Taking a different tack, what's clearly illegal for motorists?

It's illegal for a motorist to use high-beam headlights closer than 500 feet away from oncoming traffic, because high beams closer than that create hazardous glare that can blind oncoming drivers. ("blind" being used in the legal sense of interfering with the vision of oncoming drivers.)

So, if it's illegally dangerous to shine a 1,500-lumen high beam in drivers' eyes at 500 feet, how far away is it safe to repeatedly flash a 1,000-lumen bicycle headlamp in their eyes?


It's illegal for a motorist to use high-beam headlights closer than 300 feet behind a vehicle moving the same direction, because the glare can be dangerous.

If it's illegally dangerous to shine a 1,500 lumen high beam in a driver's rear view mirror at 300 feet, how far away is it safe to repeatedly flash a 1,000-lumen light in their rear view mirror?

+1

Go look at the lights your fellow cyclists are using. I have yet to see anyone that has their lights aimed even the 20 meters (60+ feet) down the road in the diagram you attached. My lights are aimed from 20 to 30 feet in front of my bike and they are typical of just about all the other cyclists I see on the road. Even the blinky riders (I'm not one of them) don't have their lights aimed high in my experience.

If you look at the diagram that you attached more closely, the beam for the driver's side spreads a long way into the on-coming driver's lane and a lot further out than any cyclists light would. The whole point of the asymmetrical lamp in the diagram is to provide the driver "with long seeing range on the right and short cutoff on the left so oncoming drivers are not blinded." Since we cyclists are much closer to the right side lamp or even further right than that lamp, how is it that we 'blind' on-coming traffic but the car doesn't? Especially considering that the right hand lamp of the car is throwing a beam out 60 m (around 250 feet).

Contrary to popular belief, I'm not a jerk. If I thought my lights...or those of other cyclists...were hazardous or dangerous to motorists, I'd change things so as to not cause problems. However, as cehowardGS has pointed out, there is a balance between being 'neighborly' and being safe. In an urban environment, my lights have to compete with a lot of light sources. There are, literally, 10 of thousands of light sources in the 10 miles of my commute. If I were to cut back on the intensity of my lights in an attempt to negate my impact on motorists, the lights would be lost against that background of the tsunami of light we humans feel we need at night. Being nice to motorists by becoming invisible isn't a strategy preserving my third dimension. I like my third dimension.

I've been following both sides here and I can see the valid points, drivers can't actually be blinded by bright bike lights and they aren't really comparable to auto headlights. At least current lamps aren't. I know you're also focusing primarily on cycle-auto interactions where the bicycle is far left of oncoming traffic.

However, I'm a little shocked at the suggestions of flashing drivers with high powered helmet lights while stopped at intersections. From the time I first began driving, aiming directly at a motorist's face simply wasn't done and that was long before high-powered LED lights were available. It was disruptive, possibly dangerously distracting and a theoretical traffic ticket. I still think we can go too far with using these lights to be visible.

The other counterpoint to all this is when bicycles pass towards each other on narrower lanes. Especially in a bike lane or path, within 5 or 6 feet, I can be literally blinded for a few seconds by a 1000 lumen light on somebody's helmet or even handlebars, aimed directly at my face. You know rationally that it's not deliberate but it feels extremely aggressive for the other guy to selfishly endanger you. So I think a lot of care needs to be taken with these lights, and it is an issue that is so far unresolved.

Not thick at all - actually a very good question.

The short answer is because it is the current flow through the LED, not the voltage across it, that causes it to emit electrons. Also because the voltage is, for all practical purposes, a fixed value for any given LED, regardless of current or brightness, while both current and brightness can change, and are directly proportional to each other.

Longer answer:

Current flows in an LED in the form of electrons and electron holes. When the two meet at the PN junction, they recombine, emitting a photon in the process. The more charge carriers flowing through the device, the more recombinations there are, and the more photons are emitted. The flow of charge carriers is current (that's the definition of current).

So why does changing the voltage when using a voltage source cause the brightness to change? It is a characteristic of an LED that for any given current draw, it will exhibit a certain voltage drop (or vice versa). Look up the I-V curve of an LED, and you'll get a handy graph that relates current and voltage. If you measure either value, you can find where it intercepts the curve, then look at where that point lies on the other axis, and you'll get the other value. In theory, you could feed an LED with a voltage source by figuring out what voltage you need to cause the LED to draw the desired current - but it is the current flow, not the voltage, that controls the brightness (remember those electrons and holes recombining and emitting photons).

The I-V curve will be different for different LEDs. Even for two supposedly identical LEDs - same manufacturer, same part number, same batch - there will be variations. It will also change with temperature. Since the current changes a lot for small voltage changes, being off by even a bit on the voltage can be a big problem - and voltage for the desired current can vary by quite a bit, even with identical LEDs (often around +/-20% or so).

Take a handful of identical LEDs, hook them up so you can measure the voltage across and the current through each one. Now feed them all with the same fixed voltage. You'll see that they are all operating at different brightness, and have different current draws - and the brightness will be proportional to the current. Change the temperature, and you'll see both the current and the brightness change - but brightness will still be proportional to current.

Now feed those same LEDs with the same fixed current. You'll see that they are all operating at different voltages, but all have the same brightness. Change the temperature, and you will see the voltages change, but they'll still be operating at the same brightness.

Clearly it is the current, and not the voltage, that is controlling the brightness. Changing the voltage of a voltage source is simply a means of changing the current, though as you can see, you can't properly control the LED because you have no way of knowing the exact relationship for any one LED (or even at any one time for the same LED) and therefore no way of knowing what the exact current will be. This means some LEDs will be too dim, while some are being overdriven (resulting in drastically reduced life span, or even almost instant destruction). Feed it with the desired current, and it doesn't matter what the exact voltage is.

BTW, there's another problem with the I-V characteristics changing with temperature if using a voltage source. Current through the LED will cause it to heat up, and as it does it'll draw more current for the same voltage. The increased current will cause it to heat up more, and it'll draw even more current. This is known as thermal runaway, and can lead to failure of the LED as it becomes increasingly overdriven - even though the voltage hasn't changed at all (but the current - and brightness - sure have!).

On my daily commute, I routinely encounter riders whose lights light up my head and shoulders, meaning they're aimed up from bar height, not down. I routinely see lights aimed left of center, to be "more visible" to motorists. And I routinely see bright, flashing, helmet-mounted lights that sway around all over the place, into traffic, into the eyes of fellow cyclists, down cross roads, etc.

As an elected official, I hear complaints from constituents about glare from poorly-aimed, overly-bright bicycle headlights on local streets and trails.

This is a real issue, it's not something I'm making up, and it's something that's going to attract legislative attention if cyclists don't do a better job of self-regulation.

Despite what others here claim, you are not alone. I too constantly encounter poorly aimed lights.

There appear to be several types of offender, the main ones being

• The ones out to deliberately annoy
• The ones who are trying not to annoy, but their lights have slipped and they haven't noticed
• And the ones who think that they only need to have a light on their bike, but don't give a moments thought to how they are aimed or if anything is obstructing them.

Of those, the first is rare but do exist whilst the majority fall in the other categories.

Motorists in the UK have to have their vehicles checked annually, and if their headlights are mis-aligned they will fail the test and be removed from the road until they can pass the test. Cyclists are not required to have any such tests, also the nature of cycle lights are such that because most are removed they are much easier to mis-align accidentally.

One last point is that most car headlights and the older halogen/xenon bike lights were in the yellower warm-white spectrum, whereas the LED bike lights fall in the bluer cool-white spectrum, the latter being harsher on the eyes for the same light output, one of the reasons yellow fog lights existed for so long.

In this thread, all views/opinions are respected.

With that said, I like to ask this question. What percentage of us bicyclists are running these high powered lights?? The strongest light I am running to date it PB 2W Blaze up front, and a Superflash Turbo in the rear. Lately I been running a pair of $2.00 lights up front. Yup, $2.00 each..;)

Off the top of my head, I will say, the percentage is way down. I would say about 10% of bicyclists are running high powered lights. In addition, bicyclist that have high powered lights, are most likely experienced and know how to handle the high powered lights.

In my neck of the woods not even that much. At night I can only judge by the brightness though so they may be 500 lumen or less for all I know. Mine is nominally 500, and some of the lights are at least as bright.

The helmet light invariably swings toward me though. It's only natural human nature, which is why I suspect it may not be a great idea. As the lights get brighter and more available to newer riders I can see a problem in the making. If cyclists in general don't get out ahead of it - and I kind of doubt that we will - I fear we'll be looking at enforced regulations down the road.

You need to recalculate your speed in feet/sec. 30 mph equals 44 ft/sec. 0.7 seconds at 44 ft/sec equals 30.8 feet of travel.

I wear a helmet light because of the utility of the light. I have used it to flash across the face of motorists but I don't do it expect as a last resort. The few times I use it per year is when a motorist isn't paying attention and pulls out across my path from a stop light. The point it to get them to stop and not squish me.

I agree, just recently I had a motorist who was traveling in the opposite direction to me not only "flash" his highbeams at me, but leave them on thus "blinding" or "dazzling" me. As I passed I'd said (I'd thought not loud enough for him to have heard me "dim your highbeams." He'd continued down the road and did a U-turn to come back and explain why he did what he'd done. It seems that he felt "justified" in doing what he did in response to my lights being "so bright."

I tried to point out to him (I don't know how successful I was) that drivers actually have more control over their lights then we cyclists do. I think, he might have been referring to my helmet mounted light. Given that it's power button is mounted on top of the light itself and it's on my helmet how am I/we suppose to shade our eyes from their lights and reach up and either dim or turn our light off and still maintain control of our bikes?

Sadly, I think that his "logic" is/was that because in his mind that the light that I was generating was "too bright" that it was okay for him to use his lights to "pay me back." Which is really just sad.

I have a couple of questions about your comment that you "routinely encounter riders whose lights light up my head and shoulders". How do you know? The very few cyclists I encounter are either riding in the same direction as me or riding in the opposite direction on the other side of the road. In the former case, I couldn't tell if they are lighting up my head and shoulders since they are behind me. In the latter, their lights are too far away to illuminate me at all. Even on those rare occasions where I use a bike path at night (almost all of ours are closed after sunset) and I encounter another cyclist on that path (a still rarer occasion), I couldn't tell you if my head and shoulders were illuminated because I'm looking at the road and not checking to see where his light hits me.

I observe where their lights are aimed by looking at where their lights hit the ground. I have yet to see anyone who doesn't have a pool of light 15 to 20 feet in front of them. That includes people I have overtaken, people on the other side of the road, people who have high intensity lights and people who have low intensity lights.

A helmet mounted light is meant to be mobile and pointable. It's the whole reason for using one. Of course you are going to see it moving around. As I stated before, I don't use blinking lights but I do use a helmet light. I point the helmet light into corners so that I can see where I'm going better. I point the helmet light off the side of the road so that I can see objects that might cause me injury. I point the helmet light down to illuminate road obstacles and I point it up so as to get an idea of what is further out than my lights are aimed (particularly helpful when riding on darken streets with ice build up). I point them way up to trigger camera operated traffic lights. I even, rarely, intentionally shine them in the eyes of motorists but only when I feel that my safety is at risk and only as a last resort.

Find some of the pictures and videos that mechBgon does in terms of lights. It's very illuminating. Here's one comparing bicycle lights to car lights

#!

Modulation can convey concepts like "im braking now", "Watch out for deacceleration"

Thank you - I did not do the calculation, merely repeated what I had been told (I shall in form the training centre of the error).

That said, the point still stands that before you have even started braking, you will have still travelled a fair distance - and that is presuming you are paying attention and are not driving under the influence of drugs (prescription or otherwise) or alchohol.

Then you have the breaking diatance to include which varys on the road surface and weather conditions.

On my daily commute, I routinely encounter drivers who take my right-away, cutting me off, and dam right coming right at me from lack of SEEING ME, or just don't think I have any right to the road. This is vastly different from you getting lights shined in your eyes making you highly uncomfortable. These drivers who are taking my right away, cutting me off, and almost running me off the road, are endangering my life, period.

Again, I challenge you to look up the numbers on WHOSE predictcament is the worse? The shining of the lights in drivers faces, or not being seen and endangering the cyclist's life? On my motorcycle, I for one, have seen many a car/cage jump back away from cutting me off, taking my right away or coming close to knocking me down, because they SEE MY LIGHTS!! This is a fact I have experienced, many, many times!

Lights on bicycles are LIFE SAVING. IMO, that is their number one job. Nobody, or at least they are in the minority, is aiming lights purposely at bicyclists and car drivers. And those THAT have lights AIM at bicyclists and car drivers, whether on purpose or not, is NOT LIFE THREATENING, as with the cars taking the right away, and cutting off bicyclists.

As a law-abiding-citizen, I hear a lot of complaints from bicyclists and their cousins, motorcyclists, that car drivers in a big ratio FAIL TO SEE THEM, therefore, making them take highly dangerous evasive action just to survive!

Speaking only for myself, I don't want to put myself in the position of somebody telling me, my love ones, and/or the police, after I am laying flat out on the ground "I didn't see him"...

As far as attracting legistative attention, I am all for that. I know in my state, all the legistative attention is going PRO-BICYCLIST. Not say cyclists are all saints, the fact of the matter is, more cyclist are getting put down by cars not seeing them, then cyclist causing mayhem. IMO, this is a fact.
I am all for self-regulation, but as you and I both know, there are going to be some bad apples no matter what. Most cyclists with good bikes and good lights, chances are these are responsible cyclists.

I think your post even proved my point better. Check out your legistative docket, and I am sure you are going to see more pro-cyclist laws being proposed or enacted, then laws aimed at bicyclists. Just my opinion... :beer:

:thumb: :thumb: :thumb: :thumb:

Sheesh, I know one thing, that vid is going to make me dish out the dough and get one of those Dinottes!! I tell you that!! ;)

Also, that vid shows it all. Even that bright Dinotte is no way near as intimidating as the car's bright lights. Also, the vid states a fact I said long ago as pure common sense, and that is NOT TO LOOK AT THE BRIGHT LIGHT. The vid said "and you know not to look at it".. But, some seem not to know that!! :D

Regulating dangerous headlight beams is pro-cyclist legislation, it protects safe and reasonable cyclists from the damage caused by hazardous lighting.

Or course it is "pro-cyclist" legislation, just as I mentioned in my previous post. Regulating cars headlight beams, just like in the video would be a great move to make cyclists more safer. As one can plainly see, car high beams are about 20 or 30 times more dangerous then bicycle high beams. Also, there are about 10k to 20k or maybe more cars to every bicycle on the road, so I know the legislation is aimed at the cars. If they are not, those elected officials will be seen as anti-bike, which will be the truth..

BTW. Happy New Year to you.. :beer:

As noted earlier, car high beams are already far more regulated than bicycle lights -- many bicycle headlights would be flat-out illegal if used on a car, motorcycle, moped, or scooter.

Equality is not discrimination.

They don't legislate against discomfort! They do legislate against danger. In addition, your view/opinion although valid, is in the minority. That is why you don't see an uproar against bicycle lights. What you see is the push for better lighting for bikes to be seen and to see. With the high cost of gas along with its pollution problems, opposed to health benifits and no pollution of the bicycle, improvements of the whole bicycle spectrum is on the rise.

As a law-abiding-tax-paying-citizen I am expecting my elected officials to enact laws that will make the roads safer for bicyclists. I am fortunate to be in a state, where my elected officials do just that.

My point exactly -- 1,000 lumens of tight conical beam aimed into oncoming traffic isn't discomfort, it's danger, and already prohibited on any vehicles other than bicycles.

Our point exactly! ;) And the reason it is not prohibited on bicycles, is because on bicycles it is not danger. Also, it is your opinon of 1000 lumens etc, is danger. Is it more dangerous then people hitting bicyclists because they didn't see them? Laws are enforced on their danger ratio. Example, murder is enforced and the penalty harsher than a traffic ticket. Also, dangerous actions are recorded. How many accidents are caused by so-called illegal bicycle lights opposed to bicyclist being run over, injured, and/or killed because the drivers didn't see them? Check those stats.

I am quite sure the answer will support the reason why bicycle lights are not regulated. :beer:

man, you'd think you guys could stop the pissing contest with the start of the new year....

In Texas, I think that the blinking front is illegal for a couple of reasons. 1) Theoretically, only fire, police, etc should have blinking white lights forward when on the move. 2) Devices which give you an automagic green light are illegal. As I understand it, the central white xenon on fire trucks and ambulances is the "identification light" for the sensor to give that vehicle the green. Having a flashing front white could be construed as having a device that would possibly override the traffic system.
I only blink in the day so that motorists will hopefully see me. At night, I want the solid because I want to see as well as be seen.
I am also fully aware that unlike Arkansas, Texas does not seem to enforce the color codes and I see reds, blues and flashing whites on all kinds of non-official vehicles.