Cyclists who use strobe lights are...

[downfader]

I may be getting the wrong end of the stick here, but most modern led lamps strobe at something like 16-25Hz , it gives the illusion of a constant bright output but reduces the duty period of the led components saving battery life and extending the life of the led.

I think the waveform is the source for those hertz not the oscillation/amplitude of the on-off? I could be wrong.

 

[GrumpyGregry]

as a driver i have NEVER not been able to judge the distance or speed of a bike bcoz they had a front or rear flashing light. I think this is a bollox excuse from drivers who need an eye test. (that said, I'm yet to see a strobe light so I'll keep you posted)

I used to claim this until quiet recently. Learning otherwise was a sobering experience.

 

[the_mikey]

I think the waveform is the source for those hertz not the oscillation/amplitude of the on-off? I could be wrong.

Maybe the brightness is controlled by the width of the pulse, so a dim light has a low mark space ratio, and the brightness increases as the mark space ratio increases.

 

[fossyant]

Maybe the brightness is controlled by the width of the pulse, so a dim light has a low mark space ratio, and the brightness increases as the mark space ratio increases.

Sorry but that's just talking rubbish.

The flash rate is too high on many of these lights.

 

[gaz]

I run a 350 lumen rear light on the back of my low racer & it's not objectionable in the least, intact I probably need to drive it a little harder because at close range it can look a bit dim! The reason? It has a surface area of 122.71cm^2, a typical rear back light will have a surface area of 2.54mm^2. If we do the maths that gives my rear light 2.85 lumen 1cm^2 but if you take a 75lumen 1 LED rear you're looking at 30 lumen per 1cm^2! That's car rear HID/brake light range.

That intensity of the less bright light means your eye tones down so that the point source isn't overloading its sensing abilities. That makes it very hard to see anything else. However my brighter rear light simply doesn't get that intense, it actually seems to get dimmer the closer you are to it!

The problem with making something that big is that on a conventional bike it's kind of hard to mount a 13.25cm diameter light.

350lumen rear light? What is it :S

 

[classic33]

I was about to say that the Epilepsy thing is more complex

It is about a whole range of factors - the only "recorded" incident was where the person was fettling and it may be the intensity at close range rather than the flashing rate that was the cause

I was a welder at one time, and it never triggerered a seizure.
When we get passed the blinkered view that flashing lights can trigger a siezure then we can knock this myth on it head, once and for all.

 

[Black Country Ste]

I caught this in December. Never intended as a bike light. Wish I'd said something.

[edited]

 

[classic33]

I caught this in December. Ridiculously focussed beam, illegal flash frequency and could cause epileptic reactions in those affected. Wish I'd said something.

As could all the headlights coming the over way, one after the other, using that reasoning. Theres the same strobe effect there and the lights are brighter.
See
http://www.epilepsysociety.org.uk/photosensitive-epilepsy & https://www.epilepsy.org.uk/info/photosensitive-epilepsy/triggers
I mean can we get rid of these, using the same argument.

The hardest part with living with the bloody thing is peoples preconceptions of the condition. And what may cause the bloody seizure in the first place!
We are not blinking stupid about a condition we suffer from.

 

[Black Country Ste]

Fair enough. But you don't disagree that lights like that are a dangerous nuisance?

 

[classic33]

Fair enough. But you don't disagree that lights like that are a dangerous nuisance?

Bright headlights on cars in a line of stationary traffic can be just as bad when you're travelling the other way. And the strobe effect is there as well.

 

[classic33]

Health & Safety gone mad is a better way of describing it.
Unless you're well lit up, lights that can be seen for miles have become a basic for anyone buying new lights. And the sad fact is people fall for it.
I have a horse riders vest, LED's built into it. Does it get me noticed at night? I don't think it has once been noticed whilst actually moving on the bike. At a set of lights with a car in the next lane, yes.
I fitted a half million candle power light to the bike when working in Leeds, using it on the unlit sections of the A58, I still got the excuse that my front light wasn't bright enough when I got knocked off by a British Gas van driver. Police disagreed, when one of them went to check it.

 

[ufkacbln]

I caught this in December. Ridiculously focussed beam, illegal flash frequency and could cause epileptic reactions in those affected. Wish I'd said something.

Difficult to measure the flashing rate, but see above, it is very unlikely to cause an epileptic fit.

According to the British Epilepsy Association there are no recorded cases where a bicycle light has triggered an epileptic fit

 

[GrasB]

350lumen rear light? What is it :S

Grasb ltd. I-can't-find-the-light-I-want-so-I-made-my-own model
I started off with this 12 LED Osram module which was too intense & ended up getting someone to make up a very similar PCB with lower power LEDs on it.

 

[wiggydiggy]

Difficult to measure the flashing rate, but see above, it is very unlikely to cause an epileptic fit.

According to the British Epilepsy Association there are no recorded cases where a bicycle light has triggered an epileptic fit

Out of interest, how do you measure a lights flash speed?

Tried a couple apps online but they are making a strobe, not measuring.

Thinking something using the camera fucntion on my phone?

 

[Black Country Ste]

To save myself a lynching I've edited out the nonsense. Forgive my ignorance.