Bike Lights 101: Answers to your FAQs

By Megan Flottorp

Like it or not, the days are getting shorter and the reality of winter riding is just around the corner for a lot of us. Along with the need for warmer layers, winter tyres, and a more robust maintenance routine, this is also the season when many riders realize they need to enhance their light setup. As one will quickly notice, though, there are lots of different bike lights available, suited for different needs and coming in at vastly different price points. Depending on factors like riding conditions, the type of riding, the bike of choice, and the duration of the ride, certain lights are better than others. Let’s break down some bike light FAQs to help you pick the right lights for your situation and get the most out of your budget.

What’s the difference between lights to see vs be seen?

The first question you need to ask yourself before you start shopping for bike lights is whether they’re intended to make you more visible to others or to help you see while cycling. What’s the difference, you ask? Typically, lights that are used to see with rank higher on the brightness scale, have a larger battery, and a narrower beam angle to see into the distance. Conversely, lights that are used to be seen are designed to attract attention from all angles and have features like a wide beam and side illumination. The number of lumens (see below) on a light to be seen tend to be 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 cost a bit less than lights that are intended to help you see.

Light on bicycle
There are two kinds of lights: those to see and those to be seen. © Profimedia

What’s a lumen, lux, and beam angle? Terminology help, please!

Although there’s no need to have a degree in physics to pick the right bike lights, it does help to understand a few basic terms and principles. Here are a few you’re likely to see used to describe bike lights:

• Lumen: A measure of the total quantity of visible light emitted by a source per unit of time, the number of lumens attached to a bike light represents the total amount of light emitted.

• Lux: Referring to the intensity of the light emitted on an area or surface, lux tells you how far the light will reach. If you think about lumens as representing the total amount of light emitted by a bike light, lux measures the amount of that light that gets transferred onto a surface a specific distance away. So, assuming that the number of lumens in a light remains constant, the larger the surface area, the less lux.

• Beam angle: Still with me here? The beam angle tells you how much the light spreads from the original source. An acute beam will have all its focus directly ahead while a broader beam will spread further out and create what is often referred to as a “bundle” of light. A wider bundle equals a larger beam angle and greater disbursement of light.

• Beam Type / Setting: Super, High, Full, Standard, Regular, Low, Flash, and Pulse are a few examples of beam settings that you’re likely to run into. Each brand uses their own specific terminology but they all mostly line up with the types listed above. Keep in mind that a different type of beam will also result in different energy consumption and burn time (how long a light takes to go from full charge to flat). A light may be sold as having a burn time of five hours but that is only when it is on Flash as opposed to Full. It’s a good idea to do some research here because you want to make sure you have a light that can operate at the light capacity you need for your entire ride.

Where should I put my bike lights?

With the more technical consideration out of the way, it is time to look at the practical matter of where the lights should actually go to have a maximum impact. Of course, this will depend on your unique bike but, in general, you’ll want a rear-facing light on your bike’s seat post and a front light situated in the middle of your handlebars. In addition, many saddlebags, backpacks, pannier bags and pannier racks have loops for attaching rear lights, take advantage of this feature and attach another flasher for maximum visibility.

How many lights do I need?

Regulations vary from place to place but you’ll be off to a good start if you have at least the following:

• A prominent front handlebar light, emitting white light.

• A rear light that emits red light, positioned between 35 cm and 150 cm from the ground.

• A red, rear reflector positioned between 23 cm and 90 cm from the ground.

• An amber reflector on each pedal, positioned so that one is visible to the front and rear of the bike.

Keep in mind this is the really the minimum you need to meet regulations and you’d do well to add in a few extras to maximize your safety.

Do I need to use lights during the day?

Glad you asked! The answer is yes. Despite the misguided belief that most accidents occur at night; it has actually been reported that eight out of ten cycling accidents occur while the sun is high in the sky. A recent study from Denmark concluded that the number one thing cyclists can do to keep themselves safe is be sure always to use lights during the day.

Is there such a thing as too much light?

According to regulations in most places – no. But there is a fine line between making yourself highly visible and creating a hazard by blinding other road users with your dazzling light display. In the same way that you wouldn’t cruise around town with your car lights going full beam, you don’t need to illuminate the night sky with your bike lights. The majority of lights have a variety of modes, so be sure to familiarize yourself with the setting and select something appropriate to the lighting condition you’re riding in.

Do different cycling disciplines require different lights?

Yes and no. You’ll see brands marketing lights for different disciplines, and they do differ slightly, but you probably don’t need to get a completely different set of lights just because you’ve decided to go off road. Basically, road lights are designed to function well at higher speeds, throwing out a wide, flat beam that can both light up your periphery and provide a spot beam on the road directly ahead. If you’re focused on mountain biking though, you’re probably going to want something more powerful that can help you spot hazards and points where you need to turn or brake. Although anything above 200 lumens is fine for most road-riding conditions, you might want upwards of 1000 if you’re going to be hitting some seriously hairy trails.

Cycling at night
Is there ever too much light? © Profimedia

Should I buy rechargeable lights?

Most of the bike lights you’ll find on the market today are conveniently outfitted with a USB interface for recharging. This is super handy and means that you can charge up your bike lights on your computer while you work or plug them into the wall the night before a ride. Rechargeable lights are handy and better for the environment, so there’s really no reason to opt for anything else.

What else should I look for?

For standard road cycling, you’re going to want something with a fairly broad beam angle and a nice selection of light settings. You definitely want a pulse or false mode and at least four or five other options. As mentioned above, you probably don’t need anything super bright if you’re sticking to the road, and the advantage of weaker lights is that they tend to be more lightweight and have good run times because the brightness isn’t overly high. Water resistance is another feature you’ll want to check off, as well as a something that has a user-friendly strap to mount in rubber or another flexible material.

How much should I expect to spend?

As with all things bike-related, there’s a pretty wide range of products available and they have equally divergent price points to match. Thinking about the environment you’ll be riding in and how often you’re going to use the lights will probably help you narrow down your options. For around €60 you’ll be able to get a reliable set of lights to see, whereas €20 should be enough to outfit you with adequate lights to be seen. Don’t forget to take your lights off if leaving your bike parked, though! They have a tendency to wander off if left unattended.