Bike light question: Flashing or Constant?

gaf1983

Both my front and back lights can be set to either flashing or constant.

Can anyone here tell me:

1. Which is safer, both from your experience as a cyclist, and if applicable, as a motorist?

2. Is there a legal requirement to use either option?

Thanks in advance.

scottreynolds

gaf1983 wrote: »

Both my front and back lights can be set to either flashing or constant.

Can anyone here tell me:

1. Which is safer, both from your experience as a cyclist, and if applicable, as a motorist?

2. Is there a legal requirement to use either option?

Thanks in advance.

I may be mad but I thought I heard a legal requirement for a constant front light -- flashing being illegal.

Deisetrek

gaf1983 wrote: »

Both my front and back lights can be set to either flashing or constant.

Can anyone here tell me:

1. Which is safer, both from your experience as a cyclist, and if applicable, as a motorist?

2. Is there a legal requirement to use either option?

Thanks in advance.

Stopped by a Garda on a main road last winter , had both front lights on flashing mode . He asked me ( nicely actually) to put one at least on "continuous on" mode as he said 2 flashers might confuse drivers into thinking it was an emergency oncoming vehicle . Seemed like a simple request rather than a legal requirement . He said , by the way it was no problem at the rear of the bike , as many rear flashers as you want .

CheGuedara

Well...

As both I personally put constant on both.

I find as a motorist that the constant rear red is much more useful in judging the distance of a cyclist travelling in the same direction. That said I have seen lads with small lights (knog frogs?) on the seat stays give a good outline of a cyclists position flashing or otherwise.

As regards a front light (if you're using it to see) only having it constant makes sense, and if it to be seen again I find judging distance better against the solid vs flashing settings. But that's just me

Not sure what the legal requirement is outside of having lights on once lighting is required - I would be surprised if it stipulated specifics (flashing/constant) *I stand corrected*

DirkVoodoo

Cycling in traffic, even a very bright rear light seems to get lost in the noise of car tail lights. Flashing definitely helps in this regard.

In the depths of winter or bad days, I put both my Smarts on, with one constant and one flashing.

Front light I leave on flashing, but it's a crummy little cateye that I will be replacing soon.

kenmc

DirkVoodoo wrote: »

Cycling in traffic, even a very bright rear light seems to get lost in the noise of car tail lights. Flashing definitely helps in this regard.

In the depths of winter or bad days, I put both my Smarts on, with one constant and one flashing.

Front light I leave on flashing, but it's a crummy little cateye that I will be replacing soon.

I do the same with my smart rears; frontwise i have one fenix on my helmet is on constant, the bar mounted one on flashing. I primarily want to be seen, flashing defo draws the attention.

Beasty

In the UK there is a definite legal requirement to have constant lights, but I am not sure if it's the same over here. I always have constant on the front (I need it anyway, as I am riding unlit roads, and need to see the potholes). On the back I have this:
http://www.wiggle.co.uk/p/cycle/7/Cateye_TL_LD1100_Rear_Light/5360025767/ which allows for one row flashing and one row constant

concussion

The legislation requires a 'fixed' light. Whether that means 'constant' or 'attached' I don't know.

cyclopath2001

Beasty wrote: »

In the UK there is a definite legal requirement to have constant lights, but I am not sure if it's the same over here.

It's the same here

Based on my driving experience I prefer to see a constant light on the front with a broad, but not intense beam as it makes it easier to judge the progress of a cyclist approaching me. On the back, I use one constant and one flashing. Don't forget a reflector.

One other thing is to give good consideration to how the lights are attached to the bike and aiming them for best effect. LEDS, especially need good aiming to be effective.

Lights attached to clothes or bags are useless on their own and don't meet the legal minimum.

Mucco

Beasty wrote: »

In the UK there is a definite legal requirement to have constant lights,

They changed that to allow flashing lights a few years back:

http://www.dft.gov.uk/pgr/roads/vehicles/vssafety/guidanceaboutlightsonpedalbi4556

NeilMcEoigheann

I was stopped by a member of the gardai who asked me to put my front light to constant, i told him that i didn't feel that the constant light attracted the same amount of attention as the flashing light stating that this was the reason that emergency service vehicles have flashing lights because they attract more attention. he accepted my argument and let me on my way.
i don't cycle with constant lights unless it is my super bright headtorch (yes it has dip beams, its that bright) and actually i have been pulled by a gardai just below 3 rock because he said that my light was too bright and he couldn't see. (which i thought was funny cos i got stopped at a checkpoint for not having lights a few days earlier....

BostonB

CheGuedara wrote: »

...I find as a motorist that the constant rear red is much more useful in judging the distance of a cyclist travelling in the same direction. ..

Probably a stupid question but why that is useful?

I generally have one of each (constant/flashing) front and back. As a driver I think the flashing ones get your attention better. I have one quite bright light on the front, as some of the park is unlit, and I couldn't see the road ahead with just the flasher. Also if one fails, or runs out of power you have a backup front and back.

I think many don't notice the new led's getting less bright after a month or so as they still work ok. But when you put a new set of batteries in you really notice the difference. You see a lot of people with very poor lights. They must never change the batteries.

Lumen

CheGuedara wrote: »

I find as a motorist that the constant rear red is much more useful in judging the distance of a cyclist travelling in the same direction.

BostonB wrote: »

Probably a stupid question but why that is useful?

You mean why is it useful that motorists can judge where you are, or why is a constant light better for this?

To the first: so they don't crash into you, and for courtesy reasons.
To the second: no idea, probably because the eye/brain can get a better fix on a constant source of light.

Thoie

From a motorist's perspective, bikes that stand out most clearly for me are ones with constant lights front and rear. What I've seen some people do, which I approve of (it's a personal thing) is put those little flashing ones on the back of backpacks (as well as the constant light in the proper place). It gives a good visual cue from a distance that it's a cyclist. I find that only flashing lights to the rear isn't as good, though that seems to contradict a few other drivers' comments above.

You're probably already aware of this, but I love seeing lights on a bike at dusk in the city. While there may be enough light from street lights for the cyclist to see where they're going, from the front seat of a car cyclists can "disappear" in and out of shadows, even if wearing hi-vis vests. I've no idea why, but the street lights, rather than illuminating the cyclist seem to provide camouflage instead

BostonB

The human eye sees worst in half ligh. Like dusk. Dunno where I read that.

BostonB

Lumen wrote: »

You mean why is it useful that motorists can judge where you are, or why is a constant light better for this?

To the first: so they don't crash into you, and for courtesy reasons.
To the second: no idea, probably because the eye/brain can get a better fix on a constant source of light.

You don't need to know distance to something to know there's something in front and you shouldn't crash into it. Knowing the distance better IMO can only be useful if you want to move out for he least amount of time and distance possible. Otherwise you'd give it a wide berth as possible.

It's a bit like late braking. IMO.

There probably been some reseach in avation regarding lights effectiveness when flashing or not.

Lumen

BostonB wrote: »

You don't need to know distance to something to know there's something in front and you shouldn't crash into it. Knowing the distance better IMO can only be useful if you want to move out for he least amount of time and distance possible. Otherwise you'd give it a wide berth as possible.

Try driving around with one eye shut and see how you get on without any distance perception.

Personally, I'd rather that drivers had an accurate idea of where I was.

CheGuedara

Lumen wrote: »

You mean why is it useful that motorists can judge where you are, or why is a constant light better for this?

To the first: so they don't crash into you, and for courtesy reasons.
To the second: no idea, probably because the eye/brain can get a better fix on a constant source of light.

That's pretty much it alright on both counts - not sure why the constant works better for me than seeing a flashing light. Maybe it's a dual effect that a flashing light commands attention and the solid allows more consistent tracking? It's entirely possible that as a cyclist that also drives that I'm more aware of cyclists on the road also which might confound things.

BostonB wrote: »

You don't need to know distance to something to know there's something in front and you shouldn't crash into it. Knowing the distance better IMO can only be useful if you want to move out for he least amount of time and distance possible. Otherwise you'd give it a wide berth as possible.

It's a bit like late braking. IMO.

There probably been some reseach in avation regarding lights effectiveness when flashing or not.

As much as it's blindingly obvious that if you can see something in front of you you shouldn't crash into it, it's always helpful to be able to range it relative to your position, speed and direction - this is surely undeniable? In the scenario of a cyclist with lights it surely allows more and better time before approaching the cyclist and safely overtaking (or otherwise) etc

Funsterdelux

Well, as a long time bicyclist I always used a constant front light, common sense, then when I was doing my driving theory test I read the rules of the road and found out that you can only have a flashing light on the rear of your bike.

I've just recently started driving, and now in the dark evenings I see that a lot of cyclists have the flashy, whitish front lights, which as a driver are not very useful, IMO.

irishmotorist

For me, it's gotta be flashing the whole way. The flasher will attract attention and make you stand out more - it makes it clear that there's something different to a car there. If a driver sees a flasher, they know it's a bike so are at least aware of this before attempting something unsighted.

CheGuedara

irishmotorist wrote: »

For me, it's gotta be flashing the whole way. The flasher will attract attention and make you stand out more...

Lumen

irishmotorist wrote: »

For me, it's gotta be flashing the whole way. The flasher will attract attention and make you stand out more - it makes it clear that there's something different to a car there. If a driver sees a flasher, they know it's a bike so are at least aware of this before attempting something unsighted.

This is why it's best to have both flashing and constant rear lights.

For the front I prefer a bright constant light, because flashing ones tend to be a bit dazzling to drivers.

rflynnr

Not entirely to the point but whether a light is flashing or not is largely irrelevant as regards permitting following traffic to judge your your proximity. Our brains are cued to changes in proximity by apparent changes in the size of objects on our visual cortex.

This is illustrated by a problem encountered with close formation night missions by the RAF during the Second World War: pilots had an unnerving tendency to crash into the plane in front. It emerged that pilots were unable to accurately judge the distance between planes because the bombers had a single red light under the tailplane, and the size of the light did not appear to change significantly as a following plane neared one in front. The solution was to place two red lights on either side of the tailplane so that as a following plane aproached the distance between the red lights would appear to grow, thus acting as a cue for the visual cortex/brain to judge distance.

Applying this logic to bikes would suggest placing a light on either side of your stays.

That said, our perceptual mechanisms governing what we pay attention to would appear to favour flashing lights: for the most part those mechanisms operate to suppress external stimuli so that we focus only on those stimuli that are significant. A constant red light is more likely to fall into the category of a suppressed stimuli than a flashing light would be.

tomasrojo

Constant lights on the bike, flashing lights on me.

Flasing lights: one red light on my midline at the back (on small rucksack or Sam Browne belt), two amber on my wrists.

It's effective; no idea whether it's optimal.

tomasrojo

I have read, in line with many comments above, that distance to a flashing light can be hard to judge, so that's why I went with both constant and flashing.

BostonB

Lumen wrote: »

Try driving around with one eye shut and see how you get on without any distance perception.

Personally, I'd rather that drivers had an accurate idea of where I was.

I know what your saying, but Unless people drive around with no headlights and one eye closed and theres no street lights, you'll always have some other term of reference. The road, verge, tress, a building. Maybe its a problem cycling at night on country roads, I have no experience of that. But the city/urban area it isn't. The problem is blending in against the background of car lights, and other visual distractions. You just need to catch the drivers eye, often their peripheral vision.

If you consider that theory that if visible and in safety gear vehicles drive closer to you, then, should we be that well lit up? (I don't agree with this btw).

I use both types of light, so obviously agree with you regardless of theory.

BostonB

As a driver I've noticed that I notice, bag mounted or helmet mounted lights quickly. So I actually have a small flasher hanging on back of my jacket. Too warm for the jacket at the moment though. Of course as you move the light can get covered. So useless on it own.

I guess the best is to have a couple of lights far apart. I'm guessing in the horizontal is more effective than iin the vertical.

CheGuedara

rflynnr wrote:

... Our brains are cued to changes in proximity by apparent changes in the size of objects on our visual cortex. ...Applying this logic to bikes would suggest placing a light on either side of your stays.

That would explain how I've found that seeing lights on bike seat stays in low light good alright.

Still find the constant light better though, but then again there's the question that as a cyclist myself do I naturally pay more attention to cyclists while driving and less require my attention drawn to their presence (as done by the flashing lights)?

Would be interesting to hear what pure non-cycling motorists (without anti-cyclist bias) would say constant vs flashing lights to see if theres a consistent differerence in preference.

tomasrojo

BostonB wrote: »

As a driver I've noticed that I notice, bag mounted or helmet mounted lights quickly. So I actually have a small flasher hanging on back of my jacket. Too warm for the jacket at the moment though. Of course as you move the light can get covered. So useless on it own.

I guess the best is to have a couple of lights far apart. I'm guessing in the horizontal is more effective than iin the vertical.

I guess blorg has the optimal set-up.

tomasrojo

CheGuedara wrote: »

That would explain how I've found that seeing lights on bike seat stays in low light good alright.

Still find the constant light better though, but then again there's the question that as a cyclist myself do I naturally pay more attention to cyclists while driving and less require my attention drawn to their presence (as done by the flashing lights)?

Would be interesting to hear what pure non-cycling motorists (without anti-cyclist bias) would say constant vs flashing lights to see if theres a consistent differerence in preference.

Not a motorist, so not the response you're looking for.

But I did get very distracted the other day by a flashing high-intensity front light on a bike approaching me. I did think it was too much. I had to turn my gaze away a little so as not to be dazzled. The light wasn't facing the ground, but absolutely horizontal.

GreeBo

I was always a constant light sort of guy, mainly because back then the only flashing ones were brutal 1st gen LED's.

Now I still use constant but I also have reflective strips that go on my ankles to keep any trousers tight that have flashing red lights on them.

What is it with people who will use a red light on the front or white on the back...are they just mad?

Traumadoc

Flashing lights are far more effective in drawing attention, warning of danger, thats why they are on slow moving vehicles ( amber flashing lights)

CheGuedara

Traumadoc wrote: »

Flashing lights are far more effective in drawing attention, warning of danger, thats why they are on slow moving vehicles ( amber flashing lights)

+


= Safe cycling?

tomasrojo

Is Flashing vs Constant the new Helmet thread?

Jip

GreeBo wrote: »

What is it with people who will use a red light on the front or white on the back...are they just mad?

At least they made some sort of effort, unlike the guy I came across n the dark last night along the North Road in the Phoenix Park with nothing whatsoever, no lights, reflective material on clothing or even reflectors on his bike. He blended right into the darkness.

BostonB

tomasrojo wrote: »

Is Flashing vs Constant the new Helmet thread?

Seems like lol.

I'm surprised we've not seen some euro neon lights yet.

CheGuedara

Jip wrote: »

At least they made some sort of effort, unlike the guy I came across n the dark last night along the North Road in the Phoenix Park with nothing whatsoever, no lights, reflective material on clothing or even reflectors on his bike. He blended right into the darkness.

Yea, I think everyone'll agree bike ninjas are bad (m'kay)

bob123456

Is the Q-Lite QL-257 too much?

CheGuedara

... 'subtle' subliminal messaging kicking in.... must purchase Garmin 705 then post on that credit card thread.... ...and blame bob123456 for the whole thing....

72hundred

CheGuedara wrote: »

I find as a motorist that the constant rear red is much more useful in judging the distance of a cyclist travelling in the same direction. That said I have seen lads with small lights (knog frogs?) on the seat stays give a good outline of a cyclists position flashing or otherwise.

I definitely find this as well. So my solution was two lights, one flashing and one continuous. Only problem is that it eats AA batteries in the winter months to keep a OK level of brightness. I was half thinking of getting a 18650 Li-Ion charged back light for powerful light and cheaper to recharge.

Civilian_Target

I use a constant front and two constant rear (a Smart 1/2 watt attached to the panniers, and a Blackburn Mars 3 attached to the seat post).

My thinking is that AAA batteries are cheaper than health insurance, never mind hospital fees, so I use my lights on heavily overcast days, or any time that is near dusk or dawn. At night, I also clip a reflective LED band at ankle level around each leg, and they flash.

When I'm driving or cycling, I generally find that flashing lights make it difficult to judge distances, particularly if the cyclist is in dark clothes, and that you are often much closer to the flashing lights than you think you are.

Relative to the consquences of not having them, bicycle lights are really cheap. I have very little time for people who don't use them.

Lumen

72hundred wrote: »

I definitely find this as well. So my solution was two lights, one flashing and one continuous. Only problem is that it eats AA batteries in the winter months to keep a OK level of brightness. I was half thinking of getting a 18650 Li-Ion charged back light for powerful light and cheaper to recharge.

Fenix do red diffusers, has to be the ultimate solution for 360 degree visibility.

BostonB

My guide is if any cars have lights on then, I should.

IM0

In my experience most flashing lights are stationary road works things, not the best impression to give a dozy motorist on his way home from the commute.

Then theres the 'annoyance' factor of flashing ones for people behind you.

tomasrojo

me@ucd wrote: »

In my experience most flashing lights are stationary road works things, not the best impression to give a dozy motorist on his way home from the commute.

Then theres the 'annoyance' factor of flashing ones for people behind you.

I disagree. I fell off my bike; if my light hadn't been set to flashing I'd be dead. Anyone who leaves their light set to constant is a fool.

(Just trying to helmetize this thread.)

BostonB

me@ucd wrote: »

In my experience most flashing lights are stationary road works things, not the best impression to give a dozy motorist on his way home from the commute.

Then theres the 'annoyance' factor of flashing ones for people behind you.

I dont get that. do motorists usually drive into roadworks?

coolbeans

A good rapidly flashing white LED is the only way to go in my opinion especially in the suburbs where you absolutely have to be seen from a distance. They draw far more attention. The only caveat on this is the RATE of flashing i.e. the flash needs to be rapid to be effective. If the flash is too slow as on some of the cheaper LEDs then constant is safer. I've used (not for long though) a front LED with a flash interval of almost a second which is just plain dangerous and does not a safe light make.

SerialComplaint

I find that my two white flashers on the front are pretty good at letting other traffic see me. It is not unusual to find that cars moving in the same direction as me pull out to their right, presumably having seen my flashing in their wing mirror.

Dr_Colossus

Just an FYI, was in the 2 euro shop on Thomas St on Sat and saw they were selling white LED front lights with a bike mount. Not having a front light since my last one was stolen I bought it to give it a go rather than spending out big money for something similar, for the sake of 2 euro I'm pretty impressed. Takes 4 AAA batters and with 5 LEDs it's pretty bright with a constant, quick flashing and slow flashing setting. Tried it this morning in the dark commuting through the city and could even see the flashes a good few yards ahead on the road.

cdaly_

Civilian_Target wrote: »

I use my lights on heavily overcast days, or any time that is near dusk or dawn.

I run my lights (flashing front and rear) any time I'm out, even in bright daylight. They probably don't do much in the bright but I reckon they provide some kind of draw-the-eye thing.


Rechargeable AA / AAA batteries, one set in the charger, one on the bike...

bob123456

If anyone is buying bike lights (or parts) there is free shipping to Ireland from Amazon atm on orders over 25pounds. Link

Thinking about going for the Reelight. Reviews

32€ SL100 | 43€ SL120

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*Hard to Steal
*No taking on and off.

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The Reelight SL120 Power backup flash while your wheels are in motion, crucially they continue to flash for up to 2 minutes after you have stopped thanks to the built-in capacitor which stores current while you are cycling.

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When pedalling your bike, friction free Reelight bike lights create their own energy by magnetic induction from the wheel mounted neodymium magnets, powering high efficiency flashing LEDs.

These lights can't fail on you like battery powered systems, therefore they also make a great set of backup safety lights to compliment your setup.