The US Military has developed weapons based on the concept that ultra bright lights can temporarily disable the target’s central nervous system incapacitating them. It appears that a number of bike light companies are using a similar approach to tail light technology.
Let me say categorically if your belief is the more light you are pumping out the back of your bike the safer you are – you’re wrong. Drivers drunk and/or distracted crash into police cruisers with their flashers going regularly enough that some researchers hypothesize that bright lights cause you to look at them and you steer where you are looking:
“The “moth-effect” is a myth in one sense and reality in another. The idea that drivers may steer off the road when they fixate flashing lights is likely correct, but they are not drawn to the lights like moths to a flame. Rather, they inadvertently steer rightward, which may or may not take them into collision with the roadside vehicle. Even normal, alert drivers in daylight conditions may steer in the direction of eye position during periods of intense fixation. The cause is likely error in judging heading under eccentric fixation when optic flow cues are minimal and when attentional focus prevents sensing of the need to correct the error. Although bright lights and fascination are not required, of course, it is impossible to rule out these factors in some accidents.”
~85% of car bike collisions are from cars turning or crossing the cyclist’s path while only 10% involve a car overtaking a bike and hitting it from the rear. So you should be far more worried about cars coming the other way than from the rear.
I’m not suggesting you don’t use a rear light or that it should be feeble. What I am saying is buying the brightest light possible and shinning it into the eyes of drivers and cyclists approaching from the rear is not smart and is not going to increase your safety. It may even decrease your safety as you are impairing their vision and ability to operate their vehicle most profoundly as they are about to pass you – a time when you want people in cars to be at 100% performance.
How do you know if you are doing something wrong? Swap bikes with a friend and ride behind him at varying distances on a dark MUP or dark street. Note how you felt as you were exposed to the light from the back of your bike. Try the same thing, but this time in a car on a dark road and then a busier road with more lights. Again note how visible your bike was and how the lights you are using felt from that perspective.
How to be safe without burning out other folk’s retinas:
- ride predictably…cars expect cyclists to be in certain places on the road and to behave in certain ways. That’s where a driver is looking for you. The more predictable you are the easier it is for you to be spotted and avoided.
- ride intelligently…every route is different and has different pros and cons. Your most efficient safe commute in normal conditions may be dangerous when it’s foggy due to the many business lights/signs that could mask your bike’s lights. It might be better to take a longer slower route on side streets that day and accept the delay it will cause.
- signal effectively…a black glove on a black jacket may not be an effective way to signal the fact you want to turn left. Be aware of what you are wearing and what you look like to other road users. When in doubt wait until the road is clear before turning or changing lanes.
- use a rearview mirror…if getting hit from behind concerns you than keep an eye on what’s to the rear. If you see a car swerving like the operator is drunk just get off the road entirely until they are gone.
- wear reflective material…it’s effective and cheap. Ankle bands and wrist bands are awesome for low cost visibility and turn signalling. A reflective vest is an easy way to amp up your visibility to cars without needing batteries or causing vision issues.
- use two lower power lights vs. one ultra powerful light…LEDs have a small window of very bright light output. As you move sideways or up/down away from this zone the light power fades. Two light allows you to aim at different spots [20′ away and 100′ away or aimed slightly left and right] giving you more chance to be seen but not putting excessive light into any one area behind you. Two lights also mean a light failure or low battery doesn’t turn you into a totally black Road Ninja.
- Set your lights to solid mode so they aren’t as dazzling.
- Be considerate. If you do use a powerful rear light on rapid flash mode be ready and willing to change modes while riding if you see another cyclist or driver following you in a situation you know they’ve already spotted you.
Just like wearing a helmet doesn’t mean you’ll be safe on your bike – using the most powerful light you can get your hands on and assuming it will mean you are safe on the roads at night is a mistake. By all means use a bright tail light [and wear a helmet], but make it part of a bigger plan for night time safety not your only line of defense. And when you are holding that Dinotte tail light in your hands thinking how safe you’ll be when you turn it on and aim it into the eyes of over taking drivers consider for a moment that it’s a weapon and try approaching your bike from the rear on a dark street/MUP. If you can’t see anything, but a huge red spot for 20-30seconds afterwards maybe consider that your light may actually impair your safety or someone else’s as that dazzled driver passes you at 55mph.
PS – if you have any older LED tail lights like this Blinky 7 from Planet Bike consider putting them back into service. Instead of one uber bright LED that focuses all it’s light in one intense spot they use a bunch of bright, but lower power LEDs that push out light over a wider area. When you consider a wider viewing angler they may even be more visible than their brighter siblings. I’ll be using one of these on my rando rig along with a bunch of reflective material. It will be more than bright enough [on solid mode] to be seen on the rural roads/highways typical of Canadian brevet routes, but not as deadly on the eyes of randonneurs that may be following me for several hours.