When to use different types of bike lights

1. “See” lights - when you need to see where you are going
2. “Be seen” lights in urban settings where you need to be visible
3. Side lights - to give you all round visibility
4. Flashing lights - in daytime or at nighttime in combination with steady lights
5. Laserlight - in urban settings to eliminate the blindspot
6. Helmet lights - whenever you need extra visibility at driver’s eye level
7. Daytime lights - even with good daytime visibility, a day-flash mode will help keep you seen

See lights

“See” lights allow you to see where you are going in the dark. If your ride takes you out of the town or city on unlit or poorly lit roads, you’ll need a strong, bright front light just to be able to see where you are going. You’ll want to pick up any potholes or debris on the road ahead with plenty of time to be able to react.

These lights will also make you visible to other road users, but the powerful light often comes with a compromise: they can be bigger and bulkier with shorter battery life. A poorly designed or poorly aimed/mounted light can also be so bright that it dazzles other road users. So it’s really important to make sure your lights are set up correctly to give you maximum visibility of the road ahead while not creating a danger to other road users.

Be seen lights

 The purpose of “Be seen” lights is to make you visible to other road users. If you’re riding in the city, you’ll be able to see where you are from street lighting - so your lights’ primary function is to make sure others see you. It’s important that your lights let you be seen from the front and behind. You should ride with a white light on the front and a red light on the rear.

Side lights

Side visibility is also important on your bike. In an urban setting vehicles are coming from all different directions and you need to be seen side on at junctions. It’s possible to buy side lights for your bike that clip to your frame. You can also find lights that attach to your wheel and light up as the tires turn.

Flashing lights

A flashing light on your bike is an increasingly popular option for “Be seen” lights. Different lights have different flashing patterns, but all work because the flash attracts the eye of other road users and makes you easier to spot. You can use a flashing light daytime or nighttime. As there is some research that shows that a flashing light makes it more difficult for drivers to judge how far you are away, at nighttime it’s a good idea to combine a steady light with a secondary flashing light, for example on your bag or helmet.  

Remember to check the legality of flashing lights in your country or territory - they aren’t allowed everywhere. 

Laserlight

A laser bike light uses a laser to project an image onto the road. 

Helmet lights

A helmet light is a small, lightweight light which clips to the front, top or back of your helmet. These lights provide a secondary point of visibility closer to a driver’s eye level and also help road users distinguish your head movements. You should always use a helmet light in addition to the main lights attached to your bike, and not as the only light you have.

Daytime lights

Most people know that they need bike lights at night when it’s dark, but did you know that using a light during the day can also improve your visibility?

A light with Day flash mode, uses a very bright flash to catch the eye of drivers who might have missed you. A day flash mode is brighter than flashing mode designed for nighttime use, since the contrast needs to be greater to be effective. The flashing pattern is also different - instead of a HIGH-LOW-HIGH sequence, the light uses ON-OFF-ON.

What You Need to Know About Bike Lights

Solid Versus Flashing Lights

Most lights have several settings, ranging from solid to flashing to pulsing, often at various speeds. A solid white light is hands down a cyclist’s best option for seeing the road ahead at night. It’s also excellent for making you visible to other road users, while not distracting others and delivering constant information about your location. “Continuous lighting sources are less jarring than blinking lights,” says Ryan Young, youth-programs coordinator at the Cascade Bicycle Club. 

On the other hand, research shows that solid light isn’t as good at capturing our attention, making it a less optimal setting for a taillight or a be-seen headlight. According to Heather Nenov, an ophthalmologist from Stein Optometric Center, light entering the eye at a consistent brightness activates photoreceptors at the back of the eye. However, when light enters the eye in flashes, it activates those photoreceptors repeatedly and can activate more of them. “Think car-brake lights,” she says. “It’s the contrast that catches our attention more than if they were just on continuously.” 

The Optimal Setup

At Night

You should always run a minimum of two lights on your bike while riding at night—a front-facing light to illuminate the road ahead and a rear-facing taillight so drivers behind can see you. Your front light should be white, bright enough for you to see any upcoming obstacles, and set to the solid-beam option. Most good nighttime front lights range from 250 to 2,000 lumens (in comparison, a car headlight is usually 700 to 1,200 lumens). “For a light that is designed to see, many riders are comfortable mountain-biking at about 700 lumens, but 1,000 lumens is what I really start recommending as the minimum,” says Alex Applegate, the marketing manager at Bontrager, a maker of cycling apparel and accessories like lights. “If you are commuting on the open road and using the light to see, I would use the same recommendation. In a city setting with more ambient light, you can get by with less.”

Your rear light should be red and ideally pulsing, and it only needs to be bright enough for other cars to see you. Your rear light only needs to be 50 to 100 lumens—much less powerful than your front light. Remember: it doesn’t need to help you see, just be seen.

It’s also not just about lumens. “Lumens are a measure of total light output,” says Applegate. “The higher the number, the more total light is emitted. But it’s not as easy as more lumens equals more visibility—optics and focus play a huge part in where the light goes and how far you can see it or be seen while using it. Think about a regular lightbulb: it’s pretty bright up close, but from a distance, not very visible. To be visible from a meaningful distance, especially during the day, the focus and optics of a light are just as important as lumens.”

During the Day

Daytime running lights are not legally required, but research sponsored by Trek/Bontrager found that the accident rate for cyclists with constant permanent running lights is 19 percent lower than for cyclists without lights. During sunny hours, getting a driver’s attention requires a more powerful light source or flashing pattern. Daytime running lights, like the Bontrager Flare RT, have a different, more concentrated beam pattern for higher visibility in bright light. But if you don’t have a dedicated daytime light, switch both your front-facing and rear-facing lights to the brightest setting available, and turn them to pulsing or flashing mode. 

Light Positioning

No matter what mode your light is in, it’s useless if it isn’t placed where drivers can see it. While mounting lights on highly visible body parts—like your head (via your helmet)—is all well and good, Cascade Bicycle Club’s Ryan says you should only do this for your headlight if you already have a light also mounted on your handlebars. “If your only front-facing light is on your helmet, you can always see where you are looking,” he says. “But if you turn your head, the traffic opposite your direction of travel will no longer see your light [or potentially you].” If you attach your taillight to your seatpost or seatstays, be sure it’s not being obstructed by a saddlebag or your tire. As with any new piece of gear, get familiar with your lights before taking them out on the road.

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