What you need to know about bike lights

What you need to know about bike lights

What you need to know about bike lights January 4, 2024Leave a comment

What you need to know about bike lights

According to the National Highway Traffic Safety Administration, more bicycle fatalities occur between 6 p.m. and 9 p.m. than any other time of day – nearly 40 percent. You can probably guess why.

While no amount of safety gear can protect you from distracted or drunk drivers, staying visible on the road at night can help you avoid being hit by an attentive driver. One of the most effective ways to ensure this? Bike lights. They’re not just for night-time cycling, either: although not required by law, daytime running lights can also help to attract the attention of motorists in broad daylight (more on that later).

Bike lights fall into two categories: visible lights and visible lights. “Visible lights are bright enough so that nearby motorists or pedestrians can see you,” says Andrew Ibanez, a sales representative for bike light company Cygolite. “Vision lights are much brighter and illuminate the road or trail ahead.” There is clearly some crossover between the two.

Constant Lights vs. Flashing Lights
Most lights come in a variety of settings, from constant to flashing to pulsing, usually at different speeds. A steady white light is undoubtedly the best option for cyclists to see the road ahead at night. It’s also perfect for allowing other road users to see you without distracting others and providing constant information about your location. “Continuous light sources are less harsh than flashing light sources,” says Ryan Young, youth programme coordinator for the Cascade Cycling Club.

On the other hand, studies have shown that solid light is less likely to grab our attention, so it’s not the best setup for tail lights or visible headlights. Heather Nenov, MD, an ophthalmologist at Stein Optometry Centre, says that light that enters the eye at a consistent brightness activates the photoreceptors at the back of the eye. However, when light flickers into the eye, it repeatedly activates those photoreceptors and can activate more of them. “Think of car brake lights,” she said. “The contrast holds our attention more than continuous play.”

bike lights

A 2018 emergency lighting study conducted by the Cumberland Valley Volunteer Firefighters Association in Pennsylvania also concluded that a slower flash rate attracts more attention than a slower flash rate. But there’s a limitation: a study by the Colour Use Research Laboratory on how the brain processes flashing light showed that our eyes respond best to light that flashes at 4 to 8 hertz (cycles per second).

Optimal settings

When riding at night, you should always have at least two lights on your bike or ebike: a front light to illuminate the road ahead and a rear light to allow drivers behind you to 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 headlights range from 250 to 2,000 lumens (compared to 700 to 1,200 lumens for car headlights). Alex Applegate, marketing manager for bike manufacturer Bontrager, says, “For a light designed to be seen, many riders are comfortable mountain biking at about 700 lumens, but the lowest I’d really start recommending is 1,000 lumens.” Clothing and accessories, such as lights. “If you commute on the open road and use lights to see, I would use the same recommendations. In urban environments with more ambient light, you can use fewer lights.”

Your tail light should be red and preferably pulsating, and it only needs to be bright enough for other vehicles to see you. Your rear lights only need to be 50 to 100 lumens- much less intense than your headlights. Remember: it doesn’t need to help you see, just be seen.

It’s not just about lumens, either. “Lumens are a measure of total light output,” Applegate says. “The higher the number, the more total light is put out. But it’s not as easy as more lumens equals more visibility – optics and focus play a big role in where the light goes and how far you can see it or be seen when you use it. Think of an ordinary light bulb: it’s very bright up close, but less visible from a distance. To be visible at a meaningful distance, especially during the day, the focus and optics of the light are just as important as the lumens.”

Not all models offer a pulsing option, so be sure to do your research before purchasing.The Bontrager Flare RT, TraceR MK1 Daybright, and all lights and sports lights include a pulsing option. According to this study by Trek/Bontrager, which sells daytime running lights, if your lights don’t have a pulsing option, flashing or strobe lights are better than solid beams, especially at night.


Daytime running lights aren’t required by law, but a Trek/Bontrager-sponsored study found that cyclists with continuous permanent running lights had a 19 per cent lower accident rate than those without. Getting a driver’s attention when the sun is shining requires a more powerful light source or flashing pattern. daytime running lights such as the Bontrager Flare RT have a different, more focused beam pattern that provides greater visibility in bright light. However, if you don’t have dedicated daytime lights, switch both the front and rear lights to the brightest setting available and switch them to pulse or blink mode. According to the same study compiled by Trek, “[daytime] use of a blinking taillight can make you 2.4 times more visible than a rider who doesn’t use a taillight (and 1.4 times more visible than a rider who uses a taillight lit in steady mode). Some lights, such as Light and Motion’s Vya Pro or Garmin’s Varia Smart Light, automatically detect changes in ambient light and adjust the intensity and flash frequency accordingly.

Light Positioning
No matter what mode your light is in, if it’s not positioned where drivers can see it, it’s useless. While it’s certainly nice to have a light mounted on a visible body part, such as the head (via a helmet), Cascade Bicycle Club’s Ryan says you should only do this for a headlight if you also have a light mounted on the handlebars. “If your only forward-facing light is located on your helmet, then you can always see where you’re looking,” he says. “But if you turn your head, vehicles travelling in the opposite direction of travel to you will no longer see your lights (or potentially you).” If you’re attaching a taillight to your seatpost or rear upper forks, make sure it’s not blocked by side cases or tyres. As with any new piece of kit, familiarise yourself with your lights before hitting the road.


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