Bike Lights Article

Depending on where you live you inevitably will have a season or two where you may need lighting for riding your bike.  I personally would suggest using at least an emergency flasher at all times as drivers often do not see cyclists on the road.  In this knowledge base article, I will explain some of the differences between cycling lights.  There will also be a list of reviewed cycling lights at the bottom to help sift through some of the options on the market.

Factors to Consider

There are several factors to consider when purchasing a light.

  • Will I need to just be seen or to see?
  • Will I be riding roads or trails?
  • How long will I need to go before charging or changing the batteries?
  • What conditions will I likely be riding through?
  • Will I need to take the light on and off my bike often?
  • How much do I want to spend?

These are all important questions to answer when thinking about what light you need to purchase.  We will cover each of these in this article but the reviews below will be geared more towards road riding and light trail use.

Light Output

The most common measurement of light output is the Lumen.  The lumen can be thought of casually as a measure of the total “amount” of visible light in some defined beam or angle, or emitted from some source.  In more technical terms, if a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux emitted into that angle is one lumen (1 cd·1 sr = 1 lm).  Another common way of describing light output is lux. The difference between the units lumen and lux is that the lux takes into account the area over which the luminous flux is spread.


To Be Seen

Emergency lights are also best described as lights to be seen.  These would include many of the lesser expensive lights that are small and can be easily attached and removed.  Lights such as these have lesser output, multiple flashing modes, and generally have a long battery life.  I would suggest using these lights on even your daytime rides as they really are not much of a weight or aerodynamic penalty.  Nearly all rear lights fall into this category.

Light the Way

These lights are used for primarily road and light trail use when you need a light to see where you are going.  These can also be used to be seen and are bigger and brighter than the lights above.  They use more power than emergency lights and therefore, use stronger batteries or rechargeable batteries.  These lights have a more centered beam than trail lights do.  Since road riding is often at higher speeds, this narrower beam can light further up the road than broader trail lights do.  The diagram to the right will help show this comparison.  Of course, there will be exceptions to this.

Light Up Your Own Section of the World

Trail lights are the most powerful cycling lights on the market.  Some of them even can emit more power than car headlights.  This reason is because when riding trails at night you will need to see all the obstacles you need to ride over.  Trail lights generally do not have as long of a beam pattern but rather a wider one.  These lights also need to be the most durable lights of the bunch to be able to take the bumps and bruises of off-road riding.  With these attributes taken into account, trail riding lights are also most often the most expensive.

Helmet Mounted

Helmet mounted lights can be a good option for a variety of riding conditions.  Some commuter helmets have clips built to attach emergency lights while other options exist for full-power road and trail lights that can be strapped to the helmet.  Many helmet mounted lights include a front and back light giving you more visibility from all directions.  The other benefit of helmet mounted lighting is that the beam follows where you look.  If you turn your head or need to raise your light to make yourself seen better; the helmet mounted light will accomplish this.  The drawback will be the added weight to the helmet and therefore, your head.  With helmet mounted lights it is often a good idea to couple it with a front light mounted to your bike, so there is always a light pointing forward, even if you look another way.


Several years ago there were many different options for cycling light bulbs.  While many of those options are still available, the clear winner has been the LED.  A majority of lights these days is using LEDs for their cost, durability, low power needs, and brightness. As LEDs go, there are higher and lesser quality bulbs.


Durability is an important factor in what light to use.  While you may not think about it, no matter what type of riding you are going to do, the light will have to last through a variety of conditions.  Rain, wind, snow, dust, and bumps will all have an impact on the light.  It is hard to know how durable a particular light is, but I would suggest going with manufacturers with proven reputations, products with positive reviews (from YMMV Reviews or other sites), and if all else fails, price (higher cost generally means more expensive parts).

Many cycling lights also come with some sort of water resistance rating. I do not know about you but my rides are not always warm and sunny. This rating is likely to be shown as “IPX4” or “IPX7”.  these are two common ratings I have seen on the lights I have tested.  For the most part these ratings essentially mean the light can withstand rain, snow, splashing, but not submersion. So no riding into the lake no matter what you GPS says to do.

Power Types

The type of power used in a particular light depends on the type of light it is, the power output, and how long the life the manufacturer wanted.  Batteries can range from watch type batteries, AAAs, AAs, to rechargeable batteries.  There are also lights on the market that can be powered by generators built into the hub of your bike.  It is important to think about the type of riding you are going to be doing when comparing battery life and power types.  If you are planning on using the light for one hour, then you will not want a light with a 50-minute battery life.  Lights with changeable batteries often have a longer lifespan then rechargeable batteries do, but you will have to change out the batteries when they die.  This also allows you the option of bringing extra batteries along if you think you may need the extra power; this is not an option with rechargeable batteries.  Rechargeable batteries can often be charged through your computer.  They are able to be used over and over again so in the long run they will actually save you money.  Remember rechargeable batteries will also eventually not be able to hold a charge but his is normally after more than a 100+ charges.


Mounting is important if you are planning to use your lights on several bikes or want to be able to take them on and off often.  Most emergency lights are made with flexible straps that can be hooked onto a variety of locations.  Road and Trail lights are made with more sturdy mounting systems to be able to handle the extra weight and size of the lights.  Some may even have a separate battery pack that can be attached to another portion of the bike and have a cord that runs to the light.  This is common with more powerful lights as it allows them to use a larger battery.

Switches & Modes

With light switches, you want it to be easily usable while riding.  The less you have to focus on the light the more you can focus on the road ahead of you.  At the same time, the switch should be not so easily turned on that it will accidentally get turned on and then be out of power when it needs to be used.  Some cyclists like to store emergency lights in a bag until they really need them; these are the times you want to make sure your light does not turn on by accident.

Most lights have a variety of modes.  They can be split into two types: steady and flashing.  Most front lights will have a variety of steady modes such as different levels of power.  This is good to know as you can use these different levels to increase battery life and save power for times or sections when you need more output.  With rear lights, there are often different patterns of flashing lights.  These patterns are often chosen by how well they will be seen by drivers.  Patterns that continuously stimulate the eyes are better as they do not allow the driver to easily dismiss what they have seen.

Beam Pattern

Beam pattern is important depending on the type of riding you are doing.  Many lights are made so they light up the road in front of you while not shinning up into the eyes of oncoming traffic.  While this is important, beam length and width are also important.  A longer beam is often needed for faster riding such as road riding.  Since you are traveling at a faster rate of speed you will need to see and adjust to potential obstacles faster.  Generally, you have to sacrifice beam length for beam width.  The wider the beam, the shorter the length.  For slower riding or times when there will be more obstacles such as trial riding, a wider beam is normally a better option.  When trail riding you generally are not riding in a straight line as you are when on the road.  A wider beam makes it easier to see the upcoming obstacles and turns rather than a narrow and long one.    Some companies make two light options that have a long and narrow beam paired with a shorter and wider one.  While this is better than one, they normally cost a bit more.

Lights Reviewed

About the Author

I am an avid runner, cyclist, swimmer, hiker, climber, skier and many other activities that would make this list too long. I started Your Mileage May Vary Reviews in Early 2011 to combine two of my passions: sports and gear.

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