Buyer’s Guide to the Best Bike Lights

Before we jump into the details, here's an interesting fact:

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    Bicycle Magazine in May 2017 reported that 80% of bicycle crashes in the United States occurred during the day.
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    According to CDC, there were over 467,000 bicycle related injuries in 2015 alone.
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    A Danish study in 2005 revealed a 30-50% reduction in crashes for cyclist using lights during the day.

When it comes to using lights while riding, be it day or night, there's no debate about it.

So the question becomes:

How do you choose the right bicycle lights?

Read on as I'll share with you what to look out.

Local Traffic Laws

In case that you're unaware, there are local laws in every state in the U.S. that regulates how bicycle lighting are used. There are also similar laws in Britain and Germany.

While each state might have a subtle difference between them, it's generally accepted that you should have both active and passive lighting on your bike.

Active lighting refers to the usage of bike lights, both a headlight and tail light.

Passive lighting refers to the presence of reflectors mounted on the bike.

You should have a front white headlight and red flashing tail light with each visible from at least 500 feet away.

Alternatively, you can also check your local bike club's website for the specific law in your respective states.

Most bike lights from reputable brands these days usually comply with the law's requirements. So let's put that aside and jump in the other important details.

Types of Riding You Do

When it comes to buying the right bike lights, you really need to ask yourself this:

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    What type of riding are you doing - tarmac, bike paths or off road?
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    What are your riding conditions - dark or lit roads, urban areas, day or night?
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    How fast do you normally ride?

For headlights, here's what we would recommend:

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    Unlit Roads: Aim for at least 700 lumens. The faster your speed is, the higher lumens you'll need. I'll explain why in the later sections.
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    Lit Roads: Minimum 500 lumens. Your light will complement the existing road lights, so you can still get away with a slightly lower lumens.
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    Off Roads: At least 1200 lumens with a focused beam. I'll explain what this means in the next section.
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    Day Time: Most lights are adequate for daytime riding as their sole purpose is for you to be seen. Look for a light with an eye catching Flash/Strobe pulse to attract attention.

For taillights, here's what I would recommend:

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    Lit and Unlit Roads: Aim for at least 50 lumens with flash or strobe mode.

Type of Bulbs

Did you notice that most bike lights in the market today use LED (Light Emitting Diodes)?

Well, there's a reason for that.

LED's are small, very energy efficient and long lasting.

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    Energy Efficient: High quality LED's are 80-90% more energy efficient than traditional light bulbs which means that you'll have longer battery life on your bike lights.​​
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    Less Heat: Up to 95% of the energy in LED's are converted to light and only around 5% is wasted as heat. Compared to traditional bulbs, which does the exact opposite - 95% into heat and 5% into light!
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    Longer Durability: LED's generally don't 'burn out' or simply fail. Overtime, they experience what industry experts call lumens depreciation, whereby its brightness gradually decreases.
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    Light Direction: LED's emit lights in a specific direction. This property of LED enables bike light manufacturers to accurately control the light beams to shine to where matters most.

Source: The Light Bulb Co, UK

Having said all the above, I don't see any reason why you should even consider non-LED bike lights!

Brightness & Lumens

Believe it or not: You don't really need a light with the highest number of lumens.

Let me tell you why below.

99% of bike light manufacturers today specify the brightness in terms of Lumens, except maybe for the German company, Busch & Muller. 

While there is nothing inherently wrong with using Lumens, there is another way to do it, which is better but less talked about.

Let me introduce you to the term Lux.

So what's a Lux and why is it better interpretation of the brightness?

Imagine the car salesperson telling you that the gas tank of the new car you're buying is 20 gallons. Would you know how far 20 gallons will last you? It depends on the engine capacity right?

What's the difference between Lumens and Lux?

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    Lumens: The unit used to represent the amount of light (aka brightness) emitted by a single source.
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    Lux: The unit used to measure the amount of light in a specific area, a certain distance from the source. In other words, it's a measure of the light's intensity.
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    Beam Angle: The coverage of the light beam in front of you. A higher beam angle results in a diffused beam (lower lux), while a lower beam angle results in a focused beam (higher lux). A beam angle of around 20-30 degrees is what you should be looking for.

Lux is the measure of the light's intensity and affects what you see on the ground.

Source: BikeExchange

Visibility Range

Like I mentioned in the section above, most light manufacturers specify the brightness in lumens. 

Take 2 different set of lights with the same amount of lumens and their visibility range could differ. It all depends on whether the light beams are narrow or wide.

A good headlight should have a minimum range of 40-50 feet where you see clearly what's on the ground in front of you.

A general rule of thumb:

For a headlight where you can clearly see 40-50 feet in front, the lumens count falls somewhere between 300 to 500 lumens. I wouldn't suggest going for anything below 300 lumens.

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    Ask yourself: How fast do you normally ride?

Let's assume for a second that you ride at 15mph and using a light with 50 feet of clear visibility.

With that, you'll have around 2.27s of reaction time. That's just about enough time for you to react to any hazards in front.

Aim to have at least 2-3 seconds of reaction time.

If you ride faster at 20mph with the same light, your reaction time reduces dramatically to 1.7s. That's just slightly longer than a blink of an eye.

Scroll through the tabs below to see how the difference in lux affects your visibility.

  • 10 Lux
  • 30 Lux
  • 50 Lux
  • 70 Lux
  • 80 Lux
  • 100 Lux
  • 150 Lux

Light Modes

Most bike headlights these days comes with at least 4 modes; the standard High, Medium, Low and Flash mode. Some goes as high as 10+ like the Knog Blinder Arc 400.

From my experience, it doesn't matter how many modes are there. It's just a numbers game for the manufacturers to look better than their competitors.

What's more important is how you use the the light modes.

There are 'To See' and 'To Be Seen' headlights.

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    To See: These are lights typically with at least 600 lumens on the High mode. For example: Cygolite Expilion 850.
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    To Be Seen: For you to be clearly visible, look for lights that is capable of between 100 to 200 lumens on Flash/Strobe mode. For example: Knog Blinder 400.

It's important that you buy headlights with Flash/Strobe function. Most headlights today have them, but for some unknown reasons, there are still lights without.

Mounting Options

The 2 most popular methods are using straps mounts and clamp mounts.

When it comes to mounting locations, there are various options available, depending on the design of the light.

The Old-Fashioned Way: On top of your handlebar.

Most bicycle lights are still designed to be mounted on top of the handlebars as its the most straightforward way.

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    Easy access to the buttons to adjust the tilt and tighten the straps
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    Crammed cockpit, especially on narrower handlebars below 40cm wide

The Pro Way: Below your GPS mount.

Some newer lights like the Bontrager Ion 800R or the Light & Motion Urban 900 are designed to be mounted on both on the handlebars and below your GPS mount with a separate mounting kit. 

It certainly looks better with this but it does come with a downside; it's harder to access the light and buttons while riding.

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    Very clean cockpit look as the light is out of your sight
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    Lights not easily accessible while you're riding

The New Way: In front of the handlebars.

Knog came up with a creative way of mounting the light which gives you the best of both worlds.

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    Clean cockpit look
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    Handlebars might be a little crammed if you're using a narrow one below 40cm

Battery Life & Capacity

You can still find bike lights using disposable alkaline batteries today in the market.

For a longer battery life and durability, I'd you go with rechargeable batteries. Most bike lights either use the Lithium Ion (Li-Ion) or Lithium Polymer (Li-Pro) batteries today as they are lighter, smaller and has much more capacity. 

There were major advancement made in lithium batteries in the past 5 years so it's just not worth the effort to keep replacing batteries, especially if you use the bike lights on a daily basis.

Source: Wikipedia.

The chart above shows why Lithium based batteries are preferred, especially for small electronic devices.

  • For the same weight, Lithium based batteries hold more charge.
  • For the same volume, Lithium based batteries hold more charge.

Size, battery capacity and battery life are relatively proportional. A longer battery life would require a larger battery capacity and hence a larger size.

That's the reason why lights with above 1000 lumens comes with a separate battery pack. Another reason is to avoid the battery overheating the entire light body.

So what's considered a good battery life?

Almost all reputable brands published their battery life based on its various light modes. Some even have battery life indicator to show you how much battery life is left for you.

Expect the headlights' battery to run for around 1.5 hours on High mode and up to 10 hours on Flash mode.

Some lights like the Cygolite Expilion 850 takes things up a notch with a user replaceable battery. You can have the option of carrying a spare if you forgot to charge.

5 Points Purchase Checklist

I've made a simple 5 Point Checklist below to guide you in your decision making process for your next set of bicycle lights.

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