Are lumen and lux the same in a bicycle light?

Bicycle lights explained

It’s necessary to pick up a bicycle light when you leave home for riding in the dark. But which bicycle light is the best? In a series of 3 blogs we take you into the world of bicycle lights. In this blog we discuss two of the most important concepts of ligths: lumen and lux.

Lumen and lux, does it sound familiar? In this blog we explain what lux and what lumen means in a bicycle light. What lumen bicycle light is the best and what does lux actually say about a light? Enter the world of bicycle lights with BBB.

BBB Cycling taking a brake

What lux means

First we have to explain the difference between two concepts: lumen and lux. Lux is the amount of light on a certain area. Most commonly, it is measured on a distance of 1 or 10 meters. When the amount of lux is measured, a brand wants the highest level and with a round bundle, that’s in the middle.

What lumen means

Lumen is the total amount of light (in all directions) emitted by that lamp. This can be produced by the LED or the lamp itself. The level of lumen from the lamp itself is lower, because the light has passed the lens, resulting in loss of light. This is the most honest value, because this is the amount of light you really see in front of your bicycle. The light always has to pass the lens, obviously. That’s why BBB always measures the amount of lumen of the light and not of the LED alone. Because that’s not an honest value on itself.

How does this look like in real development life?

Let’s take a look at the Strike lights in our range. When we developed the Strike 300 and 500 we didn’t want to just boost the amount of lumen. We wanted to create two worthy lights on their own. Below you can see the differences between the Strike 300 and Strike 500.

BBB BLS-71 Strike 300 lumen info

BBB BLS-72 Strike 500 lumen info

Both lights produce 28 lux on a distance of 10 meters. So they are evenly ‘bright’. But the Strike 500 has 200 lumen more light compared to his little brother. The Strike 500 has a broader bundle as well, resulting in 200 lumen divided over a bigger bundle.

Why didn’t we choose to use the same lens for both lights?

That’s because the human eye adapts to light. When there’s a lot of light, the pupil becomes smaller. With less light, the pupil becomes bigger. With a narrow bundle that’s very bright, the pupil becomes smaller, resulting in everything outside of your bundle becoming ‘invisible’. Because it’s outside the reach of your small pupil.

A logic question now would be to ask if every light than has to produce 28 lux on a distance of 10 meters. But that’s not the case. The keyword in developing lights is ‘balance’. As a designer of these products you constantly have to keep in mind that the light has to match the needs of each user. A helmetlight has to create more of a hotspot, while a light on your handlebar has to have a wider bundle. And a light used on the road has to be about visibility. Each light has its own specific needs and goals.