Is a flashing rear light during the day a good idea?

[Bonefishblues]

I'm pretty sure I'm given more space with a flashing rear. I use a Garmin "Radar" which has the added feature that when a vehicle approaches the rate of flashing increases.

Did 100 miles on the A4 yesterday and not a single close pass, many drivers going to the opposite carriageway when possible.

(NB. The Radar also lets me know when a vehicle is approaching on my computer - handy in some cases).

That's a clever piece of kit.

[Blondie]

Waste of time. Don’t bother.

[Bonefishblues]

Waste of time. Don’t bother.

With what? And why?

[Stevek76]

Bright daylight won't make much difference, dim conditions may help. Anecdotally I seem to get more distance in dimmer conditions with the light on than off, though I run it as solid regardless. It's probably borderline antisocial in terms of brightness too, not blindingly bright but bright enough that it likely blooms a bit in driver vision and I've always figured that's what encourages the passing at a greater distance.

Obviously will do diddly squat to the driver with their face stuffed in their phone!

[awavey]

I only use lights in daylight hours if the conditions warrant it and would aid visibility, so if its raining for instance Id use them or maybe misty/foggy, or if I was riding towards a setting sun.

but just standard levels of daylight I save the batteries and have them switched off.

I dont feel people give me more or less room whether they are on or not, but if it makes you feel better go for it, theres no right or wrong answer to it imo

[TrevA]

On a bright sunny day, I don’t think they make much difference, unless as previously mentioned, you are riding in a wooded area and in and out of shadow. On a dull winter’s day, I think they can help pick you out in the mirk. I have a a Cycliq Fly 6 rear camera/light. The camera is always on when I’m riding, and I’ll vary the light from nothing to flashing to very bright and flashing to steady according to the conditions. I think it’s better to have the light in pulse mode if possible, so it’s always on, but produces an intermittent brighter flash.

Cycling Time Trials (CTT) mandate a rear light for participation in time trials, but these tend to be on busier, more trafficked roads than many of us would normally ride on.

[mjr]

Nope, useless and antisocial because ones bright enough to be noticed by motorists are painful to riders and walkers, plus it helps fuel an expectation that cyclists should use the useless things and any without them can be abused.

[Blondie]

Waste of time. Don’t bother.

With what? And why?

See title of thread question

[Bonefishblues]

Waste of time. Don’t bother.

With what? And why?

See title of thread question

Thanks for the clarification. Your post followed mine which was itself commenting on a Garmin device, hence my query.

[ossie]

I'd say yes but dependant on your regular route, only you know it . Entering areas of shadowed tree cover on a bright day is a classic example that can cause issues.

I ride alone, so no problem with cyclists following and seriously I've never read of a walker being blinded by a rear cycle light.

There's no expectation on cyclists either, ignore this nonsense, you're battling with motorists. The choice is yours.

[rareposter]

I always use them. It's just part of riding a bike for me - lights, Garmin, saddlepack - just stuff I put on to go for a ride.

Not sure there's been any proper studies of how good, bad or indifferent they are. Anecdotally (as a driver),, it's far easier to spot a cyclist using lights then one without, even just a very brief glimpse in between traffic of a flashing red light ahead or a flashing white light off to one side is instant recognition that there's a cyclist there, there's no mistaking it for any other vehicle. In a few instances, I've been able to see lights far before I've been able to make out the rider or any movement.

There's a separate argument I suppose about the "expectation" to use them and what (if any) contributory negligence might arise from not having them on in the event of an incident. I guess that with the advent of daytime running lights on cars, it's become a sort of default "well everyone else has lights on therefore I should too" mindset. Evolution in action. Everything else gets brighter, you need to as well!

[Mike Sales]

Not sure there's been any proper studies of how good, bad or indifferent they are. Anecdotally (as a driver),, it's far easier to spot a cyclist using lights then one without, even just a very brief glimpse in between traffic of a flashing red light ahead or a flashing white light off to one side is instant recognition that there's a cyclist there, there's no mistaking it for any other vehicle. In a few instances, I've been able to see lights far before I've been able to make out the rider or any movement.

There is an interesting reference in Death on the Streets by Robert Davis.

A major piece of research in Britain gives an unwitting example of the difference between search and attention conspicuity.
In a pilot test the subject was tested on his ability to notice motorcycles with and without daytime lights after first being informed of the purpose of the study. Once aware of the purposes of the experiment, he had no problems in noticing all the motorcycles whether or not they used daytime lights.
Fulton E. Kirby C. and Stroud P. "Daytime Motorcycle Conspicuity" TRRL SR625, 1980.

[mjr]

Not sure there's been any proper studies of how good, bad or indifferent they are.

There have been many but the main one I recall finding a detectable benefit (I don't recall if it was even significant) was for those bike symbol projector front lights, back when they were a novelty. I'll dig out the details if wanted but it seems not directly relevant here.

Anecdotally (as a driver),, it's far easier to spot a cyclist using lights then one without, [...]

Yes, that's great when it's a conscientious cycle-friendly driver like you, but not so great when it's a bike-hater or simply an inattentive motorist for whom "spotted early" means "forgotten by the time they are reached".

There's a separate argument I suppose about the "expectation" to use them [...]

To be clear, I don't think there is currently any such expectation but I think it could easily arise if many cyclists keep routinely using lights in daytime, which is part of why I call such use an antisocial act.

[simonineaston]

My entirely personal feeling is that I get given more room from passing vehicles when I show a flashing daytime light on fairly narrow Welsh A and B roads.

I can imagine that effect would probably withstand scientific scrutiny. I wonder if anyone's done that sort of research. The trouble is, as has been suggested upthread that the sort of light that's visible in daylight, is also likely to be so bright as to have negative effects on those who may look into it, at night.
I'm at my wit's end to work out what goes through some bike/light users minds that I meet on cycle paths - not so bad on roads as the angle between oncoming bikes is wider. Surely it must have dawned on them that the super-bright light they have sort out has 2 connected properties 1) they are highly visible and 2) they can and often do, dazzle the oncomer, or follower, regardless of the type of vehicle the party is using, thus making it harder for them to see where they are going !! Same is true, but to a lesser degree, when said lights are used in daylight.

[ChrisP100]

I always have a flashing red light displayed, and in wet/poor conditions I have 2 on (I try to make sure they are out of sync).

It doesn't save me from every close pass but I'm sure most drivers give me extra room because of it.