Front Light for daytime

Commuting, Day rides, Audax, Incidents, etc.
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mjr
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Re: Front Light for daytime

Post by mjr »

[XAP]Bob wrote:
mjr wrote:
hemo wrote:The fact that they have several light modes dosen't mean you have to use the high setting, outer bezzle strobe is the one I use most.

If that's an actual strobe, it's illegal and anti-social. Please stop it. Flash between 1 and 4 times a second if you have any dignity.



Why is 1-4Hz not a strobe?

Even 4Hz is too slow to trigger stroboscopic effects in most people, especially if the on and off phases are balanced. Especially important is that there are no reliable reproducible cases of triggering seizures at that rate.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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[XAP]Bob
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Re: Front Light for daytime

Post by [XAP]Bob »

So you mean isn't an epilepsy inducing frequency rather than 'isn't a strobe'.

A true strobe light can go much slower than that if needed...

RVLR requires between 2 and 4 Hz with an even 50% duty cycle. (From memory)
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.
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mjr
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Re: Front Light for daytime

Post by mjr »

If it's got a 50% duty cycle at those frequencies, it's not a strobe, is it?
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hemo
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Re: Front Light for daytime

Post by hemo »

As long as I have a light on the bike not really bothered about what it does and doesn't do, better then having none which if often the case esp at night.
Ric2013
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Re: Front Light for daytime

Post by Ric2013 »

I take the attitude that if you don't know how to adjust the headlight height on a vehicle with adjustable height headlights ('no, don't help me find the switch, I'll take it to the mechanic soon'), then you shouldn't be driving it at night any more than someone who doesn't know how to use the wiper controls on a car should be driving it in the rain - or at all.

But where is the policeman pulling people over? Either in an office somewhere, or else he retired and wasn't replaced. But it keeps taxes down so that's good. (?)
Cyril Haearn
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Re: Front Light for daytime

Post by Cyril Haearn »

Working for the police is like travelling in a Rolls-Royce

In a Rolls the loudest sound is the ticking of the clock

In police HQ the loudest sound is the clicking of the mice
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21pavone
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Re: Front Light for daytime

Post by 21pavone »

fatbelly33 wrote:Hi All,
Just got back into Cycling & I'm loving it. All of my Cycling is done during daylight hours & I'm looking for a bright front light to alert Car drivers that I'm there. Can anyone recommend a bright front light (LED perhaps). I've seen the flashing ones & they get my attention whilst I'm in the Car so was thinking flashing is the way to go. I am on a budget & would prefer to pay less than £35.

Thanks.


Lezyne Zecto Drive 250. Can be bought for around £20/25. Small enough to fit on your bars or around brake/gear cables, not blindingly bright, lasts ages on flashing.


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels
busb
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Re: Front Light for daytime

Post by busb »

[XAP]Bob wrote:Frankly I'd rather see tighter restrictions on motor vehicle headlamps to start with. They are generally horribly bright and dazzling... That is even from my driving position high up in an MPV.

The adjustment of beam angle needs to be a lot tighter, and needs to be automatic - the number of people who have their 'dipped beam' set well above the horizon is absurd.


In theory at least, I thought all motor vehicles should be checked once a year that includes headlight adjustment during an MOT - is this not the case? It's not really feasible to do do this with cycles! Motor vehicle's headlights do have shaped beam patterns in dip mode unlike most cycle lights that appear to have a wide & uniformly angular pattern. Although I tend to point my lights to illuminate their brightest patch about 10 or so feet in front, if on flash mode, I can clearly see reflective signs well above me flash in sync - probably up to 20 feet up or so.

Most lamp's intensity is measured in lumens using an integrating sphere that measures the average illumination in all directions - my understanding is this method is used to measure all sorts of sources from fluorescent tubes, incandescent bulbs, LEDs etc. This will give an average figure. Headlight testing will include angular intensity polar diagrams utilising an optical goniometer. My understanding of Lumens as a measurement is an absolute figure that effectively discounts distance. The other major unit of intensity is the Lux that is measured at a defined distance from the source. Lux measurements read the incidental light falling on a sensor. The closer the distance, the higher the Lux reading where for a point source, will drop with the square of the distance such as a bare household light bulb. Take a reading of a collimated beam such as a laser & the Lux reading will be fairly uniform v distance. Measurements get challenging when trying to evaluate glare (dazzle). This is a far more subjective measurement that attempts to to contrast the average background intensity v point sources giving a ratio. Our interest will be biased towards nighttime glare from headlights but the method is also used for workplace lighting or daylight where the sun's intensity v ambient lighting needs to be measured. The method seems to require a wide-angle camera mapping intensity as false colours & fairly sophisticated software. My suspicion is that glare measurements are neither easy nor commonly undertaken. One point very relevant to road-users is that the smaller the headlight's area, the higher the potential glare will be though the Lumen figure might well be the same. Shrinking the headlight will therefore increase glare. The older we get, the more prone we get. My knowledge of the subject isn't definitive but too much emphasis is given to average intensity measurements & not enough to peak intensity, IMHO. If you read up on glare, you will encounter terms such discomfort glare & disability glare which are rather subjective terms.
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Re: Front Light for daytime

Post by Samuel D »

busb wrote:In theory at least, I thought all motor vehicles should be checked once a year that includes headlight adjustment during an MOT - is this not the case?

When a car is loaded – luggage in the boot, passengers, or even a full tank of fuel in some cases – its attitude changes. Therefore the headlamps need to be adjusted almost every time the car is used. For this purpose an adjustment was provided on the dashboard, albeit often hidden away by the driver’s knee as if the makers suspected it would not often be used.

You only have to drive down the road to see that the manufacturers’ suspicion was justified.

With new headlamps that have greater dazzling risk (brighter, smaller, sharper cut-off, bluer, holes in the spectral power distribution) the EU mandated automatic adjustment of headlamp angle as the car’s load changes. Most new cars have this plainly necessary feature. (To make up for this, they have DRLs that dazzle even in daylight and allow dozy drivers to drive at night with DRLs instead of dipped headlamps.)

Bicycles are a law unto themselves and the lighting situation there is out of control. The law is a mess in most European countries and what bits and pieces of disjointed legislation exist are either daft or not enforced.

Road safety has improved greatly for other reasons, and that may be why lighting has not been given the attention it deserves for both safety and comfort reasons. Eventually that must change.
Cyril Haearn
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Re: Front Light for daytime

Post by Cyril Haearn »

When cycling I am afraid I find lights on moving motors good, the town is full of vehicles and one can identify moving ones easier

When driving I do not use lights in daylight, but I do in the midday gloaming
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[XAP]Bob
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Re: Front Light for daytime

Post by [XAP]Bob »

mjr wrote:If it's got a 50% duty cycle at those frequencies, it's not a strobe, is it?

It's not a variable one certainly...
...but a decent strobe has both interval and duration configurable, so you could have a 50% cycle.
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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