Govt to limit power of cycle lights ?

Tonyf33
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Re: Govt to limit power of cycle lights ?

Postby Tonyf33 » 7 Apr 2013, 4:18pm

much of the problem is cost, who could or want to pay out £100+ for the types of lights that seem to fit the bill that has been talked about withthe right pattern and cut off as well as being bright enough. Many dynamo light systems are very expensive (by comparison to many lights that are battery driven) and all but the very serious cyclist wouldn't outlay nor would want them.
I also don't think we should be making direct comparison between car headlights & bikes. A bicycle is so much more vulnerable to the fluctuations in the road whereas a motor vehicle is not due to 4 wide tyres with shock absorbing properties at each corner. So the actual amount of light required to define the road surface as much as a cyclist would want is not the same for a motorvehicle.
For example, down the unlit back road(6% downhill) that I know where all the bumps are I could easily drive the car on side/parking lamps alone at 25-30mph, there's no way would i be able to do half that speed with that amount of light on a bike.

TonyR
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Re: Govt to limit power of cycle lights ?

Postby TonyR » 7 Apr 2013, 4:28pm

Nettled Shin wrote:
TonyR wrote:Much of the advance in LED brightness has been from getting the heat out of the chip better which means attaching it to a good thermal mass and radiator.
Thermal mass isn't going to affect the steady-state temperature, is it.


It is with a good conduction path with low thermal impedance which also involves short large cross section high thermal conductivity materials

Like how the secondary mirror gets in the way in a Newtonian telescope?


You don't need to get heat out of the secondary mirror so it can be quite small with thin mounting struts and yes is does occlude the light and reduce the light collection efficiency.

Yes, on second thoughts, look how effective a design mounting the LED rearward is; any heatsink can be directly exposed to airflow, keeping the sink smaller or cooler through forced convection cooling---ideally complemented by dynamo power!


That depends on a) reasonable forward motion and b) not too high ambient temperatures neither of which can be guaranteed.

TBH, the LED could be mounted in the side of the lamp housing if heat rejection and light obscuration is a real issue for you. My major point was that our being able to see the tiny radiating LED surface directly is what makes them so uncomfortable for us to look at. O&O.


Yes they can but it makes the optics more complex. Some good lamps do that, most of the cheap ones stick the emitter facing forwards in the centre

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Re: Govt to limit power of cycle lights ?

Postby TonyR » 7 Apr 2013, 4:36pm

squeaker wrote:
SA_SA_SA wrote:Presumably the legal C&U light measurement kit has some sort of spectral weighting function? IMO it needs tweaking to emphasise the blue end of the spectrum more.


The use of candelas involves a spectral weighting function for the sensitivity of the human eye but that is based on day, not night, vision (photopic not scotopic if you want to read it up). Night vision is much more sensitive in the blue and less in the red.

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CJ
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Re: Govt to limit power of cycle lights ?

Postby CJ » 8 Apr 2013, 10:30am

TonyR wrote:The use of candelas involves a spectral weighting function for the sensitivity of the human eye but that is based on day, not night, vision (photopic not scotopic if you want to read it up). Night vision is much more sensitive in the blue and less in the red.

Thanks for saving me the trouble of pointing that out. And it's not just candelas, ALL the units used for measuring visible light are based on how eyes work in daylight. By skewing their products toward the blue, the manufacturers provide a more effective light than is indicated by the number of candela, lux or lumens. As well as more effective it will of course be more dazzling, but to make it more yellow is poor engineering when what's obviously needed is a different scale of measurement: i.e. scotopic lumens and candela. I hear that the world of lighting standards is working on such a solution (actually mezopic, to embody the mixture of modes, partly photopic and partly scotopic, in which the eye operates when using a lamp in the dark).
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SA_SA_SA
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Re: Govt to limit power of cycle lights ?

Postby SA_SA_SA » 8 Apr 2013, 2:10pm

I seem to have the knack of getting the last post on a page, so some points get missed :(

( http://forum.ctc.org.uk/viewtopic.php?f=6&t=74339&start=30#p650425)

However, for the above above point on this page
CJ wrote:ALL the units used for measuring visible light are based on how eyes work in daylight. By skewing their products toward the blue, ....As well as more effective it will of course be more dazzling, but to make it more yellow is poor engineering .... I hear that the world of lighting standards is working on such a solution (actually mezopic, to embody the mixture of modes, partly photopic and partly scotopic, in which the eye operates when using a lamp in the dark).


I knew that light measurement was "eye-weighted" but not about the proposed night weighting.
I have read that blue is more dazzling because it does not operate pupil contraction like other colours, and that some people may possibly be especially sensitive to the blue in HID lamps apart from that feature (hence an special dislike of HID lamps).

By "poor engineering" do you mean blue light is better for being seen (more bang per photon), rather than seeing the road (especially when wet) which is what I was concerned about.
For powerful lamps I would prefer less blue light to avoid unnecessary glare discomfort to others, and for better colour contrast on the road, especially wet roads: eg grass verges are green not blue. Also, bluer white light seems to often be reported as poorer in rain/ wet roads: my old LED DLumitec isn't very good at all in the rain, but OK in the dry.

I am afraid I don't like very blue-white car headlamps and as bike lamps become brighter I would like these to be less blue too.

http://www.danielsternlighting.com/tech ... d/bad.html
http://www.danielsternlighting.com/tech ... color.html
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CJ
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Re: Govt to limit power of cycle lights ?

Postby CJ » 8 Apr 2013, 2:41pm

SA_SA_SA wrote:By "poor engineering" do you mean blue light is better for being seen (more bang per photon), rather than seeing the road (especially when wet) which is what I was concerned about.

I'd have thought it should be better for both, most of the time (except in fog perhaps), and that colour of light is very much a secondary matter compared to its intensity - except in so far as it results in a discrepancy between measured and subjective intensity.

When it comes to being seen, it nevertheless occurs to me that since cones (that see in colour but need more light to work at all) are concentrated in the centre of the retina, leaving peripheral vision to the rods, that see in b&w but are nevertheless more sensitive to the blue-green part of the spectrum: a bluish light should be particularly good for attracting the attention of a driver who is looking elsewhere - like they so often are.

I reckon life-saving attention-grabbing and distressing glare are two sides of the same coin. You can't do one without hazarding the other. Best you can do is set a level for one that seems effective enough without causing too much of the other.

And whoever chose red for stop and green for go? What a rubbish decision that was!
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[XAP]Bob
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Re: Govt to limit power of cycle lights ?

Postby [XAP]Bob » 8 Apr 2013, 4:53pm

CJ wrote:And whoever chose red for stop and green for go? What a rubbish decision that was!


How many people are RG colour blind? Quite a lot - although we have two mitigating factors.

One is that we also have a consistent orientation for lights, so bottom light is go, middle light is floor it and top light is "OK if it's just turned on".

The other is that despite RG colour blindness alot of people can tell the difference through tone - not all though.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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Re: Govt to limit power of cycle lights ?

Postby SA_SA_SA » 8 Apr 2013, 5:13pm

CJ wrote:"SA_SA_SA wrote:.....do you mean blue light is better for""
I'd have thought it should be better for both, ....


The Daniel Stern person seemed to think otherwise (I have ignored the bits about Blue filtered cold white halogen lamps being worse than normal halogens as obviously not applicable to LEDs).

It would be nice if most cycle lamps like the Cyo came with a choice of neutral white or the usual cold white.

CJ wrote:When it comes to being seen,...a bluish light should be particularly good for attracting the attention of a driver who is looking elsewhere. I reckon life-saving attention-grabbing and distressing glare are two sides of the same coin. You can't do one without hazarding the other. Best you can do is set a level for one that seems effective enough without causing too much of the other.

It would then be better if such lamps were not permitted to cars etc and limited in brightness more than other shades.
Perhaps separating the low power blue white attention-grabbing lamp function from the high power warmer white seeing lamp function would minimise dazzle whilst catching attention.


CJ wrote:And whoever chose red for stop and green for go? What a rubbish decision that was!

I don't mind but in a parallel world....
http://sliders.wikia.com/wiki/Elvis_World :)

NB XapBob: I think Green traffic lights are blueish green to help colour blind persons.
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Re: Govt to limit power of cycle lights ?

Postby MikeF » 17 Apr 2013, 11:55pm

[XAP]Bob wrote:
CJ wrote:And whoever chose red for stop and green for go? What a rubbish decision that was!


How many people are RG colour blind? Quite a lot - although we have two mitigating factors.

One is that we also have a consistent orientation for lights, so bottom light is go, middle light is floor it and top light is "OK if it's just turned on".

The other is that despite RG colour blindness alot of people can tell the difference through tone - not all though.

Strictly bottom light/"go" means proceed IF IT SAFE TO DO SO, but then I can remember when the red also also displayed (in black) the word "STOP", supposedly to avoid any doubt.
As I don't think I'm colour blind I don't know how others, who might be, saw it. :wink:
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Re: Govt to limit power of cycle lights ?

Postby fullupandslowingdown » 2 Jun 2013, 4:06am

seems to me that the police have been falling asleep over motor vehicle lights for the last couple of years. I'm certain there is a specific law (construction and use regs) that prohibits the use of any light which is not either white/clear, amber or yellow, or red on a motor vehicel, except for the illuminated sign which has to be placed within a certain area above a lorryor coach cab. But the number of cars, and lorries now that have blue lights (and no, they're not ice blue or bluish white but actually blue I'm talking about) fitted to their wheels, under their bonnets, on the radiators etc, is esculating. The law was for a good reason, i.e. avoid confusion with traffic lights, or emergency services blue lights. Likewise after market exhausts aren't legal if they allow more noise to escape than the manufacturers pattern part. But you can hear some cars literally half a mile away. So is the police gonna clamp down on all these lawbreakers as well as naughty cyclists.

I do admit that some bike lights seem way too bright, but thats more a lens design fault than the actual total quantity of light. I know I want a broader spread of light rather than the bare meter width that most give so I can see obstacles to either side which if I had to swerve for some other reason, I would know about before it was too late. And also on those really silly twisty cycle lanes, it's nice to know where you are about to turn to. Have many modern bike light manufacturers actually started off as torch makers who use a basic lens giving a circular spread of light. And we just been cyclists, they don't bother to make better lenses that actually give the right spread. I don't like flashing front lights either, though thats personal.

Further more I suspect that at MOTs testers aren't always ensuring that the beam adjustment for load is set at minimum before checking the headlight adjustment, as no end of cars now seem to have lights that are set too high. Unless my intelligence is failing me, it seems that a beam load adjuster should never be able to raise the beam higher than the correct level, as the load in a car will always be no further forward than the front seats, and often in the back, hence the adjustment needed is always downwards, and anyway almost all cars already have a heavy lump at the front. So unless all these cars are going around with substantial loads all the time in the boot, and they don't appear to be, the alignment is off to start with.

The regulations for testing motor vehicle lights at an MOT are ineffective anyway. The output is tested at the same height of the light on the vehicle, so for a big 4x4 it's beam is considered legal even though it is higher than say a small sports car. Thats why you will always get more dazzle from a rangerover than a lambourgini.

And why oh why did the government ever allow some of these rubbish indicators to be approved. The ones that are barely visible in daylight, you have to be in the right place to see them, and especially so when the headlight is on too. Indicators should be located at or very near the edge of the vehicle where they always were, not almost halfway across the radiator. I'm suprised there aren't more accidents due to others not seeing them. Not that some drivers even bother indicating to turn, so perhaps we also need the australian law brought in. Indicate or be fined, regardless.

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Re: Govt to limit power of cycle lights ?

Postby SA_SA_SA » 17 Jun 2013, 5:21pm

On further observation, projector headlamps don't seem to be necessarily more dazzling than the "best"* dipped lamps (although some are).
As they were presumably developed to replace popup headlamps on sports cars I wonder what the point of fitting them to ordinary cars is (other than fashion)?

*best as in least dazzling


fullupandslowingdown wrote: allowed rubbish indicators to be approved. The ones that are barely visible in daylight,

+1
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[XAP]Bob
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Re: Govt to limit power of cycle lights ?

Postby [XAP]Bob » 3 Nov 2013, 7:56pm

And in any situation where the ambient light level is good enough that you can't easily see where your headlamp is pointed and don't need it enough to bother improving its aim, you won't be dazzling anyone anyway, because glare only happens against a much darker background.

With Audi's DLRs I have to disagree - maybe dazzle is the wrong word, but I find them painfully bright, even in daylight. Maybe a bright summers day would allow my eyes to moderate the light effectively, but they are just evil.
I find that when driving a scenic as well as when on the 'bent.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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Re: Govt to limit power of cycle lights ?

Postby MikeF » 4 Nov 2013, 8:23pm

Nettled Shin wrote:... by preventing the emitter surface from being directly visible, and using larger reflectors, things could be made more tolerable, without needing to reduce the intensity of road illumination.
I think this is a most significant point. Cycle lights where the emitter is directly visible can be the most dazzling.
I've just bought a Luxos B and I'm very impressed with the beam pattern and brightness. It's possible to align it so that the beam will light up a facing car number plate at say 20metres, but not shine on the bonnet or steering wheel. It gives a broadly U shaped beam with a very sharp cut off as well as sending out light to the side for side visibility. The LED is not directly visible unless you are at ground level looking at the lamp. The only thing I can't assess is how it looks from an oncoming driver's viewpoint. A problem all cyclists face. :wink: I have also a new Cyo and am thinking about using it as a switchable high beam - even though that has a sharp cut off.
[XAP]Bob wrote:
And in any situation where the ambient light level is good enough that you can't easily see where your headlamp is pointed and don't need it enough to bother improving its aim, you won't be dazzling anyone anyway, because glare only happens against a much darker background.

With Audi's DLRs I have to disagree - maybe dazzle is the wrong word, but I find them painfully bright, even in daylight. Maybe a bright summers day would allow my eyes to moderate the light effectively, but they are just evil.
I find that when driving a scenic as well as when on the 'bent.
Couldn't agree more. It's not just Audis either. In fact in the dark on unlit roads DLRs are nearly as good as dipped headlights; a friend of mine started driving off the other day without realising no others lights were on.
fullupandslowingdown wrote:And why oh why did the government ever allow some of these rubbish indicators to be approved. The ones that are barely visible in daylight, you have to be in the right place to see them, and especially so when the headlight is on too. Indicators should be located at or very near the edge of the vehicle where they always were, not almost halfway across the radiator.
The reason they were moved away from the headlight is so they weren't outshone by it. My mother used to complain when semaphore indicators were changed to the modern flashing ones as it needed two places to look. :lol:

If only lights of a certain standard (whatever that might be) could be sold, then that would, partially at least, reduce the plethora of unsatisfactory lights. Some of the onus of implementation would then fall on trading standards officers rather than just the police.
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Re: Govt to limit power of cycle lights ?

Postby MikeF » 4 Nov 2013, 8:33pm

SA_SA_SA wrote:On further observation, projector headlamps don't seem to be necessarily more dazzling than the "best"* dipped lamps (although some are).
As they were presumably developed to replace popup headlamps on sports cars I wonder what the point of fitting them to ordinary cars is (other than fashion)?

*best as in least dazzling


MikeF wrote: allowed rubbish indicators to be approved. The ones that are barely visible in daylight,

+1
I didn't write that :!:
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Re: Govt to limit power of cycle lights ?

Postby SA_SA_SA » 4 Nov 2013, 9:22pm

MikeF wrote:I didn't write that :!:


Oops: I have now corrected it.
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