Rear LED light effectiveness.



Alistair Gunn wrote:
> [email protected] twisted the electrons to say:
> > As I overtook him I saw it was a Cateye LD600 on the chasing mode where
> > each LED lights up in turn but there is only one LED on at any time.
>
> Was it mounted horizontally or vertically?

It was mounted vertically. I think the battery may have been low as
well but as I said I was surprised by the fact the chasing movement
wasn't apparent until I was very close to the bike.
For what its worth and this is totally unscientific the most
visible rear setip I've ever seen was triple LD600s all in full
flashing mode. The bike I saw had them mounted on the left and right
edges of the rear rack and on the seat tube. As the lights were
flashing at slightly different times it gave a chasing effect but over
the width of the bike hence the chase effect was visible from a
distance unlike the single LD600 I saw.

Iain
 
Iain

Let me get this right.

From 100m away you saw the light.

How fast does one have to go in order that 100m visibility of a cyclists
rear light is not sufficient warning. If he had been a pedestrian he would
not have had any rear light.

Far from being useless it seemed to be very effective.

Were you looking for a higher degree of visibility than was reasonable?

What would you have done if his light had been brighter?

Would you have driven any differently?

Best regards

Rod King

<[email protected]> wrote in message
news:[email protected]...
> Driving home last night I overtook a cyclist with what from about 100m
> away I thought was a very dim constant rear light. As I overtook him I
> saw it was a Cateye LD600 on the chasing mode where each LED lights up
> in turn but there is only one LED on at any time. So from the
> perspective of a driver this mode would appear to be useless. IE only 1
> fifth of the light put out compared to either the constant mode where
> all LEDs are lit or the flashing mode where all LEDs flash
> simultaneously. Plus from a distance the chasing mode loses the
> flashing effect.
> I use two LD600s on my commuter but don't use the chasing mode anyway.
> But it made me wonder whether anyone knew of any side by side
> comparisons of LED lights. Given sites like "Your Tube" and Google
> Video it would be possible to post video clips of different lights "in
> action" so to speak, perhaps side by side comparisons.
> As a side issue the cyclist concerned had a poor rear light, no
> reflectors and dark clothing. But he was wearing a helmet so
> everything would be OK right?
>
> Iain
>
 
Zog The Undeniable wrote:

> LEDs are also generally awful when run from NiMH cells. The slightly
> lower voltage gives *half* the brightness (I measured it with a light
> meter).

The LED lights I use look OK on NiMHs, including Smart Polaris. To be
fair, you should compare with half used alkaines, not brand new ones.
Even with relatively low drain devices like LED lights, alkaline cell
voltage drops below 1.2V before the average reasonably responsible cyclist
throws them away (and the average pob goes on using them until they're
dead).

~PB
 
On 14 Mar 2006, [email protected] <[email protected]> wrote:
>
> Ian Smith wrote:
> >
> > I agree. I've seen research that says chasing lights are particlarly
> > effective.
>
> What research?

I have no citation to hand. The gist of it was that movement attracts
attention, and that moving lights (or lights which appear to move) are
better than flashing lights at attracting attention. However, it
presupposes that you can arrange lights that appear to move, which is
difficult, while it's easy to arrange lights that appear to flash.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|
 
On Tue, 14 Mar, Pete Biggs <> wrote:
> Peter Fox wrote:
>
> > Actually when 'all LEDs are on' they are switched. In the dark wave
> > the light in front of you and you won't see a constant blur. (But
> > that's not very relevant to the discussion.)
>
> Is that the case with every cycle LED light on the market? LEDs don't
> /have/ to be pulsed. They can just be used like light bulbs with a
> constant current.

No, it is not. I have had some that flash at high frequency, and some
that do not (at least, at a frequency that teh 'wave it in front of
your face' test detects - I've not put every light I possess on an
oscilloscope).

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|
 
<[email protected]> wrote in message
news:[email protected]...
> Driving home last night I overtook a cyclist with what from about 100m
> away I thought was a very dim constant rear light. As I overtook him I
> saw it was a Cateye LD600 on the chasing mode where each LED lights up
> in turn but there is only one LED on at any time. So from the
> perspective of a driver this mode would appear to be useless. IE only 1
> fifth of the light put out compared to either the constant mode where
> all LEDs are lit or the flashing mode where all LEDs flash
> simultaneously. Plus from a distance the chasing mode loses the
> flashing effect.
> I use two LD600s on my commuter but don't use the chasing mode anyway.
> But it made me wonder whether anyone knew of any side by side
> comparisons of LED lights. Given sites like "Your Tube" and Google
> Video it would be possible to post video clips of different lights "in
> action" so to speak, perhaps side by side comparisons.
> As a side issue the cyclist concerned had a poor rear light, no
> reflectors and dark clothing. But he was wearing a helmet so
> everything would be OK right?
>


I've been horrified by dim cyclists whilst driving as well.

At night I wear a yellow hi-vis altura coat.
I use a 2002 Halfords LED rear on continuous, it has a large surface area
and can be seen from afar.
I put new batteries in it before it gets dim. 1 pint = 2 sets of super duper
batteries.

Stealth cycling needs to end.

John
 
[email protected] wrote:
> For what its worth and this is totally unscientific the most
> visible rear setip I've ever seen was triple LD600s all in full
> flashing mode. The bike I saw had them mounted on the left and right
> edges of the rear rack and on the seat tube. As the lights were
> flashing at slightly different times it gave a chasing effect but over
> the width of the bike hence the chase effect was visible from a
> distance unlike the single LD600 I saw.

A chap I often ride some of the way home with wires up his rear lights
to run from a battery in a lunchbox mounted to the top of his rack. His
current setup has one steady lamp on the back of the rack, plus 3 small,
round flashing mudguard lights arranged in an inverted 'V', with one
above the rack and one on either side of the rack, about a pannier's
width out. Those 3 flashing lights are very visible from a distance.
The fact that they all flash at slightly different rates seems to make
them stand out even more. And even without the steady light, gauging
distance isn't too difficult because at any time at least one of the
flashing lights will usually be lit.

I'm not generally a fan of flashing lights, but this is an exception.

--
Danny Colyer <URL:http://www.colyer.plus.com/danny/>
Subscribe to PlusNet <URL:http://www.colyer.plus.com/referral/>
"He who dares not offend cannot be honest." - Thomas Paine
 

>
> I've been horrified by dim cyclists whilst driving as well.
>
Why were you horrified?

At what distance did you see the cyclists?

Did it really effect the safety or was it just that you realised the light
could have been brighter?

If you had been able to see the cyclist from a great distance, would it have
mattered?


I'm interested!!!!



> At night I wear a yellow hi-vis altura coat.
> I use a 2002 Halfords LED rear on continuous, it has a large surface area
> and can be seen from afar.
> I put new batteries in it before it gets dim. 1 pint = 2 sets of super
duper
> batteries.
>
> Stealth cycling needs to end.

Yes but does dressing up like a Chritmase tree need to begin?

Rod

>
> John
>
>
 
Zog The Undeniable wrote:

> LEDs are also generally awful when run from NiMH cells.

"Nickel Metal-Hydride batteries have a high capacity and a very flat
discharge curve which maintains a cell voltage of 1.2V over ~80% of the
discharge curve. This gives a nominal pack voltage of 4.8V which as you
can see from the graph brings the mean efficiency up toward 70% and since
the fully charged voltage of the pack is only 5.6V the maximum LED power
is about 1.3W for a brief period and stays at 1W for most of the discharge
cycle. If you do not want to modify the light I strongly recommend you use
NiMH rechargeable batteries, you will get much longer run times."
- http://www.ajjrice.plus.com/reviews/smart nova.htm

~PB
 
In article <[email protected]>,
[email protected] (Eatmorepies) wrote:

> I've been horrified by dim cyclists whilst driving as well.

I was horrified by the bloke cycling without lights in London the other
night while carrying his young daughter on the crossbar. It was a cold
night as well and the poor kid had no gloves.
 
Terry wrote:
>
> I was horrified by the bloke cycling without lights in London the other
> night while carrying his young daughter on the crossbar. It was a cold
> night as well and the poor kid had no gloves.
>

Although I use lights in London to be honest they are not critical
unless it is raining. Street lighting is very good and visibility of
cyclists is not a problem in general.

--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham
 
In article <[email protected]>, [email protected] (Tony
Raven) wrote:

> Terry wrote:
> >
> > I was horrified by the bloke cycling without lights in London the
> > other night while carrying his young daughter on the crossbar. It was
> > a cold night as well and the poor kid had no gloves.
> >
>
> Although I use lights in London to be honest they are not critical
> unless it is raining. Street lighting is very good and visibility of
> cyclists is not a problem in general.

Ah, so you know the street I'm referring to, and are thus aware that it is
a narrow rat-run with poor lighting, road-humps, cars parked on both
sides, and cars entering and crossing having limited visibility due to
parked cars?

I'm so very glad that neither you nor the **** risking his kid's life is
my dad.
 
Rod King wrote:
> Iain
>
> Let me get this right.
>
> From 100m away you saw the light.
>
> How fast does one have to go in order that 100m visibility of a cyclists
> rear light is not sufficient warning. If he had been a pedestrian he would
> not have had any rear light.
>
> Far from being useless it seemed to be very effective.
>
> Were you looking for a higher degree of visibility than was reasonable?
>
> What would you have done if his light had been brighter?
>
> Would you have driven any differently?

Rod
In answer to your questions. The street concerned was a well lit
urban street. At the point I overtook it was a 30mph limit although it
changed to a 50mph limit a couple of hundred metres later. I wouldn't
describe his light as being effective as I saw the cyclist (despite
dark non reflective clothing) before I saw the light.
I wasn't looking for any degree of visibility. If an unlit
pedestrian (a drunk perhaps) had been lying in the road I would have
seen him in plenty of time and taken the appropriate action.
What I would have done if his light had been brighter is I would
have seen him earlier.
I woud have driven differently by moving into the outside lane
earlier.
The vast majority of drivers will see cyclists whether lit or not
early enough to miss them. But I believe that being very visible might
save my life one night when that 1 in 100,000, or whatever, driver who
is drunk, using a mobile, with poor eyesight, or careless sees me a few
seconds earlier than he or she otherwise might.
With regard to pedestrians being seen there was a pedestrian
killed a few years ago 2 miles from where I live. He was walking along
an unlit road with no pavement and was killed by a taxi (driver sober)
who didn't see him in time. If that ped had been wearing bright
clothing he might be alive who knows. The accident as far as I'm
concerned was 100% the drivers fault but that doesn't make the ped any
less dead.
Given that it costs next to nothing (in either cash or hassle) to
be well lit I see no argument for not running at least 2 rear lights.
But it's a free country and its an individual choice. Long may it
remain so.
 
<[email protected]> wrote in message
news:[email protected]...

> Given that it costs next to nothing (in either cash or hassle) to
> be well lit I see no argument for not running at least 2 rear lights.

It's cash and hassle - primarily the latter. Our bikes have lights which are
ready to use all the time, and have no need of charging or worries about
batteries going flat. The back lights don't use bulbs, and will work even if
the front bulb has blown. They're permanently attached, so no need to take
them off when parking.

I see no need for having any more than the one rear light per bike they
currently have.

cheers,
clive
 
Tony Raven wrote:
> Terry wrote:
>
>>
>> I was horrified by the bloke cycling without lights in London the
>> other night while carrying his young daughter on the crossbar. It was
>> a cold night as well and the poor kid had no gloves.
>>
>
> Although I use lights in London to be honest they are not critical
> unless it is raining. Street lighting is very good and visibility of
> cyclists is not a problem in general.
>

Generally I would agree - similarly, in most of urban London car drivers
can probably get away without lights after dark, too - at least in terms
of lights as aids to seeing.

But lights - any lights - really do aid you *being* seen. Bright is
better than dim, but some is a lot better than none.
 
Pete Biggs wrote:
> Zog The Undeniable wrote:
>
>
>>LEDs are also generally awful when run from NiMH cells.
>
>
> "Nickel Metal-Hydride batteries have a high capacity and a very flat
> discharge curve which maintains a cell voltage of 1.2V over ~80% of the
> discharge curve. This gives a nominal pack voltage of 4.8V which as you
> can see from the graph brings the mean efficiency up toward 70% and since
> the fully charged voltage of the pack is only 5.6V the maximum LED power
> is about 1.3W for a brief period and stays at 1W for most of the discharge
> cycle. If you do not want to modify the light I strongly recommend you use
> NiMH rechargeable batteries, you will get much longer run times."
> - http://www.ajjrice.plus.com/reviews/smart nova.htm

Yes, but LEDs are more voltage dependent than current dependent.
Conversely, incandescent lamps are excellent when run on NiMH batteries
because the cells have low internal resistance and can easily supply the
0.5A (or more) required by the bulb.

I thought the drop in output was quite scary when I measured it (I can't
remember if the alkalines were new or not - I think they may have been
used for half an hour or so). It was a full stop on the light meter at
a measured distance from the lamp, so the output was halved. Of course,
some LEDs may be better than others at coping with rechargeables - I did
the test on the (mediocre) Cateye HL-EL200 front light.

It's true that NiMH gives at least the same run time as alkalines in
heavy use. If you only use the light occasionally, the alkalines will
win because of the self-discharge of NiMH cells (something like 1% a
day, so they're all but dead after a few months).
 
In article <[email protected]>, Helen Deborah
Vecht ([email protected]) wrote:

> I've seldom seen a nightAUK with poor lights.

I /did/ get passed by a semi-visible Richard Phipps about 160 km into
the South Bucks Winter Warmer, but some new flatteries at the next
control sorted that out...

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Like Kant, it is my wish to create my own individual epistemology. But I
also wish to find out what is for pudding.
 
Dave Larrington wrote:

> I /did/ get passed by a semi-visible Richard Phipps about 160 km into
> the South Bucks Winter Warmer, but some new flatteries at the next
> control sorted that out...

Do his clones ever ride on the same Audaxes? Might explain the subtle
differences.

I saw one on the Invicta Hilly on Sunday.
 
Terry wrote:
> In article <[email protected]>, [email protected] (Tony
> Raven) wrote:
>
>> Terry wrote:
>>> I was horrified by the bloke cycling without lights in London the
>>> other night while carrying his young daughter on the crossbar. It was
>>> a cold night as well and the poor kid had no gloves.
>>>
>> Although I use lights in London to be honest they are not critical
>> unless it is raining. Street lighting is very good and visibility of
>> cyclists is not a problem in general.
>
> Ah, so you know the street I'm referring to, and are thus aware that it is
> a narrow rat-run with poor lighting, road-humps, cars parked on both
> sides, and cars entering and crossing having limited visibility due to
> parked cars?
>
> I'm so very glad that neither you nor the **** risking his kid's life is
> my dad.
>

Which part of "in general" did you not understand?


--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham
 
The (effective) battery life is nowhere near that touted on the
packaging IMX; I bought a Decathlon 3.99 one a couple of weeks ago,
claims to conform to French / German standards. It is the standard
Oxford clone oval 3 LED type but has side led's and a special lens
which considerably enhances the central led; it is Very bright. It does
not flash. I will be fitting it to my Audax bike (with a flashing one
as well to comply with the law AIUI)
 
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