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‘Retina-shocking’ flashing bike lights cause more problems than they prevent, article argues

With the days getting steadily darker, it's not just visibility that's a concern for some cyclists. To many, the best means of seeing and staying seen -- namely, lights -- can be a problem, too.

Image credit: Ed Dunens.
Image credit: Ed Dunens.

With the days getting steadily darker, it’s not just visibility that’s a concern for some cyclists. To many, the best means of seeing and staying seen — namely, lights — can be a problem, too. Specifically, though, it’s those high-powered, ultra-luminous lights that tend to be the issue.

According to an article published by NextCity.org, the offending lights are those that are “bright as the sun,” and flash to boot.

To read author Josh Cohen’s take on it, the effect is similar to something occasionally experienced by motorists: you’re driving along, eventually come to a stop sign, and another vehicle with its high beams activated pulls up behind you. You find yourself squinting; momentarily, your vision is disrupted. That, it goes without saying, can be a big, big problem when you’re riding a bike.

“During rush hour in bike-heavy Seattle where I live,” Cohen explains, adding that flashing front lights are illegal in Washington state for this reason, “it is impossible to ride more than a few minutes at a stretch without getting blasted from another retina-shocking dose of flashing light from another biker heading in the opposite direction.”

“I’m sure it’s the same in your city,” he added — something that cyclists in, say, Vancouver might understand.

High-intensity, high-lumen lights are becoming more accessible to cyclists, having dropped in price significantly in recent years. A light in the 1,200 to 1,600 lumen range, for example — something Cohen describes as “enough to turn night into day in the path of your headlight” — costs in the neighbourhood of $100, meaning there are a lot more of these lights on the streets. A predictable response to this might be that there are plenty of car headlights that are just as powerful, if not more so. So what’s the problem?

The answer is simple, Cohen argues: design.

Image: Digital Nuisance via Compfight cc
Image: Digital Nuisance via Compfight cc

“Though many bike commuters are now riding with headlights on par with a car’s headlights, there is a critical difference,” he says. “Car headlight beams are focused and directed down the road to ensure they don’t blind other drivers. Typically attached to handlebars and helmets, bike headlights point out and up and have a tendency to shine into the eyes of passersby. Add in flashing and it’s a recipe for irritation at best and danger at worst.” Though there’s plenty of solid, clear evidence that flashing lights can help a rider remain seen — Cohen cites a 2001 study published by Rensselaer Polytechnic Institute — they can also potentially complicate matters. Referring to the same study, the author notes that flashing lights can make it harder for other road users, like drivers, to properly appraise a rider’s speed and proximity.

His argument, of course, isn’t entirely in opposition to flashing bike lights. Grey, overcast days or rainstorms are conditions that find them beneficial, he says. Overall, it’s “intuitive” to use flashing lights under the assumption that they make a rider more visible. His closing argument, however, suggests that this assumption is baseless.

“Using flashing bike lights at night doesn’t make you safer, can create medical problems for people, can be dangerous for other bicyclists and is definitely obnoxious to be around. So really, why on earth would you do it?”

What do you think?