Unlike a car where the choice of lights are barely a consideration, a cyclist must carefully choose the right best road bikes lights depending on the riding conditions, the type of riding, the bike of choice and the duration of the ride.
With this helpful guide, we aim to outline the terminology you need to know, the difference between lights to see with versus ones to be seen, the unique requirements of road riding, mountain biking, and commuting, and also give you an idea of how far your budget will stretch.
Lights to be seen vs Lights to see
There is one fundamental question you need to ask when shopping for lights – do I need my lights to ‘be seen’ or ‘to see’ with?
Lights that are used to see with will have increased brightness, a larger battery to power the brighter light, and a narrow beam angle to see into the distance. Lights that are used to be seen will have a focus on being seen from more angles, with features such as a wide beam and side illumination. The number of lumens is generally lower as the priority isn’t to see far into the distance. As a result, be seen lights are often lighter, with smaller batteries, fewer lumens, wide beam angles and lower cost than lights that are used to see with.
And while you may think you only need lights in the dark, a reported eight out of ten cycling accidents occurring during the day, and the use of lights during the day is the number one thing cyclists can do to make themselves safer according to a Denmark-based study. According to Bontrager’s white paper on the matter, to classify a light as one suited to daytime use, it needs focused optics, an interruptive flash pattern, and a visible distance during the day of at least 400 meters. Bontrager claims – “Using a flashing tail light in the day makes you 2.4x more noticeable than with no lights at all and 1.4x than in steady mode.”
Lumen: The number of lumens represents the total amount of light emitted by a given source.
Lux: Lux is the measure of the intensity of light on an area or surface, most commonly this is measured at a distance of between one and ten metres. If you imagine that ‘lumens’ represents the total amount of light emitted by a bike light, lux measures the amount of that light that gets transferred onto a surface a distance away. So assuming that the number of lumens in a light remains constant, the larger the surface area, the less lux. However, the opposite is also true. A light with the same amount of lumens will have a greater lux-value if the surface area the beam is directed at is smaller. This aspect is particularly important as we discuss beam angle and bundle later in this article, and which light is best for different cycling disciplines.
Beam angle: The beam angle gives an indication of how much the light spreads from the original source. Some lights have an acute beam angle that focuses directly ahead (increasing a light’s lux), while others have a broader beam angle that spreads (decreasing a light’s lux). This is sometimes referred to as a ‘bundle’. The wider the bundle, the broader the beam angle and disbursement of light; the smaller the bundle, the narrower the beam angle and light disbursement.
Beam Type / Setting: Super, High, Full, Standard, Regular, Low, Flash, and Pulse are just some of the various beam types or settings you may encounter. Brands describe the kind of beam exiting the light their own way, and so it pays to delve a little deeper into these descriptive terms to find out what each name represents and how that impacts on run time. For example, a light may promote it has a five hour run time (sometimes called burn time), but that may be on ‘flash’ mode which emits a small amount of light intermittently, whereas the same light on ‘full’ or ‘high’ that is emitting light invariably may only last for 30 minutes.
Burn time: How long a light takes to go from full charge to flat on a given beam type or setting.
Road riding and off-road riding require different approaches to lights. Road riding generally is done in straight lines with few obstacles along the way, so a light that directs its focus straight ahead is ideal. Conversely, off-road riding requires a broader light bundle to illuminate the area directly around you to see tree roots, rocks, and other obstacles.
The primary purpose of having a light on the road is visibility, so that should be first on your list. Does it increase your visibility and enable drivers and pedestrians to see you? To do this, a light needs to have a broad enough beam to be seen from the side and acute angles, as well as front on.
Australian Road Rules give a clear indication of the minimum lights requirements when riding a bike at night. If you are riding a bicycle at night, you must have a white light (flashing or steady) on the front, a red light (flashing or steady) on the back and a red reflector on the back. The lights must be visible from 200m and the reflector visible from 50m. The 200m rule is the critical requirement to look for when purchasing lights, regardless of whether they are to see or be seen.
Once you’ve established the light provides sufficient visibility, factors such as price, size, weight, durability and the intended use will all play a role in choosing the right light.
It worth ensuring that you don’t always get sucked into the lumens per dollar decision, a light’s optical design – lens, LED’s, beam angles – are as influential on brightness as the lumen number. We suggest that whichever light you choose needs to fit with the type of riding you do first and foremost. In addition to those essential items, things like good water resistance, USB rechargeability, and quick release mounts are features worth searching for.
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