Bike lights allow you to see the road in the dark and be more visible to other road users. However, lighting needs vary depending on the type of terrain. The lit streets of Paris, the dark roads of the Île-de-France region, and night-time mountain bike trails require different levels of power, range, and beam patterns.
To choose the right bike light, it is important not to focus solely on the number of lumens. Speed, optics, battery life, lighting modes, water resistance, and the mounting system also play their roles. The experts at Routes and Roads explain how to choose a bike light for the city, the road, gravel, and mountain biking, and which characteristics influence performance.
Table of contents:
Legal requirements for bike lights in France
Front and rear lights
Lumens and lux of a bike light
How many lumens for a bike light
Bike light beam pattern
Lighting modes
Battery and runtime
Water resistance
Mounting a bike light
How to choose a bike light for the city, road, gravel, and MTB
Conclusion
Legal requirements for bike lights in France
In France, bicycles must be equipped with a non-dazzling white or yellow light at the front and a non-flashing red light at the rear when riding at night or when visibility is poor. The primary rear light must be non-flashing. The bike must also be equipped with a white front reflector, a red rear reflector, orange pedal reflectors, and orange side reflectors. The latter are not mandatory if the tires are equipped with reflective sidewalls.
Outside urban areas, at night or when visibility is insufficient, the cyclist and their passenger must wear a certified high-visibility vest. This is important for evening road and gravel rides in the Île-de-France region and other parts of France.
French regulations do not set a single brightness value in lumens suitable for all types of routes. Therefore, the power and characteristics of bike lights should be chosen based on speed, road lighting, and riding conditions.
Lights make the cyclist more visible to other road users
Front and rear lights
Modern bike lighting can be divided into front and rear lights. They serve different purposes, so you should not compare them solely based on their power.
The front light is primarily used to illuminate the road. Models with a controlled beam and moderate power are suitable for city riding. For unlit country roads and trails, requirements for range, beam width, and maximum power are higher.
The rear light is used to make the bike visible. Here, lumens are less important than the visibility angle, side visibility, and the presence of an easy-to-see red light. For example, the CLUXX Visioner 25 model uses a Fisheye lens providing a wide viewing angle. This keeps the light clearly visible not only directly behind the bike but also from the sides, which is useful at intersections and in dense urban traffic.
Beam shape and optics strongly influence the distribution of the luminous flux:
1. wide beam; 2. focused beam
Lumens and lux of a bike light
The luminous flux of most bike lights is expressed in lumens (lm). The higher the number of lumens, the more powerful the lamp. Some technical sheets also indicate another unit: lux (lx).
Lumens and lux describe two different characteristics of light. Lumen indicates the total luminous flux, while lux measures the amount of light reaching a given surface. One lux corresponds to one lumen spread over an area of one square meter.
Imagine having to spread the same teaspoon of jam on a small cracker and then on a large slice of toast. The amount of jam remains the same, but the layer will be thicker on the cracker. Light works in a similar way: the same luminous flux can be concentrated on a small area or spread over a wider zone of the road.
Therefore, it is impossible to determine the actual illumination of the road based on the number of lumens alone. One light might produce a wide, diffused beam, while another, with the same luminous flux, concentrates more light in its central zone and illuminates further ahead.
When the manufacturer provides information on range, beam shape, or illumination in lux, these characteristics allow for a better understanding of the light's performance on the road.
How many lumens for a bike light
The appropriate power depends on speed and route lighting. The values below serve as practical guidelines: two lights displaying the same number of lumens can offer different performances due to their lens, reflector, and beam shape.
-
100 to 400 lm — daytime visibility and well-lit streets. The lower part of this range is mainly suitable for signaling the cyclist's presence. More powerful models also illuminate the space in front of the bike. For daily commutes on Paris’s lit streets, this range is often sufficient.
-
400 to 800 lm — suburbs, parks, and poorly lit streets. This power already allows for proper distinction of road surfaces, turns, and obstacles. For example, the CLUXX Lumia 500 offers 500 lm and is suitable for routes where street lighting is insufficient.
-
800 to 1200 lm — unlit roads. This range is suitable for night-time road rides and gravel paths. As speed increases, the beam’s range becomes just as important as the power.
-
1000 lm and more — night-time mountain biking. On a technical trail, you need to be able to distinguish the center of the path, its edges, rocks, roots, and turns. A powerful and sufficiently wide beam is therefore necessary.
The CLUXX Lumia range demonstrates these differences very well. The Lumia 200 model offers 200 lm and is primarily aimed at urban commutes. With its 500 lm output, the Lumia 500 is suitable for poorly lit streets and suburban routes. Finally, the Lumia 1200 reaches 1200 lm and is designed for dark roads and off-roading.
For night rides, a front light of at least 800 lumens is required
Also consider the optics: they determine the distance and width over which the advertised luminous flux is distributed. On the CLUXX Lumia 1200, an anti-dazzle lens produces a directional beam and helps reduce the risk of blinding oncoming drivers and pedestrians.
Such high power is not necessary for a rear light. Here, visibility, viewing angle, side lighting, and battery life are more important. For example, the CLUXX Visioner 50 remembers the last selected mode and offers a long runtime, which is practical for regular use.
Bike light beam pattern
The lens and reflector determine how the light is distributed in front of the bike. In addition to power, you should therefore evaluate the width of the illuminated area, the range, and the presence of a clean upper cut-off line.
In the city, a directional beam is particularly practical: it illuminates the road in front of the bike while limiting light projected above the road. In the heavy traffic of Paris, this optic allows you to see obstacles better without bothering oncoming motorists, cyclists, and pedestrians.
On the unlit roads of the Île-de-France region, range becomes more important. The higher the speed, the sooner the cyclist needs to spot a pothole, a turn, or an obstacle.
For mountain biking, a wider beam is required. It allows you to check not only the space in front of the wheel but also the edges of the trail, the terrain, and the turns. For technical night rides, it is sometimes useful to add a helmet light to direct light in the same direction as your gaze.
The CLUXX Lumia 1200 model produces a wide, long-range light beam
Lighting modes
Multiple power levels allow you to adapt the lighting to the route and manage battery consumption more efficiently.
Full power mode is used on the darkest sections, at high speeds, or when long range is needed. Medium mode is suitable for most night rides. Eco mode is practical on lit sections and allows for a significant increase in battery life.
Some models offer a Boost/Turbo mode, which allows for short-term operation at maximum power. There is also a step-down mode: the electronics automatically reduce power if the light heats up or after a certain period of operation. The maximum power indicated on the datasheet does not always mean the light can maintain it continuously.
Some models also offer automatic functions. A light sensor measures the ambient light intensity to adjust the power, while a rear light equipped with an accelerometer can increase its intensity during braking.
The chosen mode has a direct influence on battery life. Therefore, compare not only the advertised maximum runtime but also the runtime at the power level you will use most often.
Different lighting modes allow you to better adapt to light conditions
Battery and runtime
Most modern bike lights operate with an integrated or external battery. This solution is practical for regular commuting: the light can be recharged via USB or USB-C, while an indicator allows you to check the remaining charge level.
For example, the CLUXX Lumia 1200 model is equipped with a 3200 mAh battery and a USB-C charging port. It can also serve as a power bank for small devices, which can be useful on long rides when you need to charge a bike computer or a smartphone.
Lights with disposable batteries are practical for trips without regular access to an electrical outlet: you simply replace discharged batteries with a fresh set.
Some powerful lights can be equipped with an external battery. This offers extra capacity without requiring the installation of a bulky battery directly into the light housing. This solution is particularly practical for long night rides and mountain biking.
To choose your model, consider the runtime in the mode you need and provide a safety margin. In cold weather, the actual battery life may decrease.
Before each ride, check that all lights are charged
Water resistance
Rain, water spray, and mud are frequent companions of urban, gravel, and mountain bike rides. It is therefore useful to check the IP rating of the light.
The following levels are the most common for bike lights:
-
IPX4 — protection against water splashes from all directions. For standard commutes in the rain, this level is generally sufficient.
-
IPX5 — protection against water jets. Suitable for regular use on wet roads and in bad weather.
-
IPX6 — protection against more powerful water jets.
-
IPX7 — protection against temporary immersion under standardized test conditions.
For daily city cycling in Paris and rides in the Île-de-France region, IPX4 is usually sufficient to handle rain and spray. For regular use in bad weather, gravel, and mountain biking, an IPX5 rating or higher is more suitable. The CLUXX lights in the range presented here benefit from IPX5 protection.
Rain, water spray, and mud accompany cyclists during the mid-season
Mounting a bike light
The mounting system influences ease of use and beam stability.
In the city, quick-release mounts are very practical. For example, the CLUXX Lumia 200 can be quickly removed after parking the bike and taken with you. This system is particularly well-suited for daily urban commutes when the bike often needs to be left on the street.
For larger and more powerful lights, as well as for gravel and mountain biking, it is better to opt for more rigid mounts. They move less due to vibrations and maintain their set angle on irregular roads.
Also, remember to check the available space on the handlebars. A bike computer, bell, bag, or action camera can interfere with installing the light. On road and gravel bikes, under-computer mounts or integrated brackets are convenient when compatible with the chosen light.
How to choose bike lighting for city, road, gravel, and mountain biking
For daily commutes in Paris, a compact front light with moderate power and a highly visible red rear light are generally sufficient. If a large part of the route is on lit streets, a well-controlled beam and a quick-release mount are more important than maximum power.
For suburban commuting and rides in the Île-de-France region, a more powerful light with good range is useful. When the route alternates between lit streets, parks, and dark roads, a model offering multiple power levels is practical.
For night road rides, range, mount stability, and sufficient battery life are essential. For gravel, you also need to be able to clearly distinguish irregularities and road edges. For night mountain biking, a powerful and wide beam is necessary to clearly distinguish terrain features on technical sections.
For suburban commutes, choose a light with a reliable and practical mount
If the same bike is used both in the city and for routes outside urban areas, it is best to choose a light offering several power levels: the medium mode can be used on lit streets and the full power mode on dark sections.
Conclusion
A good bike light should be chosen based on your actual route, not the advertised maximum lumen count. Power represents only one part of its performance: the beam, range, battery life, water resistance, and mount reliability are just as important.
Routes and Roads offers a wide selection of CLUXX, Knog, BBB, and other brand bike lights for urban commutes in Paris, rides in the Île-de-France region, and road, gravel, and mountain biking in France. Our store experts can help you choose front and rear lighting based on your bike, riding conditions, and required battery life.
