are basically disposable, so I don't mine gluing a mirror to mine.
  4. I don't care about looking like a dork. I do that frequently enough in my regular life that time I spend on a bike is a drop in the bucket.
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+1 for #4. I'm with you there. – James Schek Sep 11 '11 at 21:38

Who doesn't take at least a passing interest in beautiful members of the opposite or even the same sex? We all do to varying degrees. Theoretically a mirror could help out with such window shopping, it could also help out getting one's hair and make-up right, much like those vanity mirrors they have in car sun-shields.

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Makes a change from crafty drafting, I guess. – Unsliced Sep 7 '11 at 14:27

I'm adding my voice to those for mirrors.

I've used a bar-end mirror for some time while riding with 1) a child trailer attached 2) a companion on another bike behind me most of the time (I was the pace setter due to the trailer). It's invaluable, and I sorely miss it while riding my other bike, with or without a trailer attached.

The model I've used: Zefal Cyclop. I've chosen this one for its small size, it is adjustable (rotates + articulated).

A little con for this bar-end mirror is that I broke one very easily because of a bike fall while parked on its side-stand. I replaced it ASAP, and became more careful afterwards to turn it upwards when stopped.

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How well a bar-end mirror (or any mirror, for that matter) works is dependent on many factors. I tried a bar-end mirror on my bike, but the combo of the narrow road bar (with the bar end at low "drop" level) combined with panniers simply didn't work. Plus there's the problem with the bar-end mirror that you must "aim" the mirror by steering, making it a hair more hazardous. Helmet mirrors, OTOH, have problems with modern helmets since they tend to stick out so far on the sides. The old hardshells worked much better with mirrors. – Daniel R Hicks Sep 8 '11 at 11:13
@Daniel In my case, I could aim by steering, but also by adjusting the mirror, which worked pretty well, despite vibrations making it 'loosen' after a while. Check Zefal's page for a closer look at the mechanism. – jv42 Sep 8 '11 at 13:43
The problem is that you only get a "keyhole" view, unless you can actively move the mirror. – Daniel R Hicks Sep 8 '11 at 15:11
Well, as I needed it, as I said, I moved either the bar or the mirror itself. I must mention this was on no cars paths and usually at moderate to very low speeds (<= 20 kph/12.5 mph) – jv42 Sep 8 '11 at 16:34
I do only maybe 20% of my riding on trails/paths and the rest on roads. – Daniel R Hicks Sep 9 '11 at 0:32

A mirror is not necessary if you're capable of swiveling your head to look around without changing the line-of-travel of the bike. This is a skill that can be learned with a modicum of experience.

The problem with using a mirror is that it is one more piece of equipment to carry and fuss with.

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How often do you swivel your head around to look? When something sudden happens and you have to swerve, you have to already KNOW what's behind you (which is why you always check your rear-view mirror in a car, even when nothing is going on). At that point, there is no time to swivel your head around (and back) and make a decision. Mirrors help because you can check them 6 times a minute with just a rapid eye movement. – Dan Rosenstark Sep 7 '11 at 16:23
@yar, I have used an eyeglass-mounted mirror before. It just isn't worth the hassle. And anyway, the mirror does NOT give a complete view of what is behind you. You MUST scan your head a little to REALLY see what's behind. I'm not saying that a mirror is a bad thing, just that it is not necessary for folks who can swivel their heads while holding a line. – Angelo Sep 7 '11 at 16:51
I have two problems with the eyeglass mirror: First, it doesn't stick out far enough, and second, it moves as your glasses slide around, and my glasses slide around quite a bit, even with a Croakie. – Daniel R Hicks Sep 8 '11 at 11:15

I've spent at least 15 years riding in the city without a mirror and bought a simple helmet mounted convex one last year. While at first it seemed completely redundant and hard to use, I find it quite handy now.

It definitely takes some practice to position the mirror so that you can quickly glance at it, focus your eyes and turn your head a little to "pan" around to see what's behind you.

Since I've had so much experience without it, I also found that I could hear cars and judge their position sooner and more easily than using the mirror. This probably would not be the case for a beginner rider.

Where it is very handy is for avoiding being surprised by approaching cyclists and judging their intentions since they are largely silent, and even the ones that call out a signal may do so late or mumble.

So, I actually find it pretty useless on the streets, but on bike paths it's quite handy.

It really can't hurt to have it there (though it can be an annoying source of reflections when the sun is low), and if it helps just once it's probably worth it.

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