Flashing rear light enhances driver perception of cyclist ahead

slideshow bob

Interesting research article, even if the experiments were somewhat simplified.

https://www.sciencedirect.com/science/article/pii/S0001457523004657

In conclusion, flashing rear cycle lights, regardless of reactive technology, enhanced drivers’ perception of a cyclist ahead, notably in terms of their judgements of distance to that cyclist.

tomasrojo

I seem to remember that it was common enough to claim that drivers had trouble perceiving how far away a cyclist was based on just a flashing light (which I think led some people to use one fixed light and one flashing), and that flashing lights were supposed to have an effect of causing some drivers to fixate and bend their trajectory towards the cyclist (can't remember whether there were studies this was based on).

I would definitely believe that a flashing red light is emblematic of a cyclist for just about everyone. I'm not sure drivers behave any better on that basis though. Based on my experience of "dressing like a cyclist" versus "dressing like a normal person", it might be possible that the behaviour of drivers gets worse when they realize who's up ahead.

I like a medium-intensity fixed light, but with a big face, or two lights of medium intensity mounted contiguously, for similar effect. Not sure it works as well as high-intensity or flashing lights, but it's very visible, without sort of pleading to be seen, which I think can set off people who have been listening to Newstalk.

tomasrojo

It doesn't look an amazing difference in how drivers perceive distance but I might be misunderstanding.

beggars_bush

Flashy red light makes you stand out from other traffic though. I don't want to look like a car with dodgy rear lights from behind

Those flashing red strobe lights can be seen from over 1km away, apparently

CramCycle

My reading of the paper is that technically, when pre warned, motorists will react to static lights quicker but are slightly better at depth perception with flashing lights. In reality, it's hard to take anything from it the differences are so minute it can't tell you anything other than if drivers are focused, they will see someone at roughly the same time if paying attention (and at the distance and lighting used for the test).

tomasrojo

https://www.boards.ie/discussion/comment/122685377#Comment_122685377

Reminds me of that Australian hi-viz study, where the participants turned out to be pretty good at seeing the cyclists with no lights and no hi-viz, and the people doing the study assumed the participants were so keen to perform well in the study they were far more vigilant than was usual in the scenario they were trying to recreate.

fat bloke

Garmin rear light is amazing in terms of visibility from way off. I always use it in flashing mode, saves the battery too.

SchrodingersCat

https://www.boards.ie/discussion/comment/122685231#Comment_122685231

flashing lights were supposed to have an effect of causing some drivers to fixate and bend their trajectory towards the cyclist (can't remember whether there were studies this was based on).

I can’t comment on particular with road drivers, but this phenomena is called “target fixation ”. It has been known since WWII where fighter bomber pilots would end up flying into targets instead of bombing them.

It is a lesson why drivers should look at where they want to go, not stare at what they don’t want to hit.

I’ve noticed it while cycling in painted cycle lanes. Cars that are going past will sometimes drift in towards me over the line before correcting their trajectory.

I can vouch on what you say about drivers treating you differently if you are “dressed like a normal person” vs “dressed like a cyclist”. Drivers seem to be more forgiving and respectful if you are dressed more like them than in the full gear. There is something psychological going on there.

magicbastarder

I was always a practitioner of the 'one flashing, one steady' option when I was commuting. Not that I was a true believer of the theory, but I was hedging my bets. Plus, to have two lights for redundancy.

But one context I think flashing lights are probably good in, is rain. A tired or distracted motorist looking in a rain spattered wing mirror might not correctly interpret a steady light reflecting off multiple droplets, where a flashing light will be a more obvious signal of a cyclist.

Nigzcurran

I drive a van for a living on all sorts of roads and for me personally I can see a flashing red light far more easier than a static one, having both is definitely the best option especially now coming into the dark wet mornings. Some of the white front lights can be a bit blinding, could be they are pointing upwards too much but id still prefer that to a cyclist who has no lights

standardg60

I would have thought it's a no brainer, flashing lights are simply more attracting/distracting to the human eye and are noticed sooner. A flashing light in a wing mirror will draw your attention before you even look at it.

It's no different to an indicator, if indicators didn't flash they would be far less noticeable. Same for emergency vehicles.

sudocremegg

No brainer really, coupled with hi visibility reflective clothing you have a better chance of being perceived.

magicbastarder

FWIW, and this only happened once; I was in the clontarf cycle path at the final section near east point, and briefly thought I could see a car heading straight for me, albeit some distance away. Probably took less that a second to cop that it was a cyclist with two steady white lights, but very briefly my brain interpreted them as car headlights. That fed into my decision to go one steady, one flashing.

rflynnr

I used to use two lights - one solid, one flashing - based on the logic outlined above. Last year, I bought a Magicshine SeeMe 300 which does both. A permanent red and a pulsing one (with two different LEDS). Just a bit handier then two (and came with a great under-saddle fitting option along with the standard seat post mount).

Johnners1878

https://www.boards.ie/discussion/comment/122686741#Comment_122686741

That looks impressive & good value too. Is it available locally or just online?

tomasrojo

Thing is, whatever about the fixation theory and judgment of distance theory, I actually think there's a balance between being visible and drawing too much attention to yourself. The worst incidents I've had on the road haven't been from people failing to see me, and in any case I've gotten very good at knowing when someone hasn't seen me (usually because they're not thinking two moves ahead in a manoeuvre) and dealing with it. The worst have been people deciding to punish me or teach me a lesson based on some demented Newstalk logic or just standard bully personalities. So going through estates with bored people hanging around on corners I like to turn down the conspicuity considerably. And once I'm very adequately visible on the main road I don't want to get to the point of demanding or pleading to be seen, because that seems to bring the worst out in some people.

tomasrojo

I suppose part of my problem with a lot of road safety thought is that it's based on the model of rational drivers who are doing their best, but there is a not imperceptible minority that is nothing like that, and though it's impossible to know the extent, these awful people, through punishment passes and prank passes that go wrong, make up part of the tragic "they came out of nowhere" stories that gardaí hear every year.

tomasrojo

I should say that recently on two separate occasions a pedestrian and a driver stopped me to tell me how good my lights were, so I'm pretty sure they're adequate.

tomasrojo

My basic approach (not based on anything more scientific than anyone else's) is that lower-intensity lights should be set to flash, and higher- to steady; though maybe in dense fog it's good to go for broke.

CramCycle

Just not a fan of flashing lights on experience with target fixation (they used to be banned on Audaxes) and my lights are bright enough in rural scenarios that people not paying attention slow down as if I'm a slow moving motorbike or car with only one front light. Like Tomasrojo, I have gotten compliments for my lights. I also think that my lights are bright enough that if flashing would be a decent distraction.

If research comes out showing me conclusively wrong, I'll adapt, I til then it's solid lights for me.

magicbastarder

well, the purpose of flashing and steady can be separated into two - flashing is for others to see you. steady is for others to see you, and for you to see. so i'd agree that a flashing light has done its job once it's noticed.

a clanger

https://www.boards.ie/discussion/comment/122685729#Comment_122685729

I agree and coupled with the radar its the best bit of kit I ever bought. I get a visual and aural warning of approaching traffic reminding me to keep in and pay attention.

rflynnr

https://www.boards.ie/discussion/comment/122686810#Comment_122686810

I bought it direct from Magicshine for US$60. Shipping was free. Apparently it has some class of brake light setting but I've never engaged it.

rflynnr

Incidentally I also bought one of their Alty 1500 front lights with which I'm also very happy. The initial appeal of both was the mounts to the honest. I'd gotten fed up of fiddling with rubberstraps in the dark before the commute home. I used to be kind of sniffy about Magicshine because they were Chinese. Then I reflected that a) this was just a tad racist and b) because VIRTUALLY EVERY OTHER LIGHT I'D EVER BOUGHT WAS ALMOST CERTAINLY MADE IN CHINA.

Seth Brundle

Out of curiosity, the German StVZO (road traffic laws) prohibit flashing lights on bikes (but apparently it goes unenforced). Does anyone know the logic behind this prohibition?

standardg60

https://www.boards.ie/discussion/comment/122688185#Comment_122688185

Germany's StVZO bike light regulations dictate that flashing bike lights are not permitted on either the front or rear of a bike. The regulations state this is because flashing patterns can be distracting to other road users. Flashing bikes are also outlawed in the Netherlands and Austria.5 Oct 2023

Funny, I thought that was the entire point.

Wishbone Ash

https://www.boards.ie/discussion/comment/122688185#Comment_122688185

It may go unenforced but they still aren't available on German online sites.

Flashing lights on a bike were illegal here until about 10/12 years ago IIRC.

khamilton

I turned my lights to solid rather than flashing when cyclepacking around central Europe this summer, and can't recall seeing ANY flashing bike lights in the 4 countries I visited.

beggars_bush

The flashing setting lasts much longer in terms of battery so if I'm out for 3 hours+ it'll be on flashing

secman

Yep on flashing, recently bought the Megane radar rear light and only use it on Flashing mode. The great thing about them is, as soon as they pick up a car they Flash more .

John_Rambo

I'm a bit obsessed with lights on the bike. When the flashing lights came out first I was all over them, got a set in the Netherlands. I'd a few comments from drivers in traffic about the legality of them and how they blinded drivers. I also had a trailer for the kids (15 years ago) and I was accused of child abuse and child endangerment from drivers!

Attitudes are slowly changing.