Rear LED light effectiveness.



I

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Guest
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
 
I've made the same point many times i.e. that flashing. flickering or
otherwise intermittent lights are bad news and reduce visibility. This
based mainly on my observation from a drivers point of view, and the
logical argument that less light = less visibility.
The counter argument is that flickering will more likely attract
attention, but I am not convinced at all.

cheers

Jacob
 
I've made the same point many times i.e. that flashing. flickering or
otherwise intermittent lights are bad news and reduce visibility. This
based mainly on my observation from a drivers point of view, and the
logical argument that less light = less visibility.
The counter argument is that flickering will more likely attract
attention, but I am not convinced at all.

cheers

Jacob
 
> and the
> logical argument that less light = less visibility.

Does this extend to more posts = more visibility (I got yours twice :)
 
"Mark Thompson"
<pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com> wrote in
message news:[email protected]...
>> and the
>> logical argument that less light = less visibility.
>
> Does this extend to more posts = more visibility (I got yours twice :)

You aren't the only one with double vision ;-)

Cheers, helen s
 
[email protected] wrote:
> Driving home last night I overtook a cyclist with what from about 100m
> away I thought was a very dim constant rear light.

I have a cheapo rear LED light which I use in constant mode. One thing
I've noticed is that with freshly charged batteries, it is very bright
and hurts your eyes to look at it directly.

As the battery power dies though, the LEDs stay lit but appear dimmer
and this isn't always obvious as it it with a 'normal' bulb light.
Maybe this guy's batteries were also dying.

peter
 
wafflycat wrote:
> "Mark Thompson"
> <pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com> wrote in
> message news:[email protected]...
> >> and the
> >> logical argument that less light = less visibility.
> >
> > Does this extend to more posts = more visibility (I got yours twice :)
>
> You aren't the only one with double vision ;-)
>
> Cheers, helen s

oops sorry. Deleted it from google groups.

cheers

jacob
 
Following on from [email protected]'s message. . .
>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.
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.)

LED lights are usually powered from dry cells which go slowly from being
100% to empty. (Unlike rechargeables, which is why they are used on the
rear where you can't keep an eye on them.) Naturally you only
batteries when necessary so one day you'll think to yourself 'the lights
are a little feeble - to be replaced!' At that point a sequencing
flasher is borderline. (Note that typically one LED will have the same
brightness _each_ as five together - which is not the same experience as
most people have had with filament bulbs, where you get two half-bright
bulbs instead of one fully bright one. So 5 LEDs give plenty more light
than 1.)

A single flasher is probably not much good in built-up areas but if
bright will be fine in the country. Obviously the reason for using
fewer LEDs is extended battery life. This is where you can't make rules
but need to get people to ask themselves "can I be seen in the current
circumstances?".

FWIW I use five flashing about town except at dusk or wet when I use all
and in the country when it is properly dark a single sequencing flasher.

--
PETER FOX Not the same since the surrelism little carrot owl
[email protected]
www.eminent.demon.co.uk - Lots for cyclists
 
> oops sorry. Deleted it from google groups.

D'oh, I enjoyed reading usenet in stereo.
 
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.

~PB
 
Peter Fox wrote:

> Following on from [email protected]'s message. . .
>
>> 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.
>
> 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.)
>
> LED lights are usually powered from dry cells which go slowly from being
> 100% to empty. (Unlike rechargeables, which is why they are used on the
> rear where you can't keep an eye on them.) Naturally you only
> batteries when necessary so one day you'll think to yourself 'the lights
> are a little feeble - to be replaced!' At that point a sequencing
> flasher is borderline. (Note that typically one LED will have the same
> brightness _each_ as five together - which is not the same experience as
> most people have had with filament bulbs, where you get two half-bright
> bulbs instead of one fully bright one. So 5 LEDs give plenty more light
> than 1.)
>
> A single flasher is probably not much good in built-up areas but if
> bright will be fine in the country. Obviously the reason for using
> fewer LEDs is extended battery life. This is where you can't make rules
> but need to get people to ask themselves "can I be seen in the current
> circumstances?".
>
> FWIW I use five flashing about town except at dusk or wet when I use all
> and in the country when it is properly dark a single sequencing flasher.
>
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). Stick to alkalines, or, if financially possible, the Energizer
lithium cells which are the full 1.5V and have a more or less flat
discharge curve. If you need another incentive, they're very light in
weight.
 
[email protected] wrote:
> 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.

This post grabbed my attention because I use an LD600 in chasing mode
(alongside 3 steady rear lamps). It would be interesting to know,
though, whether the mode is generally useless or whether it was just
because the batteries were running low.

A few months ago I asked a colleague to follow me down the hill from the
office to judge the effectiveness of my reflective armbands. I think
that next winter I'll have to ask him to judge the effectiveness of the
LD600 in chasing mode.

--
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
 
On 14 Mar 2006 06:01:48 -0800, [email protected] <[email protected]> wrote:

> 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 agree. I've seen research that says chasing lights are particlarly
effective. However, I think that any bike light is too small a unit
for the chase to be visible from teh distance at which I want a
motorist to notice me. I use either steady or all-together flash on
my LED lights.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|
 
On 14 Mar 2006 06:01:48 -0800, "[email protected]"
<[email protected]> wrote:

>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?

Not knowing what's most effective, I hedge my bets:

On my seat post I have a Cateye TL-LD1000, used in random mode.
http://www.cateye.com/uk/productImages/big/TL_LD1000_lg.jpg

Mounted below the rear of my rack I have a Vistalite, used in chaser
mode.
http://www.pricepoint.com/images/styleImages/Z_225 VISSN0.jpg

Mounted on my mud guard I have a B&M Seculite Plus, only available in
constant mode.
http://www.bumm.de/docu/grafiken/330alk.jpg
--
Let us have a moment of silence for all Americans who
are now stuck in traffic on their way to a health club
to ride a stationary bicycle. -
Congressman Earl Blumenauer (Oregon)
 
Ian Smith wrote:
> On 14 Mar 2006 06:01:48 -0800, [email protected] <[email protected]> wrote:
>
> > 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 agree. I've seen research that says chasing lights are particlarly
> effective.

What research?

cheers

Jacob
 
Tom Crispin <[email protected]>typed

> Not knowing what's most effective, I hedge my bets:

Can't you find a friend to help you ascertain what's most effective?

One person tries some kind of light and rides off. The other stands
behind and watches, and/or gets into a car to observe.

A driver could follow the cyclist and the comment on what's effective
and where.

Cycling in groups will also help you ascertain which of your clubmates
have poor lights.

I've seldom seen a nightAUK with poor lights.

--
Helen D. Vecht: [email protected]
Edgware.
 
[email protected] wrote:
>I've made the same point many times i.e. that flashing. flickering or
>otherwise intermittent lights are bad news and reduce visibility. This
>based mainly on my observation from a drivers point of view, and the
>logical argument that less light = less visibility.

But there's no reason to think that a flashing light will have much less
light. If the LED is off half the time, you can drive it twice as hard
for the flashes without overheating it, and keep the same battery life.

The argument that it is harder to judge the position and speed of a
flashing light seems much more convincing.
 
The naked_draughtsman wrote:
>
> I have a cheapo rear LED light which I use in constant mode. One thing
> I've noticed is that with freshly charged batteries, it is very bright
> and hurts your eyes to look at it directly.

I used to be a complete advocate for LED rear lights set to flashing mode,
but this was probably because it was in the days before I discovered
retroreflective sticky tape and good capacity rechargeable batteries.
Having also been taking more interest in how I see others on their bikes at
night (cf. Cyclecraft), rather than how I think others see me on my bike,
I've decided that steady LEDs being powered by good batteries are much more
visible and it does seem easier to ascertain their distance.

Mostly I use the Vistalite VL300-series lights, though I have a Cateye LD600
on the trike; the former lasts for ages on a set of batteries and has a
built-in reflector, but the latter is much brighter. I augment the lights
with lots of red reflective tape on static parts of the bike, and amber on
moving parts, and I have a Vistalite Whaletail light set to flashing mode
attached to the top of my lid.

Becky
 
On Tue, 14 Mar 2006 19:51:53 GMT, Helen Deborah Vecht
<[email protected]> wrote:

>Tom Crispin <[email protected]>typed
>
>> Not knowing what's most effective, I hedge my bets:
>
>Can't you find a friend to help you ascertain what's most effective?
>
>One person tries some kind of light and rides off. The other stands
>behind and watches, and/or gets into a car to observe.
>
>A driver could follow the cyclist and the comment on what's effective
>and where.
>
>Cycling in groups will also help you ascertain which of your clubmates
>have poor lights.
>
>I've seldom seen a nightAUK with poor lights.

I don't quite know how to respond to that!

I suppose I don't really want to find out which is most effective 'cos
I like drawing attention to myself and looking like a Christmas tree.
--
Let us have a moment of silence for all Americans who
are now stuck in traffic on their way to a health club
to ride a stationary bicycle. -
Congressman Earl Blumenauer (Oregon)
 
[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? I got an LD600 "free" when I
bought my Streetmachine. My own thoughts when playing around with it was
that horizontal chase mode was liable to be masked by any horizontal
movement of the bike (and thus the light). Hence I tended to mount it
vertically (when I was using the LD600 rather than the TL-AU100BS).
--
These opinions might not even be mine ...
Let alone connected with my employer ...
 
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