Rules of the Road

With daylight getting shorter, it’s time to shed some light on bicycle lighting

Bicyclists required by law to have a front light and back reflector when they ride at night, but making sure headlamps aren’t too bright is crucial.
Bicyclists required by law to have a front light and back reflector when they ride at night, but making sure headlamps aren’t too bright is crucial. The Bellingham Herald file

Question: What kind of lighting is required to ride my bike at night? Are strobe lights legal?

Answer: At the minimum, the law requires a white headlight on the front of the bike, visible from at least 500 feet, and a red reflector on the back, visible from at least 600 feet.

But this is America, and if a little is good, then more is better, right? Not always. There seems to be an arms race for the brightest headlights on both cars and bicycles, and the bikes might be winning.

It used to be that the message to night-riding cyclists was, “Put a light on your bike.” I still see people riding without lights at night, so that message still needs to get out there.

However, there’s a new message made possible by advances in LED and battery technology: “Hey, can you turn it down? You’re blinding me.”

If you were so inclined, and had a budget of more than $500, you could buy a 3,600 lumen light for your bicycle. To put that in perspective, federal law limits high beam headlights on cars to 1,200 lumens each, so your bike light could be 50 percent brighter than your car’s headlights. (Assuming your car headlights are legal. Brighter-than-legal lights are available for off-road use, but that limitation doesn’t stop rule-ignoring drivers from putting them in their street-driven vehicles.)

Some of the bike light manufacturers describe their products as “the sun at your fingertips” and “blindingly powerful.” I don’t think any cyclist would actually want to encounter a blind driver.

While these super-bright lights are intended for trail riding, the law doesn’t prohibit them on the road. Yep, there are limits on car headlight brightness, but not on bike lights. I’m guessing that we have no limits on the brightness of bicycle lights because until recently, the problem with bike lights was not that they were too bright, but that they were too dim. It’s a situation of the law not keeping up with technology.

I’m a bit off track from the original question now, but if you’re shopping for a light for your bike, the best one isn’t the brightest one; it’s the one that lets you see without blinding everyone else.

Nearly any bike light on the market right now has the ability to blink or strobe. And a lot of cyclists are sure that a blinking light is safer than a continuous light.

First we’ll consider the law, and then we’ll look at safety.

In the section of the Revised Code of Washington (RCW) referenced earlier, it doesn’t mention anything about blinking headlights, but it does state that in addition to a red rear reflector, cyclists can use either a continuous or blinking red light on the back of the bike.

If we dig deeper though, the law has more to say about headlights, and the riders who like blinking lights aren’t going to be happy about it. In the section on vehicle lighting, the RCW states that flashing lights are prohibited (with a few exceptions that don’t include bike headlights but do include taillights.)

The Washington Administrative Code is even more specific, listing flashing white lights as prohibited on any vehicle except emergency vehicles, school buses and tow trucks. A bicycle is included in Washington’s legal definition of “vehicle.”

From a safety perspective, a couple of studies have looked into the effectiveness of blinking lights compared to continuous lights.

A Dutch study reviewed various types of bike lights and found that drivers notice blinking lights sooner, but have a harder time judging the speed and distance of a blinking light than a continuous light. A study from New York evaluating lighting on snow plows found similar results. You’ll also learn from the study that a lot of people crash into snow plows.

Think about the kind of information you’re giving other road users with your light. If a steady light communicates your location and speed better than a flashing light, I’d say the advantage goes to the steady light.

The law requires that bikes are illuminated from a half hour after sunset until a half hour before sunrise, but I’ve talked with cyclists who ride with lights on day and night, and they’re convinced that it helps drivers notice them more in the daytime, too. They’re probably right; a Danish study found that using lights during the day reduced crashes by over 30 percent.

Our daylight is getting shorter each day, so if you’re on a bike, make sure you’re equipped with good lighting, and if you’re in a car watch out for your fellow road users on two wheels.

Road Rules is a regular column on road laws, safe driving habits and general police practices. Doug Dahl is the Target Zero Manager for the Whatcom County Traffic Safety Task Force. Target Zero is Washington’s vision to reduce traffic fatalities and serious injuries to zero by 2030. For more traffic safety information visit Ask a question.