I use this headlamp which I consider fairly bright at 280 lumens. A single low beam on a car is 600-700 lumens. I never feel like my headlamp is coming close to annoying a driver. They drive against double 600 lumens oncoming cars all the time. My head lamp is also tilted down towards the ground shining a spot anywhere from 3 feet to 20 feet in front of me.

I do have occasional drivers flick on their high beams temporarily. I always assume they just want to identify what is causing the light on the shoulder of the road. Occasionally they leave their high beam on which I find annoying. I usually look off to the side and on the ground to not be blinded.

I do a lot of running at dark.

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"If it costs you 30 minutes at Maryland so what" -dwreal

Honestly, unless your headlamp is 400+ lumens, I wouldn't worry about it at all.

Note that sometimes cars seem like they're flashing lights because they go over a bump so the angle of their headlamps gets temporarily brighter, but they're not even flashing you.

If they are flashing you, take comfort that your light is definitely keeping you safe, and you ARE being noticed. It should be very easy, however, to also turn your headlamp power down 1 notch if it's a super-bright one, or even if it's not, angle it steeply downwards for that stretch of road.

I have a 500+ lumen headlamp that is definitely super-annoying if you're seeing it head-on, and I do turn that one down whenever I'm on roads with car traffic and it's not 2AM in the morning. However, lately I've found it's just easier and more convenient to use my 350 lumen Fenix headlamp which isn't totally blinding to cars as long as I'm not beaming the drivers with it.

Make sure you aren't inadvertently looking at the cars when running. I usually point my lamp towards the ground more so more of the ground is lit up but that they can still see me.

I run and bike a lot at night and get this sometimes, as well.
I figure that lets me know that they actually saw me - and that's a good thing.
If the light bothers them; F 'em! At least I'm not getting killed by them.

I get that, too, and honestly, I think they truly believe that they're helping you to see the road better than the little "Miner '49er Light"

But, yeah, at least they can see you

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"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin

I would just assume that they are fellow runners giving me a nighttime thumbs up by flashing their headlights. If they were pissed, they would honk.

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It is not how many lumens. It is where they are pointed. I run almost exclusively in the dark. I use a 75 lumen head lamp pointed at the ground ahead of me. It does an excellent job giving me the light where I need it. And, it is pretty intense if it hits someone directly in the eyes. If you have anything in the low hundreds of lumens, and you flash a driver directly in his eyes, you are putting him and yourself at risk. At that moment, he is unable to see you or the road.

if they flash at me im happy they see me....... mine has an angle down adjustment on it but I do not mind it being very visible to drivers.

Remember the rule about cycling, wherever your eyes go, is where your bike will go. Same goes with driving. I want the car to notice me, but not look at me for any period of time. If they are flashing at you, they are likely looking at you waiting for a response of some sort. Which means they are spending too much time fixated on you. Just saying.
Mark

This is correct. I do a lot of running at night on a paved trail and have done so for at least a decade. I do so without a headlamp because you'd have to be pretty blind to not see the path. There are a few people who have started using headlamps in the last few months and have them pointed directly forward which helps nobody but themselves - it's literally blinding to cross paths with these guys. I've not said anything to them, but likely will the next time. Pointing it at the ground is one thing, but blinding other people is quite another.

Incidentally, to dramatically improve your own night vision while running -- whether you are using a headlamp or not, try to run with a cap that has a brim - like a baseball cap or a visor. Keep it low enough that it blocks the oncoming lights but you can see the ground in front of you. Makes a huge difference.

This is correct. Been doing it for years.

I'm running on the road, right on the white line, but between me and the edge of the pavement, many obstacles could be lurking in the dark: potholes, leaf piles, random twigs & branches, rocks and sand and gravel and shoes and needles and underwear and hubcaps and all sorts of other shit

Some years ago - never mind how long precisely - I was running around in the rain, back in the more sparely populated part of town, where the only light was the ambient glow of Xmas lights. I thought I knew my way around back there pretty well, even in the dark. A car was approaching, so I drifted myself a little closer to the edge of the road. There are no curbs or sidewalks out that way; the street gives way to an uneven boundary of gravel before the folk's lawns start. It was a rainy night, as I said, so I had to hop over a sandbar that had shoaled up in the stream along the shoulder. I kinda shorted it and stepped about a foot from the end of the "island." There was a surprising CRACK! and I skidded a little bit [didn't fall, though]

It was a deer carcass ... I'd landed on her rear leg

That was the moment when I decided: "I really, REALLY gotta get a headlamp"

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"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin

Totally agree with the sentiment that cars should be FINE with even 350lumen lights so long as you're not beaming them directly into the driver's eyes. Oncoming car traffic is wayyy brighter than a runner's puny single headlamp aimed at the ground.

Now if you have a 500+ lumen headlamp, THEN you probably should consider turning the lumens down against oncoming traffic - that's like a high beam. (I have one, so I know.)

Be extra courteous to approaching RUNNERS who will get blinded by even low-lumen lights if they're not using a headlamp themselves. It's usually pretty easy to click down to a lower level of light until you pass them, or if that's a problem, it's super easy to just use your hand to block the spilling headlamp light in their direction.

You can have a million lumens, as long as they are aimed at the ground. But, the problem is lux, not lumens. And the problem here is that runners are likely looking up at cars and blinding them. In that scenario, lumens are irrelevent. You are putting a narrow beam directly into the eyes of a driver, which can be a lot of lux, because it is less dispersed.

Comparing a car headlight lumens to a runner headlamp is apples and oranges. Car headlights produce a lot of lumens, but the beam patterns are designed to throw light at least 50m down the road and about 6m across the road. That is a huge area and dilutes the lux. Further, most of that pattern is cut off and below eye-level of oncoming traffic. So, the lux hitting the eyes of a runner or another driver is managed. However, when you point your headlamp, with its narrower beam pattern, directly into the eyes of a driver, the lux is much higher than lux from oncoming traffic. (You got it right with the last statement... but why would an oncoming runner get blinded when a car would not? They are the same.)

God Bless Lux Interior

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"What's your claim?" - Ben Gravy
"Your best work is the work you're excited about" - Rick Rubin

I agree that directing the light is a key feature.

Alas, I haven't found a runner headlamp that will cutoff the beam so it won't be blinding (unlike car lights.)

As well, runners typically do NOT look at cars as you suggest. The ONLY time I ever do that is when I intentionally do so when a car is clearly going to hit me and doesn't see me (cars pulling out of driveways into my path is the most common scenario - you can see the super jerk stop they do when they realize I'm there.) Unfortunately, the lack of beamforming of runner headlamps means that the spillage itself can be pretty blinding, even if the beam is mainly aimed at the sidewalk.

I say my 500+ lumen headlamp is like a car headlamp on hi beam due to subjective comparison. Not scientifically correct, but if you stand facing my car where a runner would be facing oncoming traffic, the headlamp's brightness is very similar to the car beam on high (the car lux is likely higher as you state but has beam cutoff to reduce the spillage.)

I was thinking about the same thing....you want them to be aware of you but not "pointed at you". So how do we get that working. On a plus note for the bike, if you look/lean your head right the entire bike veers right. Just try this on your rollers and you'll see that just moving your head a tiny 1 cm to the right will make your back wheel move to the right. Same with running....lean your head on the treadmill one way or the other and your body goes there. For the car it is a bit different....you can lean your head all you want and although your body will lean with the head, the steering fortunately does not move with the head....but instinctively as drivers we do kind turn the steering column in the direction we are looking, its just that its not governed by the law of physics like in cycling or running where the direction of the movinng object (bike or body) is actually affected by head displacement from the center line!

We have had this discussion about bright clothing is daylight riding too and whether it gets drivers too fixated on you such that they drive into you. I am thinking that there have to be actual studies by highway construction authorities on which the bright clothing of construction guys is based. If bright clothing or bright lights really gets us to drive into the bright objects, you'd hope by now, all the construction work guys would be totally in stealth apparrel.

One more thing....when I train in the dark in any sport, even though I have bright and reflective gear, I use the assumption that drivers cannot see me and they plan to slam into me thinking where I am is open tarmac. I've never had an incident working out at night with traffic, probably because I am more self aware and probably because drivers are more surprised to see me than in bright daylight.

Dev