Flashing lights and bikes have become like love and marriage – they are strongly associated together, but there CAN be problems. When should you flash your bike lights, and when is it not a good idea? Here’s a guide to when to use your bike lights on flashing mode.
Most good quality bike lights have a range of modes, including steady and flashing. On any given night where there are a lot of cyclists out, you will see both white (front) and red (rear) bike lights flashing all over the place. This video taken on the Burrard Street Bridge in Vancouver shows a whole stream of cyclists – and every one either has flashing lights, or no lights at all. Flashing lights seem to be the most popular choice – but not every one loves them. In fact, there are times when they should not be used, or should be used only with care not to disorient others.
For the longest time I thought that as long as there was sufficient ambient light for me to see the ground, I should always use a flashing light rather than a solid light, because it grabs attention, and it saves on battery power. At that time, I would only switched to steady light mode when I was trying to see the road and watch out for potholes. Well, I have learned over the years that there is more to it than that.
Flashing bike lights are attention grabbing but …
So, here is the key problem with flashing bike lights – when people see a flashing light at night, it is hard for them to judge how far away it is, and how fast it is moving. This means that a motorist may misjudge where you are, and that is NOT good.
We have actually had the worst-case scenario of this, where a man driving an F-150 on a broad, empty road drove CLOSER to my wife (Maggie, Mrs. Average Joe Cyclist) because he was curious about what her flashing bike lights were! He got so close that his side mirror clipped her shoulder. Luckily, it was a newer truck, so the mirror gave way. That, combined with Maggie’s forward momentum at the time, saved her from serious injury. She was also able to stay upright, rather than falling under his wheels. Still, she did need several months of physiotherapy to get her shoulder right. Luckily, she just got right back on her bike, and was not scared off.
Fortunately, most road users are not that stupid. Still, we do need to make it as easy as possible for other road users to know where and what we are, and how fast we are moving. Not just motorists, but pedestrians and cyclists as well. As a cyclist, I appreciate when I can see other cyclists coming towards me.
To that end, these are the recommended best practices for how to use flashing bike lights.
How to use your front bike lights while cycling at night
You should not cycle with only a very bright, flashing front bike light. This will make it hard for oncoming road users to judge where you are and how fast you are coming at them. If your flashing bike light is 300 lumens or brighter, it may even seriously disorient people. In fact, since I wrote this post, I have had interesting feedback from many cyclists about the problems of flashing lights: It seems that they were invented when bike lights were much dimmer than they are now. But now we have ultra bright LED lights, sometimes as bright as 3,000 lumens. Many cyclists experience disorientation, headaches, migraines, and nausea when 3,000 lumens of flashing LEDS are coming straight at them.
So for the sake of your fellow cyclists, please be very careful about how you use flashing lights, especially if your lights are very powerful.
The best bet is this: try to avoid using a flashing front light at night. A steady light is clearly visible at night, and does not hurt and disorient other people (unless it is excessively bright and aimed at their faces). If you must have a flashing light, use one not-very-bright flashing bike light (not more than 300 lumnens) PLUS one steady bike light. The steady light helps you to see where you are going, and also makes it much easier for oncoming road users to judge how far you from them, and how fast you are approaching them.
Try not to blind other road users!
As always with lights on any kind of vehicle, make sure that your bike lights are not angled in such a way that they blind oncoming road users. This is unsafe for them and for you, and can cause collisions or road rage. Bear in mind that a single car low-beam headlight is about 700 lumens. With so many bike lights now offering 700 lumens and more, it is very easy for cyclists’ lights to blind other road users.
My personal favorite is my LuminTrail (reviewed here), which I wear mounted on a helmet. The mount has a lot of flexibility, so I can angle the light just right for the conditions. Also, because it is on my head, I can quickly turn my head away from someone if need be. Whenever it is on its full 1000 lumens power, I angle it straight down at the road.
How to use your front bike lights while cycling in the daytime
First of all, yes, I definitely advise using bike lights in the daytime. It seems that this is uncommon, which I find odd. I once spoke with a bus driver who told me that he loves cyclists with day-time lights because he can see them from a block away, whereas without them, he found it hard to spot cyclists until he was uncomfortably close to them. That sold me! Anything that makes me more visible to people driving giant vehicles that could kill me is good with me.
However, no matter how bright your bike light is, it is going to be hard for other road users to notice it in the daylight while it is on steady beam. Therefore, daytime is definitely the time to flash those bike lights! All the same, do check that they are not so intense that they manage to cause disorientation and pain to others, even during the daytime.
In the daytime you don’t have the problem of other road users’ not being able to see how far away you are and how fast you are going, because you are visible.
The other benefit is that your bike lights will last longer in flashing mode than on steady.
How to use your rear bike lights
The same principles in general apply to rear lights, expect that these lights are usually less bright, and are much less likely to cause discomfort and disorientation to other road users. In general, your best bet for maximum visibility is to have two rear bike lights (one steady and one flashing) at night, and at least one flashing rear light in the daytime. If you don’t have a rear light, start with a highly rated one, such as the Cygolite Hotshot.
Side Bike Lights
I also highly recommend side bike lights so that you can be seen by road users approaching from the side. Monkeylectric lights (reviewed here) are high quality, long lasting, bright and fun. They attach to your bicycle spokes, and can be programmed with various flashing combinations and patterns – such as flashing green and red stars at Christmas time! Of course, these lights flash all the time. However, they cannot blind or disorientate other road users, as they consist of tiny LED lights, and of course they are not facing forward towards oncoming road users.
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