Gresp15C

I submitted an idea over on the commuting forum:

https://www.bikeforums.net/commuting/...headlight.html

This works quite well on my CatEye parabolic reflector light. It reduces the overall output of the main beam by what I think is probably an acceptable amount, but blocks the annoying direct beam from the LED.

Note that my main interest here is curiosity about the technology. I'd like to see if I can improve it.

rscamp

For riding in traffic, bright bicycle lights need a cut off for the filament/emitter and an appropriately shaped reflector just like low beams on a car. It is that simple.

cyccommute 

You really need to read the link you keep posting. Candela is used to define lumens and lumens are used to define candela. They are, in fact, inversely proportional. That's not incommensurate, aka as disproportional.

Or you can use lumens. Either works.

Well, you did say it was "close to square". There is no other geometric form closer to a "square" than a rectangle. Either way, the light coming from any focused broad spectrum light source is going to propogate in a cone. Even car lights with cut-off on their beams are going to propagate from the lamp in a cone. The sharp cut-offs on current lights used in automobiles still appear as to cone to an observer.

The older car lights had similar upward spills as the Magicshine lights. They are simple reflectors with some diffusing molded into the outside lense. When driving I was taught not to stare into them. I do the same with bicycle lights.

The battery pack is the limiting factor. You can have enough power to run two Cree emitters for a short run time or you can cut down the output of the lights to get longer run time.

The light output didn't "drop". It was never high to begin with. But the lights were incredibly cheap so I'm not out much and I can use the battery for other lights.

Gresp15C

I think we may simply have irreconcilable views of things like physics and math. Have a nice day!

cyccommute 

Reflector technology goes back a lot further than the 1890s. I'm reasonably certain that the Greeks had parabolic reflectors and I think I read something once about ancient Egyptians having parabolic reflectors.

Shaped beams weren't unknown in the 1890s. It's not like someone just discovered that reflectors can be shaped. They are, however, expensive to produce which drives the price up.

As for "we should all use them", the question is why? Bicycle lights aren't a problem for drivers. If you were to ask drivers if they have a problem with bicycle lights, most of them will look at you like you have two heads.

cyccommute 

I think both are on my side. A lumen is defined as cd⋅sr or candela times squared radian while a candela is defined as lm/sr or lumen per square radian. Math says that is a inverse proportionality.

noglider 

A person should use a shaped beam unless that person is as smart as @cyccommute is.

Does that cover it?

wphamilton

It seems like an improvement might be to use a mirror instead of tin-foil, near the emitter or at least near the parabolic focal point. I happen to have bought some small square ones from the craft store (so I could go full Fred with various goggle mirrors) so I think I'll experiment with your idea on my clone light.

My headlight has an accidental hood - I drape a commuting bag over the top of the drop bars these days and needed something to keep the bag from hanging down over the light. The hood and my beam-shaping dispersal lens together do a pretty good job of making the light more friendly.

dwmckee

Yes, very simple for those that can understand it. For a lower-powered light you can get away with it but for very bright ones, they should not be used as headlights on public roads.

davehbuffalo

I got the Ixon IQ with batteries and charger for $80 from Peter White. Throws the light where I need it. Gets my vote, but I guess some people need something brighter. If I needed more light I'd probably just get another.

dwmckee

By 'older' if you mean pre 40s when headlights were not very bright maybe (that was before they thought seat belts were an important safety device by the way), but really anything you likely to see on the road now days has a modern shape technology with a cutoff.

There is nothing even remotely close to a MagisShine out there approved by the DOT for motor vehicle use. They are considered a hazard and are not legal for a licensed vehicle.

dwmckee

I think that was the original reason for the post wasn't it?

dwmckee

C'mon Cycocommute! Join the club; we want you on our side! Add just a few more facts in that vast database of information you have stored up there. Folks have presented quite a few reasonable counters here that are worthy of consideration. Please consider assimilating all of this and consider we might be on to something!

Gresp15C

Good idea. I'm also toying with the idea of adding some sort of prismatic element that turns the offending light into side spray. All for fun. My main motivation at this point is curiosity, as I have a satisfactory light source for the present moment.

Heaven forbid I might buy one of those fancy pants lights, just to experiment. I had two of the CatEye lights, and one lost its life because the battery leaked and the acid etched away the reflectorized coating of the mirror.

zacster

As a driver in a place full of bikes with all the various lights, including Citibike, I'll have to say I don't ever much notice bike lights. Every now and then I'll pass by someone in the bike lane with a super bright light, and I'll only notice because I'm curious to see what it looks like. Brooklyn streets are sometimes crowded with bikes too, and only the taillights seem to matter. The only time a headlight ever seems to catch my eye is when I'm pulling out of a parking spot. Oncoming lights on the other side of a two way street aren't noticeable. Compared to a car light they look like pin-lights, and given the sodium vapor lamps everywhere, they don't really illuminate much. Even my Cyo with the sharp cutoff and wide spread doesn't add much to the lighting of the pavement in front of me until I get somewhere dark.

It is only as a cyclist facing another cyclist that they have ever bothered me. I bought my Cyo premium more as an experiment than anything else. I love the light it puts out, I know it doesn't shine up, but nobody but another cyclist with their own lights ever notices.

cyccommute 

No, it's simplistic and fraught with problems. As I've pointed out above numerous times, cost is a very large barrier. Of the lights currently available, the ones with cut-offs are expensive, between 2 and 10 times the cost of the Magicshine clones. Even low intensity lights "be seen" lights like the Planet Bike are more expensive and have much lower outputs than the Magicshine clones. I would rather have cyclists using poor (to you guys) lights than no lights.

I don't know how old you are but lights didn't look a whole lot different from the 1920s until the 1990s. Lights with cut-off on the upper part of the beam have only seen wide spread use recently... within the last decade. Again, I have 3 vehicles within my family that don't have "modern" headlight beams with a sharp cut-off. The 49 Dodge lights mentioned above have a square beam but that's not a "sharp cut-off"

No, it wasn't. Bat54 mentioned bicycles and pedestrians but not cars. I took his comments as talking about bike path use which, again (and again and again), I happen to agree with. But that's even for you guys with cut-offs. Essentially lights of any kind and output don't belong on narrow bike paths where pedestrians are moving about at night. Many bike paths are also wildlife corridors and habitat and we should leave them to the night.

Why? There is no reason. See below.

Exactly what I've been saying. In 30 years of night time riding, I've had a motorist flash his lights at me...and that was when I was using lights that put out more than twice what the current "bright" LED puts out. The beams I used on those lights were a similar size as the LEDs with more light coming out the front. Bicycle lighting just isn't the issue with motorists that some make it out to be.

loosenit2

Agree that cyclists should adhere to the same rules for safety and courtesy. Not to hijack the discussion but I find that less than 50% of cars approaching bike at night will dim their headlights, most simply leave the high-beams on as they approach. I find this is blinding to me as a cyclist.

Garfield Cat

Speaking of battery packs, what about the internal cable housing used these days and the electronic shifting by Shimano and others? Will we see battery packs going into the seat tube by way of some kind of cable housing that's already there?

krobinson103

I prefer single battery flashlight style ones. Once you start putting batteries inside the bike you need specific packs. I stick with aaa/aa and liion single cells. I can get those most anywhere if my supply is drained and my solar cell can't recharge them fast enough.

wphamilton

I messed with it a little last night just manually placing the mirror near the emitter. While it did block the emitter directly the reflector became intensely bright, too bright to look at so it's hard to tell if it made much difference. I'll need to make some kind of bracket and try an a-b test on the bike to know if it's worthwhile.

cyccommute 

I doubt it. I'm not sure I would want that anyway. Cables and batteries for lights may look...well...fredish, but they offer a lot of flexibility. One of the main reasons I don't run generator lights (there are others but that's a different topic), it that I can take two light sets off one bike and put them onto any other bike I own in a matter of seconds. I can use my helmet light on any of two helmets I have set up for night riding as well. Putting the cables and battery in the frame would be a limiting as generator lights, in terms of moving from one bike to another.

There is also the issue of batteries and temperature variation. Battery chemistries work best under somewhat limited temperature range. Charging in very cold or very hot conditions as are typically found in garages is difficult and can cause harm to the battery. If as krobinson103 points out, you have a proprietary battery, it's more expensive to find a replacement.

Someone is probably working on such a system but I suspect that it would be cost prohibitive to build and sell. A generator light system would make more sense...and I'm not a huge fan of those. Frankly, I don't know how anyone making lights that isn't making Magicshine clones today stays in business. They may offer some refinements and nicer packages but at roughly $200 per lamp, it's got to be a really nice package. The lights with cut-offs...of which there really are few...can't compete either. The Magicshine clone with all its (supposed) warts, isn't going to go away anytime soon. And prices of from $10 to $40, they probably aren't going to change their optics either.

Kingpcgeek

I think everyone should buy a Lupine Betty R 10 at a measured 4280 lumens and call it a day.

no motor?

I'd agree with all of that except I rarely see anyone riding towards me. Otherwise it's a pretty simple solution for me and the others coming towards me on a 6' wide bike path.

I had a couple of guys want to follow me one night a few years ago. They may have had 2 dim lights for the 2 of them, but I think they only had one and it was hard to see them. We were all coming to one part of the path from different directions, and I heard them say something but couldn't understand it. They caught up with me while I was waiting for a light a couple of miles later, and guessed they were asking me to slow down so they could ride behind me and use my light.

Gresp15C

Maybe if you tilt the mirror, it will it the reflector and bounce to one side or the other, or towards the ground.

wphamilton

In theory the parabola shape reflects all light from the focus straight out (with minor spread), so we can't really direct the light beam from a mirror aimed into it. I did try tilting it various amounts but I didn't see it gain me much except for keeping the emitter out of the way of the reflected beam. The reflector lights up, very brightly. Now that I think about it, I really should look at it outside because it's probably a more tightly focused beam.