Headlights, the first (brightest) one is solid. Sometimes I'll go with a smaller, dimmer helmet light flashing. Flashing does grab other people's attention; it is difficult to see what you're doing if it's your only light on a dim road.

Tail lights, I like to have at least one each. Supposedly the steady light is easier for approaching motorists to judge distances. Flashing does get more attention, though!

I've seen motorcycle headlights modulated by varying voltage to the entire unit, or by blinking some fraction of the LEDs in a multi-LED unit. It doesn't take much variation to make the light more conspicuous.

Strictly speaking, virtually any LED light with adjustable output are already using "variable power operation". LED are not dimmable, which means that all forms of reduced output are achieved by high-frequency blinking (PWM - pulse width modulation). While with muti-LED lights it is, of course, possible to vary the output by using only some subset of the LEDs (instead of PWMing the entire light), most headlights simply resort to PWM. Considering that PWM is a rather extreme form of "variable power operation" and that it is used virtually universally, I'd say that there shouldn't be any issues with variable power operation.

My own use of lighting is never based on the law. In general i use bike lights to be seen by others and to "see" the road or trail.

Typically this means that i use a blinking light whenever I do not need additional light to see my path.

How anyone can make this some sort "question" is a mystery to me. But hey, does the air go in the tire or should I leave it in the pump???

yepper, agreed. I'm sure you draw the line at using red or blue lights in the front as I do - but the blinking thing, I'm out in the boonies and I plan on having at least 2 WZ5's in front angled to 45 and 2 RZ4's in the rear also angled at 45 along with an amber flasher on each side. I will be running all of them on blinking as long as my trike is out of my garage - of course I ride primarily in the daytime....

lol. I think it's a question because blinking lights are illegal in some countries, so at the very least, some bureaucrats must've had some drawn out discussions about it.

I'm a firm believer in the blinky tail light in urban traffic. There's just too much going on visually for a solid tail light to attract much attention with traffic lights, street lights, car lights, lighted storefront signs, etc. I've seen more and more Euro-style bikes with dynamo powered fender or rack mounted solid (non-blinking) lights and I just don't think those lights stand out as much as a blinking tail light.

I set my tail lights (a PBSF Turbo and a Radbot 1000) to blinking. I figure I have enough reflectors (on the fender, on my backpack, on my jacket, on my ankles) that I don't need to set the tail lights to steady. I one of my headlights on steady and another on blinking... I have 2 x PDW Cosmic Dreadnoughts. For early morning commute I have one headlight on blinking mode.

While there are advantages to using PWM, LED's are most definitely dimmable. Brightness is a function of current.

Blinking lights on bicycles are illegal in several U.S. states, too, but there's very little enforcement. Some states have taken the time to amend their laws to allow blinking tail lights, others just look the other way. (For those who remember them, early moves to legalize blinking lights on bicycles were prompted in part by the popularity of the old Ampec Belt Beacon, whose incandescent bulb blinked once a second, just like a construction barricade flasher.)

Many more states continue to ban blinking headlights, but again, there's very little enforcement. Blinking headlights are illegal in Washington State, for example, but I've never heard of a single rider getting a ticket for one.

And there are gray areas -- is a light on your helmet legally a light on your *vehicle*, for example?

Part of this is the difference in road culture between the U.S. and most of Europe. In the U.S., bicycles are still an exception, a very small fraction of traffic. Many drivers drive down the road not expecting to see a cyclist, not watching for them. Where cyclists are a normal part of traffic, a steady light and pedal reflectors are more than enough to warn an attentive motorist.

Interesting. I didn't know that there was that level of jurisdictional regulation. I should probably look up the provincial regulations for bicycle lighting. I have no idea.


I wonder what evidence is considered when such regulations are made, if any. Britain, for example, had forbidden flashers but in 2005 began to allow them.

Agreed. Even in a congested downtown like Toronto's, where cyclists are ever present, motorists aren't especially aware of their presence (although many cyclists cavort about after dark with completely inadequate lighting...)

Thats good, it'd be nice if more states allowed for that.

I guess I've been lucky - I've never had anyone tell me to "quit running a blinky." Most of the cops I've actually talked to gave me the impression to "do whatever you want if it makes you more visible."

Strictly speaking LED output is the result of "power." However, the role reflectors and semi-conductors play "upstream" of the glowing diode should be considered. I'm hardly an expert but i have studied (or played with) with quite a few lights while measuring both voltage and current. (brightness is the product of both)

In this thread - the subject is human perception of light and lighting. And again, I don't see how choosing to use a bicycle light mode can possibly be confusing.

I'll see your "hardly an expert" and raise you an electrical engineering degree. You may have played with lights and measured voltage and current, but you don't seem to understand how a PN junction works. I suggest reading up on the theory - it's not too complicated, and it's interesting stuff.

LED's are current-controlled devices. You vary the brightness by varying the forward current. They have a fixed voltage drop (well, it'll change a very small amount with forward current, but that's a property of the diode, and is not controlled by the circuit; it's a small enough variation that it's usually treated as if it were fixed). Trying to drive an LED with a voltage source is a good way to destroy it. Look up the I-V characteristics of a diode and you'll see why.

Going back to the original question - both is the answer. However, I disagree with the way some people place their lights.

The problem is not how bright a light is, but rather the angle of attack. As a professional driver, I am fed up of being blinded by cyclists who aim their lights AT the drivers. This is dangerous. The lights would be just as visible, and a LOT less dangerous if aimed down a bit as the driver approaching the cyclist would be able to maintain visual contact with the cyclist at all times.

I am currently running LED dynamo powered lights front and rear mounted at the fork crown and on the rear rack - and steady.

LOWER than these I have Reelights and Pedalites which are all flashing, but do not blind oncoming traffic.

Myself I run solid all the time because I have a vision problem that blinking lights irritates. Basicly the blinking light throws off my depth perception and is very dangerous if its my lights or another cyclist lights it causes me problems. I have the same problem with driving a car and being by a bike with blinking lights. I'm also unable to wear most tints of sunglasses because this vision problem its ironic because I have better than 20/20 vision in stable light.

Trains sometimes move a second headlight beam up and down. If that wasn't mechanically difficult, that would be a good way to make a thin strong beam much more visible.. by moving it vertically up and down to cover the entire forward area, from close to very distant..

Now I find that quite interesting because when my pupils are dilated, and also when I have this episodic eye problem that Ive had a few times, suddenly, my ability to perceive flickering in lights changes and invisible levels of flickering become not just visible, but annoying.

Okay, I hve a question for you, can you tell two lights apart, one flickering, one not, at some times, but NOT at others?

When that is happening to me, I can. For example, I will walk into my eye doctors office.. and some of his florescent ceiling lamps will be annoyingly flickering, others wont be. When I am there and I'm not having this probelm, I dont notice it. Also, some of his employees, like me notice it, others dont.

Also, dilation makes me notice it. Scopalamine or atropine or whatever is in them.. Beladonna. deadly nightshade, whatever.

I think this is some undiagnosed vascular issue - it typically accompanies extreme eye pain, one of my eyes feels like its bulging out, and I get sort of tunnel vision in that one eye. Its one of a number of strange health issues that I have, and I am trying very hard to get my HMO doctors to look into them, but since I'm still ambulatory, I think they see them as a low priority.

Whats helped me substantially are phytonutrients. Resveratrol, quercetin, curcumin.

(assuming they are fresh, stale phytonutrients lose potency)

You may want to do whatever you can to improve cerebral vasular flow and reduce platelet adhesion. (VCAM-1)

Fish oil might help too. You can't get too much fish oil. (Get a popular brand, like the Costco house brand, Kirkman I think it is, its been tested and shown to be lower in mercury than most smaller brands)

Unless for some reason you are taking blood thinners of have LOW blood pressure. Then you need to discuss that stuff with a doctor, if you have one. Also be aware that (although I haven't seen any literature specifically saying this) it appears to me that resveratrol by virtue of its lowering many inflammatory mediators substantially, may cause some important prostate - related (and probably lots of others) tests to be negative - like (if you're male, this is important) PSA tests I am almost sure would show negative while taking resveratrol, no matter what.

Important, I'm not a doctor and I am only speculating here, guessing, making hypotheses... etc.

Additionally, (unrelated.)

There is quite a bit of European reasearch showing that a yellowish headlight may in some situations be preferable to white or blue white light.

Whitefiretiger, I would strongly encourage you to make yourself familiar with PubMed and make a list of any unusual health phenomenon that you have and try to figure it out yourself, as best as you can. Things like that are often interrelated with a bunch of other things, symptoms come in clusters, so to speak. There may be a great many issues that cause your symptoms but you should make a list of them and work through them one by one evaluating their symptoms against your own and weighing their likelihood higher or lower based on your gut feeling.

Then, if there are any medical tests that you think you need, (be very sparing with them) try to get them. You may find that you have some easily curable issue.

You may even be able to cure yourself. Don't trust the medical profession to do this for you anymore unless you are very wealthy, they just dont have the time anymore. They pick arbitrary diagnoses out of a hat and stick them on people.

It would be impossible for them to know which diagnosis someone has in the time they spend so predictably, they are often wrong.

So, if you dont have a doctor, its not so unusual, many people who have doctors dont really have doctors, we are coasting on the health/wealth of the past.

My vision problem was caused by repeated "welders flash". I used to work in an auto shop and from time to time something would happen (like a new worker not warning before welding or the auto tenting mask failing) and my eyes would be exposed to welding (one time was so bad I couldn't see at all and any light exposure felt like my eyes were on fire.it took 3 days to regain my vision). My doctor said there's not much to be done to correct the damage and attempt at surgery to correct the problem would more than likely reduce my vision.

Now we are getting into an area where I might be able to find some stuff to point you at. Actually, I know there is something you can do.. (besides stem cell therapy)

You're here right now, so hold on for a few secs.. I am going to PM you also. I just saw something about this exact issue.

The French used to use yellow for their front fog lamps, but you can't buy those bulbs anymore.

Selective Yellow

This problem is compounded by lights with lousy beam patterns -- most high-powered bike headlights have a beam as round as a flashlight, so that at least 40% of the light is thrown away into the air or into the eyes of oncoming drivers.

It's a separate problem from flashing lights throwing a beam intense enough to cause disorientation, but the two combined are extremely hazardous.

When I am going down hill or when I am in a high traffic area I blink. Any other time I have it on steady so I don't run into debris or a large pot hole. And just for ****s and giggles, I have two red and blue flashing LED's that I put on one night and I rode past quite a few patrol cars -- none of them had a problem with it.

However, when I had the red, white and blue lights on, pedestrians and cars seemed to slow down and take more precaution when I was near them. One individual ran two stop signs, so I turned my lights on and I sped up. As I did this he proceeded to peel out like he was getting pulled over.

Illegal? Yes. Funny? Yep.

I do know of one local cyclist who was pulled over for impersonating an emergency vehicle -- he had bright red LED blinkers in front as well as behind (Two .5W Radbots each direction).

The officer let him off with a warning, but said that light combination was reserved for fire and ambulance, so he'd best not ride through town that way again. (Small town, 7,000 people, so there's a good chance the officer would remember him if he saw those lights again.)

Thats the big plus about inoled headlights, they have a different kind of reflector that creates a light beam that makes it possible to do that and not blind drivers. As far as I can tell, its unique. The LED faces up and the reflector is a portion of a parabola OVER the LED, facing out. Google them and you will see pics.

It works well.

The pattern looks like this

__________________
\ /
\ /
\_____________/
^ brightest at the top ^

Oops, the system doesn't maintain formatting..no   well, you get the idea..

The Philips SafeRide LED headlight does the same thing, a very sophisticated reflector design that produces a sharp cutoff and a beam that's progressively brighter towards the top, so you get more even lighting and don't have a hot spot right in front of your bike to ruin your distance vision. (It also doesn't have a blinking mode, just high and low intensity settings, since it's designed to be legal in jurisdictions that ban blinking lights.) The Philips has the LED emitters on top, firing down against the reflector, but again, not firing straight ahead with a round beam pattern.

You can see some great beam pattern comparisons at http://reviews.mtbr.com/2012-bike-li...pattern-photos

For commuting use, any light hitting the trees in those pictures is a complete waste, and any light hitting the top of the fence is going into the eyes of oncoming traffic close enough to hit you when they're blinded. I've compared the Philips SafeRide in person against much brighter lights with round beam patterns. Riding with the light, it does a better job of lighting the road ahead, and riding towards the light, it's very visible without being blinding.