Temporarily blinded driver results in either case, so it doesn't matter. Oncomming eyes are those looking toward you.

I can really comment on anything I want! By the way, have you ever measured your light beam out where you have it pointed at the ground? You might find the hot spot isn't where it appears to be when observing it from the source location.

You must ride a fixie, because that's some pretty serious backpedaling! If it was a joke, why the vehement defensiveness about it?

And I didn't take that as an insult, I offered an alternative opinion. It was your ridiculous use of a laser beam to illustrate headlight divergence, along with the many other misstatements you made in that thread (and continue to make) that led me to throw an insult your way. Get over it.

Let's stick to the OP's topic and end the bickering, please.

I have been beamed in the eyes by helmet mounted lights, while behind the wheel, usually sitting at a stop light as the cyclist looks around and/or stretches his neck. A few of those times it was bright enough for significant afterimages that remained for more than a block. Maybe it's my work with light that led me to notice it, but that work also shows me how incredibly powerful LEDs are getting fast.

Maybe all bike headlights aren't dangerous now, but many are and most soon will be.

I don't have to get out a yard stick to measure where the hot spot on the light is. I can see it, any rider can. Since I can point the light anywhere I want, I can see where the center of the beam is quite easily. It's not like the most intense part of the beam is off-center:rolleyes: At least not from a parabaloid reflector. Even in your tests you talk about the center of the beam being the most intense...as it is for any light that uses a reflector to concentrate the beam. Elementary optics.

I'm sorry:o I was trying to answer MorganRaider's question about depth perception and helmet lights and got drug off into a repeat of earlier arguments. I apologize.

You see what you think is the center of the hot spot. Sometimes optics aren't as "elementary" as appears to the casual observer. Identification of the location of the center of the hot spot is often way off when judging by the reflections off irregular, grazing incidence surfaces from the source location. Try adjusting your headlights by your method on a wet street, a dirt trail and dry smooth pavement and you'll see what I mean. But you probably won't. That's the overconfidence I mentioned.

And no, "the most intense part of the beam" can certainly be off center with a parabolic reflector in use if the source isn't in exactly on the optical axis of the reflector, which is typical of many lights. Roll your eyes when you know what you're talking about.

Just how many different people have to disagree with you in just how many different threads before you STFU with all the bad info you like to spread? What exactly are you trying to achieve? Go to A&S if you are looking for an argument and let us discuss lights, because you know, we actually use them daily.

Keeping helmet mounted lights on the trail, where they belong. Making cyclists aware of the ramifications of pointing their very bright headlights into oncomming eyes. And making the point that more light isn't always better. That's it.

Jaa, the ramifications of being seen by cars and being able to control where your light is pointed. :rolleyes:

You truly sound like a nutter who can't even fathom why anyone would want to do something different than you do. Amazingly all of us who use helmet lights haven't had the horrible reactions or incidents that you seem to think will occur. Why is that? Could it be that you're actually wrong?

It's simple; if you don't like helmet lights don't use one, but don't go around intentionally spreading bad info as it helps no one but your ego.

Before this thread is closed because of posts like 39 and 41 above, I want to point those interested to the big Magicshine thread right here. You'll see testimony about oncomming observers commenting that they "thought it was a car" comming toward them. That's less than 400 lumens in real life. What do you think >1000 lumens would look like? With half on the helmet flashing you in the face because the startled rider looked right toward you for a moment, right as you're about to pass them.

I was waiting for the dust to settle, but that could be a while. ( No offense guys.) I have read a lot of good points and ideas for alternate options. I really appreciate everyone taking time to reply and value the vigorous debates. Here is where I am headed for now.

1. Run with the Magicshine light on handlebar. I have used it once and find it pretty good. 100% of my riding is on a paved trail, currently covered in leaves and thru the woods. It can be very dark. I would like to have more light, both peripherally and a longer spot throw down the trail.

2. Wait for the CREE technology to come out later this fall and see what new offerings mfg's may have.

3. Still need a helmet light. Here I am leaning towards moving the M-shine light to helmet when/if I find a new light for handlebar. I like the stella 200 except for the large battery. I guess that's the trade one makes for the 5 hrs of available power.

I have been on 3 night rides on this trail, about 20 miles each time and have yet to see another cyclist, I have had trouble picking up people in dark clothing walking their dogs or the occasional deer on side of the path. Also there are only 3 road crossings with not much traffic so not sure shining light in motorist's eyes is an issue. Not that I would do that anyway. I do like the idea of flashing a beam of light across the car's path or hood to get their attention. Now, I may need a helment light for the smart arse with the orange safety vest who sits on a bench downtown at the end of my ride and makes stupid comments to me about being out so late. :notamused:

Thanks again for all your input !!!

Sorry Chad but this can't go unanswered.

RR, you are trying to win an argument by making stuff up. A paraboloid reflector sends the light out in straight lines from the focus of the paraboloid. Elementary optics. If you aim the light parallel to the ground at a target, it's pretty easy to see where most of the light goes. If you aim the light at an angle to the target the most intense part of the beam is still going to be near the center of the beam. Since you know where the highest density of light is while aiming it parallel to the ground, you can still see where the highest density of light is going to be when it inscribes an ellipse on the ground. Yes it will be elongated and the elongation is a function of the angle of the light of the light on the bar to the ground. However, the most intense part of a beam from a conical light source is still going to be at the optical axis of the reflector. And it is easy to see where that point is. All you have to do is look.

Reflectance isn't going to have much to do with determining the highest density of light, either...other than telling you where it is. Because we don't ride on mirror surfaces, any light hitting the ground and being reflected off is going to be either scattered (hitting all those surfaces that make up the road) or mostly absorbed (hitting a sheet of water). Even then the angle of incidence is going to throw the light off in straight lines (not concentrated like you'd get with a paraboloid mirror), so the scatter is even worse.

Where do you think the most intense part of the beam is going to be? If you have some kind of other optics where the light doesn't travel is a straight line...without a giant gravity source to bend it...from the source, let's see it. Let's remember that we are talking about a light source sitting at the focus point of a paraboloid shaped reflector here, i.e a normal bicycle light. No lenses.

Why not just do another Magicshine for your helmet. Relatively cheap light and Geoman has a helmet mount. At least get the helmet mount and try it on your head.

Agarose2000, others and myself do caution about using helmet lights...and bar lights for that matter... around peds. Turn your head away from them as you approach. You can turn your head a long ways to the side and still see well enough to continue on your way. Even while doing that, I try to ride as far over as I can from peds so that the main part of my beams (handlebar and helmet) isn't directed straight at them.

I really am more considerate than you've been lead to believe:thumb:

I agree with you on this bit, but that's because they're using standard helmet lights with a narrow beam!


I would actually agree with you that *if* you were passing oncoming cars from 2 feet away that's probably true - but as other people like to point out, you're never really in that situation with cars on your bike. They're over in one lane, and you're 10 feet away in the other lane, somewhere on the right side of your lane.

The OP asked about biking down a well known bike path, however. On the bike path, you *are* passing other riders coming at you 1-2 feet away. Being that your light is now at the level of their head, and you're point it right next to them, it's practically impossible not to hit them in the face with it *if* you have a broad beam. It can be pretty annoying even with a narrow beam if you look right next to them. It's particularly worse if it's an unlit path with no streetlights providing light off to the sides.

Now add in the fact that you already have a broad beam on your bars, and there's not even any reason to run a broad beam on your helmet.

This has gone way off-topic and evolved into a helmet light pro/con arguement.

You all will need to learn to agree to disagree on this point, otherwise infractions are going to start being given for name-calling and insults.

Thread closed.