Why should I use a mirror?

Question

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?

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

I am an Audax club member and so am mostly riding on high speed country roads - B class highways in the main.

Firstly I would say that just as a good driver should be using a 'system of car control' to avoid collisions, then in exactly they same manner, and with exactly the same system, so should a bike rider. And this would be whether in the city or the country. Bike riders should be even more diligent in using such a system because if they are hit they have absolutely no protection - just a foam helmet!

The well recognised 'system of car control' emphasises the importance of knowing what is all around - both in front, and behind, on a regular 10 to 12 second basis. That is, the rear-view mirror should be checked about every 10 to 12 seconds in a car, and whenever a hazard is first detected. I do the same on my bike - both in city and country riding.

I use a good sized mirror that is sturdy, does not vibrate on coarse metal roads, or get pushed around by the wind, and is either flat or only very slightly curved.

The mirror should be able to see a silver or white car at least 300m away. They are the hardest to see because they can blend in with the clouds. A curved mirror is not up to the job. And there are an awful lot of silver cars out there! Although a curved mirror, not too small or too curved, is ideal for the city.

I have also developed a particular system I call 'trigger points' - points in the ride that trigger me to check my mirror, over and above the regular 10 - 12 second checks.

These trigger points are due to three hazards that are of particular relevance to riders, especially on high speed country roads, to avoid being hit by a car coming from behind. Those that overtake when it is not safe to do so.

The three situations, or hazards, that cause me to instantly check the mirror are

a) an ONCOMING CAR,

b) a BLIND CORNER less than 200m ahead (or less than 100m - 150m behind),or

c) a BLIND CREST less than 200m ahead (or less than 100 - 150m behind).

I have observed that

a) in the situation of an on-coming car, and another car coming up from behind, most (I estimate 80% to 90% of drivers) do not do the right thing and slow down behind the bike, and wait until the oncoming car has passed before overtaking.

b) and c) - In the case of blind corners and crests - Most drivers just hope that no car will suddenly appear from around that blind corner, or over that crest, while they are on the wrong side of the road.

I do not take the "bugger you, I'm all right" approach.

That is, just keep riding along hoping that if a car does approach from behind, that the car will do the right thing and slow down and wait. But if they don't, and then have an accident - a head-on-collison, or a side swipe with the oncoming car, or a roll over as they try to avoid that car . . . "Well it wasn't my fault - it was their fault. I was entitled to be on the road - they should have waited before overtaking . . . I never got hit, so too bad people, sorry you are injured, or dead, but at least I am still alive. And I did not break the law - you did."

Of course the bike rider will also be at risk in these situations, whether by the overtaking car suddenly realising they are in trouble and just trying to miss the rider by a few cm, or actually deciding that they have to save their own neck by wiping out the cyclist!

By doing that mirror check when triggered, in that 200m 'danger zone' before those three particular hazards, then I have plenty of time to move right over to the left of the bitumen so that any overtaking car can safely pass without having to cross the centre line.

Or if the sealed surface is not wide enough, I have plenty of time to slow down to a safe speed so that I can go onto the unsealed side of the road. Either stopping if it is unsafe for my tyres, or continuing riding slowly until the cars have passed, and I check the mirror, plus head turn, before going back to the bitumen.

All this is just exactly what good car drivers do anyway - use the same system.

1. • Always scanning for hazards - both in front, to the sides and BEHIND
2. • If a hazard is observed - CHECK the MIRROR
3. • Now, knowing the full situation, both in front and behind - decide on a course of action (plan of action)
4. • If the course of action requires a change of direction (e.g. moving over to the left) - then signal
5. • Put the plan into action

Most times when the three situations above occur, on checking the mirror I see that no cars are approaching from behind (close enough to be a danger), and so there is no action required.

On a typical 200km Audax ride I would say that I average 5 times where I have had to leave the bitumen. And on the other occasions I have just had to move over the white line on the left, to near the edge of the sealed verge. So I have left plenty of room for the overtaking car to not have to cross the centre line. Or maybe just by a small amount.

This well rehearsed system has possibly saved my life on several occasions.

The last one, about a year ago, was when I was daydreaming actually, enjoying a nice downhill run on a narrow road. Suddenly I heard the roar of a semi speeding down from behind! (I really should have spotted the truck earlier, either by the regular 10s check, or by noticing that about 200m ahead, at the bottom of the hill there was a blind corner to the right. A trigger point!)

Well, as the driver 'put the pedal to the metal', the roar of the engine woke me up, so I instantly checked ahead - a blind corner! I just had enough time to use the brakes, slow a bit, and go onto the dirt and stop.

Then I saw a large 4x4 come from around that corner, quite fast, and a lot less than 200m away by now! Just a second or so after that, the semi sped past me with his string of huge wheels on top of the white line. The same white line that I had to my left just a few seconds before!

So it would have been either myself smashed to pulp, or that semi would have hit that 4x4, or hopefully the 4x4 driver, being alert to the problem, being able to leave the road without a roll-over!

But by me being out of the way, right off the bitumen in this case, I had taken charge of the situation, and so I was not depending on others to do the right thing, or be alert and skilled enough to do the right thing.

I had not only possibly saved my own life, but at the same time, by taking myself 'out of the picture', I was not putting other lives in danger either.

It is a good feeling to be in control, and not be at the mercy of others.

And as a result I don't feel at great risk, or in great danger, when riding out there on the highways with cars and trucks doing up to 110km/hr and sometimes more.

Provided I stay alert and stick to my system - the 'system of bike control'.

To put all this in a nutshell -

Riders need eyes in the back of their heads - No, riders need a mirror.

A rider without a mirror is a rider half blind.

A rider with a mirror also needs a plan.

A mirror without a plan is a mirror wasted.

Answer 5

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.

Answer 6

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.

Answer 7

I thought mirrors were daft - having a spikey thing up by my eyes was not an attractive proposition. A simple shoulder check works fine on an upright bike, and my ears work fine too.

Later I started riding a recumbent. These make shoulder checks damn-near impossible, so mirrors are required.

The main point of a mirror is that you can scan it much more often. I'd normally only do a shoulder check when preparing to do a manoever like a cross-road turn or change to a turning bay, or if I saw something ahead that could need avoiding so I want to know what else is in my vicinity.

With the mirror, I can often pick up another cyclist approaching from behind. Without, I can be surprised by a rider zooming past with no warning.

The most telling point - When I broke a mirror and took it off, I found myself looking where the mirror had been. It was hard to un-train my brain and return to the blissful world of ignorance of "what is behind you... is not important!"

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I tried a blackburn stick-on mirror on the road-side of my helmet, and it was moderately effective. Downsides:

• I had to make an effort to focus on the image with only the eye nearest the centerline. The other eye couldn't see the mirror because my nose is in the way.

• There's a significant sector of visibility that was blocked by the mirror. I ended up fiddling the adjustment so the mirror rode above my normal line of sight, but there's still stuff that is utterly hidden when at the wrong angle.

• Car headlights are awful bright in the mirror. Might not be quite such a problem on an upright bike, but on the `bent I'm closer to their main beams

• But the biggest drawback was how useless the image was. Firstly in terms of sector covered, I could not reliably see cars approaching from behind. So I could check, then shoulder check, and still not see a car that was normally placed behind and to the centerline side of my bike. I ended up with a technique of swinging my head ~40 degrees to try and see more behind, which was counter-intuitive and distracting.

• Secondly the roads in my country have a lot of chipseal, which is hard chipped rock embedded in tar. Its a cheap and durable road surface, but it buzzes badly. This makes the little mirror bobble up and down and fuzzes out the reflection. Seriously not usable on chipseal. On smooth asphalt or bitumen or tarmac or even nice smooth concrete, the helmet mirror would be better.

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I have also tried some janky-plastic cheap handlebar mirrors. They last a month or so and then some part tends to crack. They seem to buzz and vibrate in the same way as the helmet mirror too, and cheap ones tend to have ridiculously poor reflective surfaces.

You need a glass mirror, not a plastic mirror.

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However its not all bad news. I bought a cheap motorbike wing mirror and its been stunningly good.

Downside - its got some mass to it. It easily weighs 4-5x as much as a cheap plastic mirror.

Upside - that mass seems to be what reduces the buzzing. It is fully useable on chipseal roads where the helmet mirror was useless.

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Remember all mirrors will suffer in the dark, and performance will drop off when they get wet with rain or dirty. Even cold mornings can make them fog up, decreasing reflections.

So I had a vague plan to mount a small ~3" TV screen to my `bent's bars, and connect an analogue reversing camera out behind the seat. This hasn't eventuated because none of the screens had a useful brightness adjustment, and there are a very limited number of completely waterproof units available. I carry a USB battery pack already, and it has a 12V output to power the screen/camera.

Answer 8

Riding recumbents I can not easily look behind me and need a mirror to actually see what is going rather than rely on hearing.

When riding an upright bike I do not usually use my mirror (most bikes have one mounted on the bike, I do have a glasses mounted mirror) and I miss it the first few days.
Yes, you listen and you do look behind you when you are about to cross into the line of other traffic but with a mirror you know much more and it is easier to get that information.

Where I get the most use out of the mirror is riding in the dark.
The lights of a car or even a bike behind you stand out even when you do not look into your mirror.

Unlike @Tom I value my mirror most where I have to mix with cars, less so on cycle paths and roads without much traffic.

(For those who want to know more about looking behind you on a bike, this site is reviewing some and I got my current mirror on an international selling site after reading the review here. I am not connected to this site in any way.)

Answer 9

Get a large diameter helmet mirror: I have been using the Safe Zone Mirror (https://www.efficientvelo.com/home/safezone/) for three years now while riding mostly on the Blue Ridge Parkway in North Carolina.

It is without question the finest piece of bicycle kit I own. When I turn my head slightly and they see the Safe Zone oversize (57mm diameter) mirror move, "hesitant" motorists, fearful of my swerving into them as they pass, are assured that I see them clearly and will hold my line. They then pass with confidence.

Also, when I enter Parkway overlooks, all I have to do is turn my head slightly to see, with perfect clarity, two full lanes behind me - which allows safe exits at the same speeds I entered them.

Having to look back over my shoulder as the result of using a lesser (smaller) mirror would not only be dangerous but is well nigh impossible for this 68 year old neck.

Answer 10

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.

Answer 11

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.

Answer 12

I'd like to expand a bit on the hearing aspect others brought up.

Yes, a cyclist can hear cars behind them coming on (much better than car drivers), but that is a bit limited in judging how many / how fast, doesn't really work on busy in-town roads with constant noise. AND it fails once you have electric or hybrid cars behind you, possibly on whisper asphalt.

A reason against bike mounted mirrors I'd add is, I suspect they are one of the first targets of vandalism, like generator driven lamps you'll have a much harder time parking unsupervised.

PS: I would've started the discussion with "same as with cars". (I think that's a good starting point when discussing a feature for bikes that are already spread on cars)

What are the advantages of hydraulic breaks over cable breaks: the same reasons for which cars use them. Why should I use transmissions on bikes: for the same reasons cars use them

Answer 13

You should use a mirror as much as you use training wheels. A mirror does not compensate for poor bike handling skills. Stay off of the road if you cannot hold a straight line whilst turning your head.

1. Your field of vision is far greater if you turn your head.
2. A helmet attached mirror can be a vector for eye damage as a result of a crash.
3. Handlebar attached mirrors are obtrusive and can act as a hook for anything nearby.
4. If you can keep a straight line while riding there should be no concern for a passing vehicle.