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Taillight Safety
I've been wondering about the modern bright taillights and how effective they are. It seems like the idea is to get a very bright LED. This seems to make a small bright point of light.
The idea behind taillights is for others to see you, not for you to see. Wouldn't a bigger surface area be better than the single bright point of light? I was out riding the other night and noticed that car taillights are not bright, but they have a much larger surface area to light up. The car taillights are easily seen at a wide angle. I have seen many bicycle taillights that are quite dim just a few degrees off of center. I'm starting to think that the brightness of the light doesn't matter, that the surface area and viewable angle are more important. Of course, too dim of a light and the surface area wouldn't matter. Does anyone know of any research done on this? |
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Originally Posted by SweetLou
(Post 13813197)
I've been wondering about the modern bright taillights and how effective they are. It seems like the idea is to get a very bright LED. This seems to make a small bright point of light.
The idea behind taillights is for others to see you, not for you to see. Wouldn't a bigger surface area be better than the single bright point of light? I was out riding the other night and noticed that car taillights are not bright, but they have a much larger surface area to light up. The car taillights are easily seen at a wide angle. I have seen many bicycle taillights that are quite dim just a few degrees off of center. I'm starting to think that the brightness of the light doesn't matter, that the surface area and viewable angle are more important. Of course, too dim of a light and the surface area wouldn't matter. Does anyone know of any research done on this? |
Most of the good ones are made to European standards which require a larger surface area as well as a relector. I recently put this
http://1.bp.blogspot.com/-y5QscnvQ5Q...0/IMG_1953.JPG Busch & Muller light with a brakelight functiononto my city bike. It seems really effective. Marc |
Originally Posted by 10 Wheels
(Post 13813342)
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Originally Posted by 10 Wheels
(Post 13813342)
The DiNottes have a floody beam pattern, it's not easy to get far enough off-axis that they're no longer an attention-grabber. If you have something like a SuperFlash or a Hotshot, then yeah, you'll want to aim them carefully to maximize their long-range impact. From group rides, I can vouch for a well-aimed SuperFlash 1/2W getting my attention from considerable distances, like 1km, in a sparsely-travelled environment. If you're in a scene like this one, however, you want to stack the odds as much in your favor as you can (skip to about 6:00): |
When I'm driving for work what stands out to me is the flash of a bicycle light and the brightness only helps me see it farther ahead. The other day I had to drive through a construction zone and there were hundreds of flashing lights so that the 2 a bicyclist had didn't really get noticed. Do you know what made him stand out? The reflectors on his pedals. My point here is that if you want to be seen you have to have something on your bike that makes it or you stand out from you surroundings and be noticed. This could be lights, reflectors on wheels or pedals, or a flag. (note: besides the 2 slightly dim rear lights, the cyclist was wearing dark clothing and after I passed him I could hardly find him in my mirrors because he had a very dim front light that did not blink at all. I was driving a bus and this is the kind of cyclist that can "come out of nowhere" and often times does on the college campus I work at. Scares the crap out of me!!)
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I've never had anything more pricey than a Walfart special, branded by Zefal, Bell or Schwinn, never more than $18 for a head/tail combo. I hit the tail light every time the sun's not shining, I pick the random flash feature every time; erratic flashes of light do not really allow the eye to disregard it. NEVER get buzzed when that light is on. I've even had drivers tell me they were glad I HAD the light, so they could see me.
None of these lights were a single LED, all were 5+; I wouldn't use a single under ANY circumstances. |
Originally Posted by 10 Wheels
(Post 13813342)
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Originally Posted by Chris516
(Post 13813838)
I agree, and disagree. Your concern about taillights, is why I not use taillights on my seatpost, back, and helmet. But also 'take the lane'. IMO the use of taillights and a 'proactive lane position', need to be done in conjunction with eachother. To have a taillight that would cover a wide is already intended in the manufacture of some taillights. But I don't think they work very well. A lot of taillights have a strobe(and/or flashing) function which would be beneficial, if people used it.
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Originally Posted by irwin7638
(Post 13813901)
Most of the good ones are made to European standards which require a larger surface area as well as a relector. I recently put this
http://1.bp.blogspot.com/-y5QscnvQ5Q...0/IMG_1953.JPG Busch & Muller light with a brakelight functiononto my city bike. It seems really effective. Marc |
My questioning is not if these single point of lights are bright and can be seen if right behind them. I am wondering if any scientific studies have been done about what is more effective in getting the attention of motor vehicle drivers.
I have noticed while out riding or walking my dog if a bike has a taillight, I can see it clearly if I am inline with the bike. Where I live, there are not many straight streets, as I see the biker go around a curve, the light get really dim. This is because the light is no longer pointed at me. I don't think I would have noticed it, if I didn't know it was already there. Car taillights also get dimmer, but since the surface area is so much larger, they are still seen clearly. Or maybe it is because the light is not as directional, I don't know. That's why I would like to know if there has been any research into this. |
Originally Posted by mechBgon
(Post 13813937)
Good illustration. Here's one of mine, shot at twilight (it was somewhat darker than the camera interpreted it). The big gun in this one is also a DiNotte 140, with Trek Beacon bar-tip lights (also marketed by Soma) and a SuperFlash on the end of the rear rack:
The DiNottes have a floody beam pattern, it's not easy to get far enough off-axis that they're no longer an attention-grabber. If you have something like a SuperFlash or a Hotshot, then yeah, you'll want to aim them carefully to maximize their long-range impact. From group rides, I can vouch for a well-aimed SuperFlash 1/2W getting my attention from considerable distances, like 1km, in a sparsely-travelled environment. If you're in a scene like this one, however, you want to stack the odds as much in your favor as you can (skip to about 6:00): Hard to say anything about the video though, it is just a comparison of different small point focused lights. The wide flood would probably be better though. It's like the street outside my home. The car headlights are very bright when looking directly at them. But they don't get my attention when looking at the businesses across from me. The large advertising signs are more noticeable. Looking at a headlight will hurt my eyes, but I can look at the "TJMaxx" sign all night without a problem. Even though it is much farther away than the headlights, it is more noticeable. Is this because of surface area or because more light gets to my eyes because it is not as directional? Sure, if all the light was pointed directly at my eyes, It would be even more bright, but would I notice it if I was 10 degrees off of center? |
Originally Posted by SweetLou
(Post 13814306)
I take the lane on most roads I travel, they require it. When the car is directly behind me, I think most of these bright small point lights work well, I have quite a few of them. But how about on a curve? The taillight is not pointed at the car in this situation.
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Originally Posted by SweetLou
(Post 13814364)
My questioning is not if these single point of lights are bright and can be seen if right behind them. I am wondering if any scientific studies have been done about what is more effective in getting the attention of motor vehicle drivers.
I have noticed while out riding or walking my dog if a bike has a taillight, I can see it clearly if I am inline with the bike. Where I live, there are not many straight streets, as I see the biker go around a curve, the light get really dim. This is because the light is no longer pointed at me. I don't think I would have noticed it, if I didn't know it was already there. Car taillights also get dimmer, but since the surface area is so much larger, they are still seen clearly. Or maybe it is because the light is not as directional, I don't know. That's why I would like to know if there has been any research into this. |
Originally Posted by SweetLou
(Post 13814327)
I do like my B&M lights. I like them more than my SuperFlash, Radbot or any other taillight I own. Even reflectors have a certain angle that they are effective.
Or, to boil that fancy talk down into simple photos... Example 1: note how the DOT plastic reflectors barely show, while the reflective tape is doing great at this angle. The TrimBrite tape is low-end glass-bead tape, while the DOT stuff shown here is mid-range prismatic Class 2 tape from Peterson Manufacturing: http://i240.photobucket.com/albums/f.../cue_sheet.gif Example 2: from my Cateye LD560 write-up, a comparison between reflective tape and CPSC multi-directonal plastic reflectors at a ~45-degree angle: http://i240.photobucket.com/albums/f...0/IMG_0066.jpg ^ control shot http://i240.photobucket.com/albums/f...TL-LD560/6.jpg For those who'd like prismatic tape, 3M Diamond Grade is top-notch for applying to flat surfaces, Reflexite V82 is great for single-axis curves. For multi-axis curves, cut Reflexite into 1cm strips. If you have fenders, they're a great place to slap on the V82 treatment. Your second video had some error, so I couldn't view it. Anyway, going back to the original topic, I've been behind people with SuperFlashes and other decent blinkies, and behind one or two with a B&M dyno taillight like yours, and find that the blinkes grab my attention even when I'm not looking for them... like, from blocks away. So my empirical finding is that despite the small surface area, they're effective. |
Originally Posted by mechBgon
(Post 13814833)
You can get much better wide-angle performance from prismatic reflective tape than from plastic cube-corner reflectors, because the plastic reflector relies on the difference in refraction between plastic and air (total internal reflectance), which fails beyond certain angles. Prismatic tape also uses cube-corner reflectors, but with a mirrored surface that reflects regardless of the angle of incidence.
Or, to boil that fancy talk down into simple photos... Example 1: note how the DOT plastic reflectors barely show, while the reflective tape is doing great at this angle. The TrimBrite tape is low-end glass-bead tape, while the DOT stuff shown here is mid-range prismatic Class 2 tape from Peterson Manufacturing: http://i240.photobucket.com/albums/f.../cue_sheet.gif Example 2: from my Cateye LD560 write-up, a comparison between reflective tape and CPSC multi-directonal plastic reflectors at a ~45-degree angle: http://i240.photobucket.com/albums/f...0/IMG_0066.jpg ^ control shot http://i240.photobucket.com/albums/f...TL-LD560/6.jpg For those who'd like prismatic tape, 3M Diamond Grade is top-notch for applying to flat surfaces, Reflexite V82 is great for single-axis curves. For multi-axis curves, cut Reflexite into 1cm strips. If you have fenders, they're a great place to slap on the V82 treatment. Sorry, I linked to the middle of it, try 6 minutes into this... a scary 7-lane 45mph highway in rainy darkness, with strip mall lighting for a distraction. It takes some punch to really show up here. I think a steady dyno taillight with a reflector would make you a last-second discovery here. Anyway, going back to the original topic, I've been behind people with SuperFlashes and other decent blinkies, and behind one or two with a B&M dyno taillight like yours, and find that the blinkes grab my attention even when I'm not looking for them... like, from blocks away. So my empirical finding is that despite the small surface area, they're effective. |
Originally Posted by mechBgon
(Post 13814833)
You can get much better wide-angle performance from prismatic reflective tape than from plastic cube-corner reflectors, because the plastic reflector relies on the difference in refraction between plastic and air (total internal reflectance), which fails beyond certain angles. Prismatic tape also uses cube-corner reflectors, but with a mirrored surface that reflects regardless of the angle of incidence.
Anyway, going back to the original topic, I've been behind people with SuperFlashes and other decent blinkies, and behind one or two with a B&M dyno taillight like yours, and find that the blinkes grab my attention even when I'm not looking for them... like, from blocks away. So my empirical finding is that despite the small surface area, they're effective. I think most of us would agree that if within the focused beam of light that the single point light would be brighter and easily seen. But if we are outside of the cone and only getting a bit of light, would the non-focused light be better? Think about a laser. If it is pointed at your eye, it would be very bright. But, if it was pointed at your chest, you wouldn't see the light emitted by the laser. Now, if the laser light was diffused and used to light up a piece of paper, it wouldn't be as bright as the laser in the eye, but the paper would be easily seen at many different angles. |
I see what you're saying. It's a pity I never got around to doing firsthand subjective comparisons of my DiNotte 300R to my Hotshot. The 300R is an all-out flood beam, the Hotshot is focused like a SuperFlash. Their actual light outputs are similar (according to my camera's light metering) but one comes from a big target, the other from a small one.
If I get a chance, I'll hook up my old Nova BULL strobe head and take some daylight pictures/movies at ~100 meters comparing the Nova to the Hotshot. The Nova is a big target, about 1x4 inches, and looks like this at 100 meters in direct mid-day sunlight, whereas the Hotshot is the size of a SuperFlash. http://i240.photobucket.com/albums/f...0m_cropped.jpg On a practical note, personally I do notice lights like the SuperFlash from all sorts of angles in city scenarios. |
My tail light (mounted to my rear rack) has a single, very bright LED, with a lensing outer casing that improves visibility at off-angles. There are also two reflectors built in.
I think the difference between car and bicycle lights is the closing speed. Under most conditions, two cars are going to be doing close to the same speed, so long distance visibility isn't as important since the closing speed is low. Compare that with a relatively slow-moving bicycle and a car, and it's clear that the higher closing speed requires better long-distance visibility. |
Well, if you want big, there's always the FoxFire Commuter Tail Light. Had I remembered about it existence when I outfitted my winter bike with 2 additional lights, I might have tried this. I saw a demonstration on YouTube where it appears to be as bright as a car's brake lights and about the same time.
I hear it eats batteries though. |
Wow, I have never heard of the Nova Bull, it looks nice. mechBgon, testing would be nice, especially if you are able to do it at different angles. The only problem is that unless the lights put out the same amount, it would be testing the lights and not the surface to point aspect.
I'm not really saying that surface area is better than point, but I have a hunch that it is. To me, it seems like the brightness doesn't matter (as long as there is enough) only that enough light and big enough gets to the driver. That is why I was wondering if there were any known tests. How do companies decide which to make? Do they just make a bright light or do they do testing? I would like to see some real scientific reports on this subject. It could be very interesting. |
I want you to look at MY Tail Lights:
http://i134.photobucket.com/albums/q...e/IMG_1292.jpg Notice that I have set up orange road cones, one each in front and behind the bike. Note how the rear cone has two shadows, from the two tail lights. In fact, the cone is glowing from the light passing through it. I've also got an orange reflective triangle, between the tail lights. Let me show you another photo: http://i134.photobucket.com/albums/q...e/IMG_1291.jpg You can see the red light on the asphalt behind the bike. This is the kind of light you need for a tail light. These lights are 12v LED (Twelve Volt Light Emitting Diodes), Made by Signal Stat, they have thirteen LED's each, NAPA part number 1050. You can get them at an auto parts store, such as NAPA. These are what truckers use, and they are DOT legal. But I also use amber marker lights up front: http://i134.photobucket.com/albums/q...e/IMG_1290.jpg These amber markers were also purchased at NAPA, but they only have two LED's each. The Headlight is also an LED lamp, 6.7 watt version of an MR16 halogen bulb. All lights are twelve volts in these pictures. Current draw is so slight, I can run them an hour and a half, and when I plug the charger back in, the full charge light is still lit. |
I have the Planet Bike Superflash aimed straight back, and a Blinky 7 on each seat stay aimed slightly outward.
You could also try the RealLITE. http://www.reallite.com/RLHome.htm |
Thanks Dchiefransom, but I am not looking for a light. I am looking for data, research on which method is more effective.
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