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Thread: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

  1. #1

    Default Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    https://www.bike24.com/p2300708.html
    Lupine Rotlicht LED Rear Light

    The export model has 160 Lm. But the German "StVZO approved" model, which is all they sell in their own country, has only 40 Lm.

    Any German speakers here who can determine if the Germans have done any actual research into why a 40Lm max is desirable? For both day & night?

    And I wonder if foreign makers pay attention to their Euro standards for the beam angles of auto lights, and make their bike lights the same? Of course, a bike might not be able to supply as much power, so might be less bright.

  2. #2
    *Flashaholic* kj2's Avatar
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    AFAIK, it has to do with German law. Plus, anything brighter would/will be overkill. If they don't see you with 40lm, they won't see you with 160lm either.
    Bike lights can be powerful. I personally, am using a Lupine SL AF4 on my daily commute. That light has a lens, that provides a clean cut-off. When properly installed, other road-users won't be blinded.
    And the German version of the Rotlicht, also lacks flashing modes. Something that is prohibited by German law. Also prohibited in other countries, but many cyclist still use it...

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    Flashaholic Marcturus's Avatar
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by kj2 View Post
    AFAIK, it has to do with German law. Plus, anything brighter would/will be overkill. If they don't see you with 40lm, they won't see you with 160lm either.

    And the German version of the Rotlicht, also lacks flashing modes. Something that is prohibited by German law. Also prohibited in other countries, but many cyclist still use it...
    The legal limit is not (practically) about the flux, but about max intensity which TA 14b limited to 12 cd (30 cd for short-time signaling function a.k.a. braking.) So the reasons why the Rotlicht's StVZO version is less bright probably have to do with a lack of willingness to pay for another optic design, even more extreme-angled or inefficient, just to reach compliance.

  4. #4

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Marcturus is right, and what he says is really important, so please forgive my shouting: Lumens are the wrong thing to be talking about. What matters to the safety performance of a headlamp, tail light, brake light, marker light, etc is intensity, measured in candela at a specified location -- could be straight out from the axis of the light, could be 15 degrees left and 2 degrees up relative to the axis, could be anywhere within the range of about 60° left and right, 20° up and down. A lamp with a light source that produces more lumens is not necessarily better than a lamp with a light source that produces fewer lumens. It's all about how efficiently and effectively the light is focused and distributed.

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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by -Virgil- View Post
    Marcturus is right, and what he says is really important, so please forgive my shouting: Lumens are the wrong thing to be talking about. What matters to the safety performance of a headlamp, tail light, brake light, marker light, etc is intensity, measured in candela at a specified location -- could be straight out from the axis of the light, could be 15 degrees left and 2 degrees up relative to the axis, could be anywhere within the range of about 60° left and right, 20° up and down. A lamp with a light source that produces more lumens is not necessarily better than a lamp with a light source that produces fewer lumens. It's all about how efficiently and effectively the light is focused and distributed.
    Hello again to CPF, after a long absence... The proper way to look at any light that is directly to be seen, is using the light density in cd/m^2 but you also need a certain luminous flux (lumen, for the non-experts this is sort of the 'amount of light', though light is a flow so therefore amount is not really the right expression), or by specifying the emitting area, these are of course equivalent in that you need just 2 of these and the other follows.

    As to why cd/m^2 is important, it is because light gets sent out by an emitter of a certain area and received by the eye which uses a lens, onto an area in the eye. I've explained this in my 2015 proposed standard, in which I didn't specify exact details of light intensity etc. but using the ones from StVZO is mostly ok so the essence of my proposal was to show what needs to be in a proper standard both from a technical perspective and a perspective of making it understandable to anyone (within reason), so reasons for all requirements are an integral part of my standard. See:

    https://swhs.home.xs4all.nl/fiets/te.../index_en.html

    and for the explanation of why size matters, see section 1.0 and 1.3.

    Note that a lens is not a proper distributing optic! It changes nothing about the emitting area, though it reduces how much the eye will see of the total light sent out, if it's a wide angle lens. Also about the original question, 40 lumen is way more than any dynamo lamp and none of those are 'too dim'... As someone else said "If they don't see you with 40 lumen they won't see you with 160 lumen'. I can lower that: "If they don't see you with a few lumen as in say the Lumiring, they won't see you with a 160 lumen lamp".

    I could discuss more details such as about DRL, which similarly needs to be treated as a to-be-directly-seen light, as this is similar. So I will tell you a bit about this topic and the discussions I had with a researcher working on the new TA that should be about ready, finally, a long time after the changes in StVZO that got into effect mid 2017 (end of 2016 they were already approved), and since which the KBA and labs doing approvals have been using a mish-mash of standards. The 30 cd signal function has not been in effect I think for a quite a while, there was the option it seems to use that at the same time as the new brake light requirements which are brighter, but the KBA makes final decisions and they choose which rules to follow and they can deviate where needed from the rules. E.g they do not use the 3W rules of DIN 33958, only those of TA, i.e. a company can not choose itself which rules are to be followed for an approval.

    I tried to get the person working on the new TA to deal with point sources and other issues, but either he is not interested or constrained in what he can do, in any case he told me that there will likely not be a size requirement for bicycle DRL in the new TA (and in the intermediate rules being used since mid 2017 there isn't a requirement for emitting area either, i.e. they are using ECE's intensity but not the light emitting area, although the latter is also regulated in the ECE rules (for cars)!). I don't like DRL as explained in that standard and I think it was here on cpf that long ago I made the comment about visibility that you can question where it ends, i.e. there is a trade-off everywhere between safety and convenience. My comment was that you might as well install a water canon on all cars to spray cyclists and pedestrians, then they will certainly notice you! ;-)

    I gave this comment too, to the researcher in question, after he told me that his predecessor said "It's better to be annoyed a bit, than to be dead". I find such non-arguments not funny, so in return I told him my water cannon suggestion and the suggestion to lower the speed limit for cars to 20 km/h, then safety is assured! This is sort of a reductio ad absurdum to show that in everything there is a trade-off, and I don't see any evidence that DRL is useful, I do see that it distracts. DRL or pseudo-DRL (not separately approved DRL) in bicycle lamps is even worse, I told him that e.g. the Luxos should never have been approved. In any case, it seems he wasn't amused by my response, and what he then wrote showed me that he is constrained in what he can do. I then made the following page about inconsistencies and problems in StVZO/TA:

    https://swhs.home.xs4all.nl/fiets/te...istencies.html

    To end: I've not done much testing last few years, caused by a few things. One of those is that I've been very disappointed by the fact that there has been just about no progress in dynamo lamps since the Saferide 60, in beam shape and light colour with the still predominant and poor choice of cool white light in most lamps. I've been meaning to do some more testing of pedelec lamps and perhaps I will test the front wheel Spinup F12W-pro if there is enough interest (eg. enough people donating to buy buy one, I could then draw lots for one of those people to get it after testing). In any case, if you (the readers of cpf) want to see more no-nonsense and rigorous real-world testing of bike lamps and dynamos such as the Spinup F12W (instead of e.g. the things that GCN does on youtube, one video that I saw recently was as usual more about entertainment than having any substance), and possibly of more visits to bike lighting makers, subscribe to my youtube channel ( https://www.youtube.com/channel/UC8g...m7YfVqdX3VjQsg ), comment there, and if you are serious about seeing more reviews in the style that I've done before, consider supporting me/my site, see for that my website where I give a few options: https://swhs.home.xs4all.nl/fiets/tests/index_en.html

    I may start a new thread to get some input or support on how to continue, if there is not enough interest I will likely do only reviews of stuff I want to and already did buy for myself.
    Last edited by swhs; 02-05-2020 at 12:17 PM.

  6. #6

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Please explain your jargon: DRL, TA, ECE, KBA... ?

    "But wouldn't lowering the headlamp limit improve being able to see taillamps? And can it technically be done?"

    Reducing car headlight output will never happen; they will only get brighter. This is why tail lights need to be very bright -- so they are not obscured by other sources of light affecting the driver's eye. Especially when that light flashes and appears suddenly brighter then dimmer. The driver's pupil goes from very wide on a dark road, to suddenly constricted when a car comes over a rise with its bright's on. Then it takes seconds to adjust to complete darkness again.

    It would be useful to calculate the ability of the human eye to notice tail lights of a constant brightness versus the diameter of the pupil. And the maximum pupil dilation is very much smaller for older people vs young people. IIRC something like greater than 10mm to under 6mm as you age.

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    Flashaholic Marcturus's Avatar
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by lumen aeternum View Post
    Please explain your jargon: DRL, TA, ECE, KBA... ?
    In the context of this forum, TA is referring to an annex to a paragraph of StVZO; KBA is the German MoT's street vehicle regulatory office.
    If your search engine is down, some lurking and reading in the Automotive forum should help with the other two abbrevations.

    Quote Originally Posted by lumen aeternum View Post
    "But wouldn't lowering the headlamp limit improve being able to see taillamps? And can it technically be done?"
    I'm sorry, is this a quote or a summary?

    Quote Originally Posted by lumen aeternum View Post
    Reducing car headlight output will never happen; they will only get brighter. This is why tail lights need to be very bright -- so they are not obscured by other sources of light affecting the driver's eye. Especially when that light flashes and appears suddenly brighter then dimmer. The driver's pupil goes from very wide on a dark road, to suddenly constricted when a car comes over a rise with its bright's on. Then it takes seconds to adjust to complete darkness again.

    It would be useful to calculate the ability of the human eye to notice tail lights of a constant brightness versus the diameter of the pupil. And the maximum pupil dilation is very much smaller for older people vs young people. IIRC something like greater than 10mm to under 6mm as you age.
    No matter if the diameter is 6, 4, or less mm in two-way traffic, the supposed sudden pupil constriction is not the problem, but veiling glare is and the deterioration of vision due to age-related eye diseases can be. (Distracted driving, and speeding, are not a matter of old age.)

    Tail lights do not need to be "very" bright in clear weather, but need a certain amount of observably lit surface area in order to be detected and identified in time, amidst faraway lights and optical distractions like rain drops on a windshield or similar. Have you ever rear-ended any 1980's black Mercedes limousine because their functioning Euro tail lights were dimmer (in intensity and luminance) than your Rotlicht lamp or some $10 LED bike tail light? No, I'm sure you never did.

  8. #8
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by lumen aeternum View Post
    Please explain your jargon: DRL, TA, ECE, KBA... ?

    "But wouldn't lowering the headlamp limit improve being able to see taillamps? And can it technically be done?"
    Just as Marcturus, I wonder where this statement came from...

    Quote Originally Posted by lumen aeternum View Post
    Reducing car headlight output will never happen; they will only get brighter. This is why tail lights need to be very bright -- so they are not obscured by other sources of light affecting the driver's eye. Especially when that light flashes and appears suddenly brighter then dimmer. The driver's pupil goes from very wide on a dark road, to suddenly constricted when a car comes over a rise with its bright's on. Then it takes seconds to adjust to complete darkness again.
    Car headlamps approved via ECE rules (r113) are restricted in lux and lumen, and of course the light going upwards (above the horizon) is limited just as much as with incandescent lights so that has not increased from before Xenon lighting. Don't know what the rules are in the USA, but I have heard that they are more permissive.

    Cars going over crests is an issue but it's an annoyance, not so bad normally that you don't see anything. I've been blinded more by a too high aimed Edelux (I mentioned to a cyclist a few years ago that his lamp was aimed to high, we got talking and it turned it he had an Edelux), than by cars going over a bridge close to where I live (comparable to the crest of a hill). The issue is light emitting size... The smaller the lamp and thus emitting size, the more it will hinder, even blind you, similar to a laser, as the light converges again in the eye, in a very small spot if the original light emitting is a small spot ...

    Further the issue of night vision is rather small, after all, if you are riding at night you need to have a headlamp and if there is streetlighting that means even more light that your eyes get used to, so you will never need to get adjusted to total darkness...

    TA= technical rules used to approve active and passive lighting in Germany, for vehicles where ECE lighting is not required, which means e.g. bicycles, 25 km/h pedelecs, and e-scooters (via the new ekfv law from June 2019). It's similar to ECE and DIN standards in that it is the standard applicable to approving certain lighting and in that it is not freely distributable (which is bad, but what else than stupidity can you expect coming from politicians? (I mean this in the sense of the structures dealing with rules and standards, not the actual technical contents)).

  9. #9

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by swhs View Post
    1) Just as Marcturus, I wonder where this statement came from...

    2)...of course the light going upwards (above the horizon) is limited just as much as with incandescent lights so that has not increased from before Xenon lighting. Don't know what the rules are in the USA, but I have heard that they are more permissive.
    1) quoted from the document linked to in the OP.

    2) The US does not have the "euro style headlight" with the horizontal cutoff. Lots of upward spill. There is zero enforcement of headlight aiming or extra lighting being used. Apparant brightness is increased by using blue-er lights.

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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by lumen aeternum View Post
    1) quoted from the document linked to in the OP.

    2) The US does not have the "euro style headlight" with the horizontal cutoff. Lots of upward spill. There is zero enforcement of headlight aiming or extra lighting being used. Apparant brightness is increased by using blue-er lights.

    The original document linked to is bike24's sale page which does not list the question "But wouldn't lowering the headlamp limit improve being able to see taillamps? And can it technically be done?" in neither the overview nor fact sheet, at least not for me. Do you get to see a different page based on your location?

    And about the question from your original post:

    And I wonder if foreign makers pay attention to their Euro standards for the beam angles of auto lights, and make their bike lights the same? Of course, a bike might not be able to supply as much power, so might be less bright.
    In the EU there are a variety of standards for bicycles, mostly too loose. For cars it is ECE. In the German standard for bicycle headlamps they have different allowed lux ratings from cars above the horizon (at 10 m: 6.25 lux for cars, and 2 lux for bicycles), which, when you take emitting area into account, are actually quite similar...
    Last edited by swhs; 02-11-2020 at 10:32 AM.

  11. #11

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by swhs View Post
    Car headlamps approved via ECE rules (r113) are restricted in lux and lumen, and of course the light going upwards (above the horizon) is limited just as much as with incandescent lights so that has not increased from before Xenon lighting. Don't know what the rules are in the USA
    You don't appear to know what the rules are in Europe and the rest of the world where UN Regulations (you are calling "ECE rules") are in effect, either. UN R113 defines motorcycle headlamps, not car headlamps. R113 headlamps are permitted only on L-class vehicles (motorcycles). M- and N-class vehicles (cars and trucks) have to have headlamps as specified in UN R112 (halogen and LED), R98 (HID) and R123 (AFS/ADB) -- motorcycles may optionally be equipped with car/truck headlamps.

    Moreover, R113 (as well as R112) mentions lumens only with regard to certain light sources and combinations of light sources used in headlamps. R98 does not mention lumens at all. None of these regulations specify headlamp output in terms of lumens; there's not a word about lumens within the beam. Moreover, in all three regs the old lux specs at named screen-distance points were superseded years ago by candela specifications at angular coordinates.

    Cars going over crests is an issue but it's an annoyance, not so bad normally that you don't see anything. I've been blinded more by a too high aimed Edelux
    What you are doing here is very common and quite wrong: you are mistaking what you think you've seen/think you've felt for actual objective fact. We (humans) are not equipped to accurately judge how well our eyes are working, it only feels like we are. In terms of actual, measurable, objective visual performance you almost certainly haven't actually been "blinded" by an Edelux aimed too high, you just felt like you were.

    The issue is light emitting size... The smaller the lamp and thus emitting size, the more it will hinder, even blind you
    This is not correct. For any given intensity, a smaller emitting surface will naturally have higher luminance, which will mean looking at it causes more discomfort glare, but -- this is the important part -- increased luminance does not aggravate disability glare (i.e., the degradation of visual acuity). Disability glare is purely a function of intensity, not of luminance.

    similar to a laser
    Not at all similar to a laser. Lasers produce coherent beams; vehicle lights do not -- no matter what technology they incorporate.

    It might be a good idea for you to assume/guess less and learn/know more about the science of this field before you start handing out advice and trying to teach classes about it -- especially if you are trying to funnel business toward what appears to be some kind of commercial activity in consulting on vehicle lighting.

  12. #12

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by lumen aeternum View Post
    The US does not have the "euro style headlight" with the horizontal cutoff.
    This was true in the past, but most US low beams have had a cutoff at the top of the beam for about 20 years now. Compared to European practice there is more variation allowed in the shape of the cutoff under US regs, and as per market preferences the cutoff doesn't tend to be as sharp in US headlamps, but it is still a clearly defined cutoff line.

    Lots of upward spill
    This is a mix of outdated and incorrect information. Both US and UN ("European") regs prescribe minimum upward light from low beam, that is in the region 2 to 4 degrees above horizontal and 8 degrees left to 8 degrees right, to provide adequate light for retro-reflective road signs. The UN spec's minimum uplight requirement is somewhat greater (more light at minimum) than the US spec, but the US spec permits a great deal more light (more light at maximum) in this region than the UN spec. In practice, most US low beams provide adequate uplight without the "lots of upward spill" you mention.

    The US spec is much more stringent than the UN spec in controlling upward stray light (backscatter in foul weather), that is in the region from 10 to 90 degrees above horizontal.

    US aim specifications are higher; a low beam with a European type of cutoff shape is aimed 0.4° below horizontal, whereas in Europe the aim is at least 0.57° below horizontal (and goes down from there depending on lamp mount height). This seemingly minor difference is actually huge in terms of seeing distance.

    There is zero enforcement of headlight aiming or extra lighting being used.
    This is largely true, and it's a real problem.

    Apparant brightness is increased by using blue-er lights.
    This is the case all over the world; it's not unique to the US vicinity.

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    Moderator Alaric Darconville's Avatar
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Quote Originally Posted by swhs View Post
    Note that a lens is not a proper distributing optic!
    Oh, but it is.

    Have you not seen an automotive sealed beam headlamp? Many stop lamps? A great many turn signals? Very many examples of composite headlamps whose outer lenses perform optical functions?
    For example, the '95 Previa pictured here whose headlamps and auxiliary low beams use the outer lens as the final distributing optic:


    In the early '70s, there were experiments with reflector optics whose cover lens had no optical function. It first saw real production in the US market in 1990 (in Japan somewhat contemporaneously), and a few years later in Europe and the rest-of-world markets. This all was made possible by sufficiently-advanced reflector design and manufacture methods such that the reflector itself could do all the work and not need the lens to do the final light distribution. So to say a lens is not a proper distributing optic is to be misinformed. It's been a proper distributing optic for years and years and years and continues to be one to this day (take a look at the taillamp of this '20 Toyota Corolla here: https://cars.usnews.com/cars-trucks/...ior/tail-light). A lens is a proper distributing optic.

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    Flashaholic* Calina's Avatar
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    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    Think about lighthouse lamps. Their beam can be seen kilometers away, all shaped with lenses.
    Health is merely the slowest possible rate at which one can die.

  15. #15

    Default Re: Lupine Rotlicht LED Rear Light - 160 vs 40 Lm

    This claim that "If they don't see you with 40lm, they won't see you with 160lm either" is only technically correct or true if both the 40-lumen and the 160-lumen lamp fail to provide the intensity and luminance required for adequate conspicuity. The conspicuity of an object (literally, how conspicuous a thing is) is the ability of a person to quickly and accurately detect, identify and track that object. Many factors influence conspicuity. Lighting an object is one way of increasing its conspicuity. We discuss performance, perceptibility and conspicuity of lights and lamps, and glare produced by them, primarily in terms of illuminance (in lux) or intensity (in candela) and in terms of luminance (candela per square meter) because human observers of a light or lamp react in accordance with those quantities, which are only tangentially related to the flux produced by the light source ("source flux"), or the flux within the beam produced by the lamp ("road flux" or "beam flux"). At longer observation distances beyond 60 to 75 feet, intensity is the key to conspicuity and glare no matter whether it's a large low-luminance lit area or a small high-luminance lit area. At closer observation distances, under 60 to 75 feet, luminance is a co-relevant factor with intensity: higher luminance (such as by a relatively small lit area) means greater conspicuity and more glare.

    None of this is a guess or a pet idea; it's known science. This is an aspect of human vision that's been extensively studied over many years.

    The primary place for relevant discussion of flux lumens and beam lumens is in the engineering phase of a lamp. Discussion of lumens isn't quite irrelevant -- but almost -- in discussions of which lamp to buy, which lamp gives better functional and safety performance than some other lamp, etc.

    It's unfortunate that marketing and promotion of bicycle lamps is based so heavily on babbling about lumens; that is plain and simply the wrong thing to be focusing on. The same misleading distraction is used in the marketing of off-road motor vehicle lighting, and a variant of the same is used in the marketing of flashlights (often with candlepower instead of lumens). It's not the only area of lighting where it's easy for consumers to get irrelevant information and hard to access relevant information; that's the situation with LED household bulbs, too: lots of hype and noise about color temperature, but very little about color rendering, which is highly relevant to the functional and comfort quality of the light. It's not difficult to imagine why: many LED bulbs have poor color rendering, many bicycle lights have pathetic output in relevant intensity-distribution terms, and the relevant terms are more complex to explain and understand than the irrelevant ones.
    Last edited by -Virgil-; 02-16-2020 at 07:47 PM.

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