The main reason seems to be that it's hard for others to to gauge your speed when your lights are flashing.
Apparently, the absolute safest solution is to have two rear lights side-by-side -- one that is always on and one that is always flashing.
It doesn't seem like there's clear data on which is safer if you have to pick only one. Different countries/states have chosen differently.
I once worked on a device where we were required to blink the Important Safety Light™ on-off. I often glanced at this light out of the corner of my eye, and saw that it was off, so we were Safe™. We were not Safe™: it was just in the off phase of its blink.
I am very glad I never got hurt by trusting that light.
I wanted to blink it bright-dim but was denied by people who said that IEC 61010 required it to blink, and blinking bright-dim isn't blinking. I didn't quite understand that objection.
Ideally (for me) you could have smooth high-low alternation or colour alternation.
(I recognize that something that looks like emergency services, e.g. alternating blue/white may be illegal, and that colour-blindness may limit this approach.)
If a safety indicator needs to be visible at a glance, why did it blink at all?
Blinking only works for things that are in your vision and need to be the primary focus.
It seems like blinking to begin with is terrible design for something like this, or else having it be in the corner of your eye is the terrible design decision.
Beats me! But they've apparently flashed for ages and ages on these things, and somewhere along the line it got standardized.
> It seems like blinking to begin with is terrible design for something like this, or else having it be in the corner of your eye is the terrible design decision.
This is benchtop equipment, not cars, so "corner of your eye" has a little bit different context here. But, yes, I kind of agree.
It is also really important to get this one right since for this particular type of device, conditions are lethal (yes, genuinely lethal, no exaggeration) if you get cavalier with it.
Also flashing is really fucking annoying, and I my own experience is that it does notale cyclista more visible or safe. I don't use flashing lights myself, even though I can't see the rear one and eould probably rather be annoying than dead.
To be clear, I'm talking about rear lights only. The front light is white and always-on so you can see the ground. Plus you can see what's in front of you, so you avoid things, people don't need to avoid you as much.
It's the rear red light that flashes. You yourself don't see the flashing, but it increases visibility so people don't run into you, when you can't see them behind you.
When I'm behind a cyclist with a flashing red rear light, it doesn't bother me. It feels safe. It probably encourages me to keep a little extra distance from them, which is a good thing.
If bikes didn't move, a blinking light would be fine. But they do move and it makes it really hard to tell where the bike is in the dark.
If you are riding a bike and you're lighting up the heads of oncoming riders or pedestrians you are being dangerous and obnoxious. Never shine a flashlight above someone's shoulders at night if you can help it.
Bicycle lights aren't blinding anybody. At least none I've ever seen. They're powered by little batteries usually.
The subject at hand was whether they flash or not. Not their brightness, which I've never heard anybody complain about.
They are much worse if they flash. That blinds and disorients. Even after they pass you won't be able to see anything for some time.
If you're somewhere without any other lighting and your eyes have adjusted to the darkness, then I can understand how they might seem bright. But I'm not really sure what you think the solution is. They're already vastly dimmer than cars, but make them any dimmer and the cyclist won't be able to see the ground and it won't be safe.
E-bike rentals don't have anything adjustable, and where I am, they're quite fixed at illuminating the ground.
Maybe there are people with e-bikes who can draw a lot more power and have higher-powered headlights? Are you talking about e-bikes specifically? But it's just not something I've ever seen. I'm certainly blinded by vehicles while cycling under certain circumstances, but I've never once in my life felt blinded by cyclists or even anywhere close. That's why I'm so confused by what you're describing. When you say "blow away your vision from half a mile away easily", I honestly can't even begin to imagine what you're talking about.
Stuff like this:
https://www.amazon.com/s?k=bike+headlight
You can even see people posting pictures of the light where it's clearly illuminating 10' up the tree on the side of the path.
I'll start paying more attention -- I'm curious now -- but I can still definitely say I've never felt blinded by a bicycle, or even close.
And the lights in that photo seem fine -- the road is pitch black just 20 feet in front. The tree is getting a lot of light reflected from the road and grass. The lights don't seem to be illuminating anywhere even close to as far as car headlights illuminate. None of that looks anything like what car headlights produce.
They absolutely are. They suffer from the same phenomenon as car headlights. They're often poorly aimed (at an upwards angle instead of downwards) and have adopted an insanely bright white colour. I frequently yell at other cyclists when they blind me.
People do it for safety, but it doesn’t help. I literally can’t see where you are if you have a bright light shining in my face. The same thing is true if I’m in a car. As long as you have lights I can see you. If your lights are obnoxiously bright and especially if they are blinking you have succeeded in making people want to harm you, not increased your safety. The drivers who aren’t paying attention will not be more likely to see you if you are just a blinding glow of light.