Point source rear lamps and distance judgement?

[SA_SA_SA]

I have come across the idea that approved (K~ Stvzo) point source (eg single 5mm LED) rear lamps like the B&M DToplight or Basta Ray LED are terrible for distance estimation of a cyclist (in the absence of streetlamps but when a the following vehicle is on dipped beam):

Do any driving members have experience of this?

How inaccurate are the resulting estimates?

Was the range if dipped beam lighting reflectors/the cyclist enough to compensate for the inaccurate estimate?

I presume the movement of the lamp against road background provides some extra clue.

I wonder why the lamp manufacturers didn't just fit a reverse mounted red led* in a conventional prism lens and reflector unit as used by previous rear filament lamps: marketing? designer looks over function?

Also, do any members feel dazzled by such lamps when following a cyclist equipped with one?


* (like the Spanninga Luceo/Micro FF LED front lamps)

[Brucey]

I agree single LEDs and other point sources are terrible for distance (and speed) estimation. There have been studies re motorcycles that have concluded similar ref daytime headlight use.

One of my pet ideas is that front and rear lights should (at least, or also) have 'marker' LEDs within the housing at an agreed spacing, so that it immediately says 'bike light' and gives good distance cues.

cheers

[Cunobelin]

Surely this is academic?

If you see a light ahead and cannot judge the distance.... Then slow down and drive appropriately

The first case scenario is the driver who thinks they can judge distance, and does not modify their behaviour,endangering the cyclist when they get it wrong

[Brucey]

if motorists drove with due care, we arguably wouldn't need lights at all....

Back in the Real World, we do, and the more clearly they indicate the speed and distance of the cyclist to other roads users, the less likely there is to be an 'accident'.

cheers

[meic]

Back in the Real World, we do, and the more clearly they indicate the speed and distance of the cyclist to other roads users, the less likely there is to be an 'accident'.

I reckon that the number of crashes avoided by confused drivers keeping further away will outnumber those caused by drivers who want to shave you off judging it incorrectly.

[Brucey]

I am forced to wonder; who is to say that they are exclusively confused in such a 'safe' fashion?

cheers

[thirdcrank]

I wonder if this is partly what people are used to, although you might assume people were used to LEDS on bikes by now.

I remember being on nights in the mid 1990's and seeing a bright red light ahead - obviously a vehicle but I couldn't see what it was. It was so bright I thought it must be a motor vehicle but the wobble suggested a cyclist riding uphill. It was a cyclist. John Franklin suggests that two lamps may be mistaken for a motor vehicle.

(It reminds me of a shaggy dog story about tigers prowling about at night in pairs with one eye shut to avoid being shot between the eyes.)

[SA_SA_SA]

Two leds in the same lamp will merge into one pretty quickly.

For two separate lamps: a mudguard and rack one vertically separated might be best.

[robc02]

John Franklin suggests that two lamps may be mistaken for a motor vehicle.

He does indeed. I have seen this myself,as well - a cyclist with two bright lights, one either side of the back wheel, looked like a car in the distance rather than a cyclist close to!

John Franklin also recommends "looking like a cyclist" e.g. having reflective pedals.

I would have thought a point source lamp would be OK if supplemented by other lamps or reflectives as long as the result still looks like a cyclist. So a mudguard reflector and pedal/shoe reflectors ought to do the job.

[SA_SA_SA]

Thanks for responses so far.

Any more driving cyclists wish to comment?

[[XAP]Bob]

The number of cars I see with broken lights I pretty much assume everything is a broken down tank (i.e. not going to give way if i hit it)

Last week I hopped out of my car at lights and ran to the car in front to point out that both of their rear lights had failed. I suggested that they used their rear fog lights until they could it fixed.

I don't find point sources hard to spot, or judge - I DO find many car lights, modern "white" street lights and modern traffic lights dazzling - to the point where I have to slow significantly after them until I can see properly again.

[thirdcrank]

.... as long as the result still looks like a cyclist. So a mudguard reflector and pedal/shoe reflectors ought to do the job.

You could do an Alas Smith and Jones sketch (but who remembers that programme anyway? )

"Chap out here wants a m-u-d-g-u-a-r-d r-e-f-l-e-c-t-o-r....would that be for an ordinary bicycle Sir? or perhaps a safety?"

By coincidence, I found two mudguard reflectors in my vast stock of hard-to-find cycle parts and accessories AKA junk, only the other day on one of my regular stock takes AKA deciding what might be binned. I bought them about a dozen years ago when after a fruitless trail round West Yorkshire's bike shop I discovered they had three in a drawer at Ellis Briggs and bought the lot.

Anyway, fitting a mudguard reflector may not make you immediately recognisable as a cyclist.

[thirdcrank]

Sorry - memory failure. Not Alas Smith and Jones but pretty much the same cast in Not the Nine O'Clock News.

http://www.youtube.com/watch?v=dSINO6MKtco

[robc02]

Anyway, fitting a mudguard reflector may not make you immediately recognisable as a cyclist.

Not on its own, but it does supplement the point source LED meaning that there is no longer a single point of light - when illuminated by a vehicle's headlights, of course. John Franklin's argument was that this in conjunction with pedal reflectors (or equivalent) makes you more likely to be recognised as a cyclist.

[thirdcrank]

... Not on its own, but it does supplement the point source LED meaning that there is no longer a single point of light - when illuminated by a vehicle's headlights, of course. John Franklin's argument was that this in conjunction with pedal reflectors (or equivalent) makes you more likely to be recognised as a cyclist.

Sorry, the point I was trying to make was that it's a while since it was possible to buy mudguard reflectors so there must be plenty of people around who wouldn't make the connection between mudguard reflector and cyclist, no matter what other lighting equipment was fitted.

My reason for mentioning JF was to point out that there is an alternative view to the "more the better" line. I'll let sleeping dogs lie with regard to pedal reflectors.