Can bike lights be too bright? Pick the BEST for Commuting


After owning several ‘to be seen’ lights, which didn’t provide sufficient light on certain segments of my commute I upgraded to the Cateye Volt 800, a really powerful and versatile commuter light, which is designed ‘to see with’. The very first day I used it to ride my bike to work I got verbally abused by another cyclist, whom I blinded with my new light. It made me think of whether bicycle lights can be too bright.

I did some further research and have fine-tuned the use of my light ever since.

Can bike lights be too bright? Bike lights (both front and rear) can appear to be too bright and blind people if not used in the proper setting and aren’t angled properly. This can be disturbing to drivers, cyclists and pedestrians, and it can be dangerous for you as well. Here’s how to avoid blinding others with your bike light.

How many lumens do you actually need?

I assume that you’re asking this question because you want to upgrade your existing to be seen lights for more powerful ‘to see with’ lights and you have some concerns. 

First off, let’s see what qualifies as a ‘to see with light’.

Lights to see with usually start at 400 lumens. At this brightness you can see the road ahead of you at a moderate pace (10-15 mph), even if the road is poorly lit or not illuminated at all. You can be confident that you won’t be hitting potholes or not notice obstacles on the road.

An 800 lumen light, like the Cateye Volt 800 is bright enough so you can ride with confidence on pitch dark roads at 20 mph or even faster.

If you ride blazing fast (25+ mph) or you ride on dark forest trails, you need an even more powerful light (1600 lumens or more). 

When you buy new lights, you should always choose based on the worst conditions that you expect to ride in throughout the year. For example:

  • If you know that you will always be riding in the city with good street lighting, then a 100 lumen ‘to be seen’ light is sufficient; buying a 1600 lumen light is an overkill.
  • If there is a 1 mile pitch dark descent on your commute, then 100 lumens will not be sufficient. Instead, go for a 800 lumen light, even if you only use it in the highest setting for that particular segment.

If you are of the opinion that ‘the brighter the better’, you will hit the limit of being a danger to others and yourself.

The problem arises when you use your highest light settings in city traffic as you use in complete darkness in the worst visibility conditions, and you have it poorly angled. In this case, your light appears too bright and becomes a source of danger.

In the following table you can find the best lights you can get for your commute based on your riding pace and the worst lighting condition you will be riding in:

 Lit urbanPoorly litPitch dark
10-15 mph100 lumens400 lumens400 lumens
15-20 mph100 lumens400 lumens800 lumens
20 – 25 mph200 lumens800 lumens800 lumens
25+ mph200 lumens800 lumens1600+ lumens

The truth about blinking lights

Blinking or flashing lights draw more attention because they stand out from the pattern of most lights. This is why it’s quite easy to spot an airplane flying in the sky and not mistake it for a star.

Are flashing bike lights legal? Legislation varies from country to country, and from state to state. Some countries explicitly allow flashing lights, some explicitly prohibit the use of flashing lights, while some say nothing about flashing vs steady lights.

If your jurisdiction allows the use of flashing lights, you should keep in mind that a very strong flashing light doesn’t only draw attention, but in dark conditions it can also be very distracting. It’s very hard to judge the distance of a flashing object at night, and it’s easy to get distracted by it, which causes some people to turn away or cover their eyes, which becomes a source of danger.

So, should you use flashing lights at all?

Flashing lights are most useful in daytime when people’s eyes are used to ambient light and the blinking doesn’t disturb. This way blinking draws attention, but it doesn’t distract. In broad daylight even those lights that emit 800 lumen bursts won’t appear to be excessively bright. 

As sunlight fades away, if there is sufficient street lighting at night, some blinking lights don’t disturb the eye. These are the typical ‘to be seen’ lights, or even ‘to see with’ lights in a low flashing mode (200 lumens or less) don’t disturb the eye. Anything more powerful than 200 lumens will dazzle some on-comers.

In the pitch dark or in very poor lighting conditions it’s best to avoid using flashing lights for several reasons. A steady 200 lumen or brighter light can easily be spotted from far away, and if it’s angled properly, it doesn’t blind anyone. Also, it doesn’t make too much sense to use a blinking light because you need to illuminate your path so you can see where you’re going, and a blinking light can become distracting to you as well. 

In complete darkness you’re best off using a steady light beam at an intensity that allows you to drive with confidence. In the dark, even a steady beam of light lets others know of your presence.

Poorly angled beam

If you have a 200+ lumen directional light, you need to pay attention to how it’s angled whether you use it in a steady on or flashing mode. If your light points up into people’s eyes you run the risk of blinding them. A poorly angled 200 lumen light can appear to be too bright if it points directly in the eye, and in a special way if it’s in flashing mode.

There are two ways to make sure that your light beam is angled properly. 

Method 1:

Check from the side how the light is mounted on your handlebar. Make sure that it’s parallel to the ground or it points slightly down. This works both day and night, but it’s harder to fine-tune the angle to get it right, because it doesn’t take into account the shape of your light beam.

Method 2: 

Mount your light on the handlebar, go to a wall and turn it on. Back away from the wall and observe the position of your light beam. Start moving backwards and adjust the light so the further you go back the more the beam moves down on the side of the wall. This is a more precise way of getting the angle right, but it can only be performed at night when it’s dark.

Change brightness and mode to suit the segment

Within the same commute there can be different conditions that require different modes. On winter mornings you may leave in pitch dark, but arrive at the office in daylight or vice versa in the evening. If you change the mode to the setting that best suits the segment you’re riding on you can:

  • optimize your light’s battery life: for example, the Cateye Volt 800 gives you about 2 hours of running time on a single charge in its steady 800 lumen mode, about 7 hours in the 200 lumen mode, and a whopping 100 hours in the strobe mode.
  • make sure that you don’t blind others, because you’re not running your lights in an unnecessarily high mode when there’s oncoming traffic.

Rear lights

Lights attached to the saddle post or the rear rack are not as powerful as some front lights, even when riding in absolute darkness, given that they are always only ‘to be seen’ lights, and not ‘to see with’ lights.

They are usually in the 30- 150 lumen range. The higher end of the spectrum can appear too bright, especially if they are in flashing mode in pitch dark. 

Although this feature isn’t present in all rear lights, some of them, like the Cateye Rapid X3, allow you to change the brightness setting. 

Take visibility to the next level

Don’t block your lights

Your lights are useful if they are charged, turned on, and not blocked when riding. Some people forget that their rear light is placed on their saddle post, and put a backpack, basket or other item on the rear rack that completely blocks the light. 

This defeats the purpose of having a rear light in the first place.

If you need to carry anything on your bike, get creative and find a place for the light, so it’s visible to others. Find a way to mount it at the end of the rack, behind the backpack or even on your helmet. 

It’s not only the lights

Of course, visibility is not only about lights. Bright colors and reflective details complete the picture. Given that they never run out of battery, they are a reliable safety backup for bike commuters.

Audible is sometimes better

Sometimes the sound of a little bell is more powerful than the light of a strong light.

Initially I thought that it didn’t look cool on my bike, so I kept it in a drawer, but only after a few days I realized how important a bell was for a commuter bike. 

When pedestrians and cyclists share the road, no amount of light is sufficient if the person isn’t facing you (about half of pedestrians). If you want to build a functional commuter bike, you must not forget about a bell.

Conclusion

Sometimes bike lights can be too bright and can blind or dazzle people. This doesn’t mean that you should not get a strong light. You should use your light in the proper setting for the segment you’re riding on and have it properly angled.

This way, you will not have any issue with blinding others, and you will always see where you’re going.

Happy Riding!

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