Rear LED light effectiveness.

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

wrote in message
oups.com...
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, 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
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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
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wrote in message
oups.com...
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

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%20nova.htm

~PB

In article ,
(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