Rear LED light effectiveness.

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_t o_reply*.com wrote in
message .99...
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

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_t o_reply*.com wrote in
message .99...
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 '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

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:

Following on from '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.