Yet Another Cycling Forum

General Category => The Knowledge => Topic started by: Kim on 24 February, 2019, 03:02:54 pm

Title: Visibility in fog
Post by: Kim on 24 February, 2019, 03:02:54 pm
While riding through the cloud over the Chilterns yesterday (https://yacf.co.uk/forum/index.php?topic=111108.0) (in daylight), I was somewhat nervous about drivers approaching at speed from behind, and had to opportunity to observe a variety of audaxy cyclists passing in both directions in foggy conditions.  I started paying attention to what actually seemed to make people more visible from a distance.

Lights:

The brighter the better.  Standard Brompton rear lights were useless (in that the light disappeared while the profile of the rider was still clearly visible), which I'd extrapolate to the usual B&M-style StVZO designs, and most things you'd consider appropriate for riding in a group at night.  Obnoxiously bright COB rears and those intense flashy things you tend to see on TT bikes were best.

Obnoxious battery front lights of the type popular with roadies (Lezyne and similar) worked well, particularly the constant-light-with-bright-pulses effect.  StVZO dynamo fronts (presumably higher-end ones, given the demographic) were better than I expected.

Flashing was only really useful in as much that it allowed higher brightness - there was relatively little car traffic, so it wasn't a situation where a single light would be lost in the clutter.


Reflectors:

They did nothing.


Clothing:

This was really interesting.  Fluro yellow was good, but so was solid black.  Patterns which broke up the profile of a human amongst patchy light filtering through trees were bad.  Provis-style 100%-reflective was terrible, as it wasn't dark enough for reflected light from my front light to be visible, and it just blended into the greyness.


As a recumbent rider, I was aware that I lacked the profile of a human from behind.  I turned my Radbot up to Super Essex Disco Frenzy mode and hoped for the best.  I think this kind of situation is a strong argument for having a truly obnoxious rear light, and rarely using it.
Title: Re: Visibility in fog
Post by: mrcharly-YHT on 24 February, 2019, 03:05:46 pm
International Orange is the best colour of all for showing up in fog (IME). Much better than yellow.

Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 03:07:24 pm
International Orange is the best colour of all for showing up in fog (IME). Much better than yellow.

I noted that orange (which a couple of riders were wearing) was less good than either yellow or black, but that may be an artefact of my colour vision.  In less monochrome surroundings, it has a habit of blending in with greenery.

And for completeness light blue was unremarkable, though less invisible than the Provis.
Title: Re: Visibility in fog
Post by: tatanab on 24 February, 2019, 03:18:05 pm
This morning I drove 60 miles to a cycling event, and back.  On the way there It was rather foggy, 40 mph max in places.  Even encased in my car I was able to see the woman wearing a blue and white top long before I spotted the anaemic glow worm under her saddle.  It is sensible to use lights in such conditions, I did so later on, but please make sure they are powerful enough to be visible.  Of course when riding rather than driving the fog did not seem so thick.
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 03:19:05 pm
Of course when riding rather than driving the fog did not seem so thick.

That's an interesting observation, with important implications.
Title: Re: Visibility in fog
Post by: Cudzoziemiec on 24 February, 2019, 03:25:07 pm
Presumably down to speed and not having a windscreen for the fog to condense on. Though there's also the opposite phenomenon, when traffic ahead of you creates a hole in the fog making it seem less thick till you move into another lane.
Title: Re: Visibility in fog
Post by: Diver300 on 24 February, 2019, 03:44:06 pm
Many years ago I had a 12 V lighting system on a bike. The rear light was a car fog light, (https://www.ebay.co.uk/p/Genuine-HELLA-Rear-Fog-Tail-Light-2ne-002-985-001-Top-German-Quality/9021669655?iid=382572863126&chn=ps (https://www.ebay.co.uk/p/Genuine-HELLA-Rear-Fog-Tail-Light-2ne-002-985-001-Top-German-Quality/9021669655?iid=382572863126&chn=ps)) in which I ran a 6 W bulb.

One foggy night, I changed the bulb back to the standard 21 W bulb to deal with the thick fog.

I had the interesting experience of a car driver following, probably unable to work out what the vehicle in front was.

The driver overtook after the headlights from an oncoming driver's car had revealed I was on a bike, and not in a car with too few lights.
Title: Re: Visibility in fog
Post by: Cudzoziemiec on 24 February, 2019, 04:01:58 pm
Aren't fog lights designed to give a narrower (as well as brighter) beam pattern than standard head/tail lights, because of the dispersion of light by the fog? So that might be a factor in favour of the narrow-beam "daybright" tail lights.
Title: Re: Visibility in fog
Post by: Diver300 on 24 February, 2019, 04:07:07 pm
I think that car rear fog lights have a narrower beam, but I always assumed that the assumption was that was because they are designed to help the car to be seen further away on straight road.

If a car with rear foglights is at an angle to the following car, it's either one bend were the bend can limit visibility anyhow, or it is turning off the road and about to be out of the way.

I know there are exceptions to this, but I thought that was the general idea.
Title: Re: Visibility in fog
Post by: tatanab on 24 February, 2019, 04:08:04 pm
Aren't fog lights designed to give a narrower (as well as brighter) beam pattern than standard head/tail lights
Front fog light beams are broad and flat.  The idea being that they can pick up the kerb but not project light upwards to be reflected back by the fog.  Rear, I don't know.
Title: Re: Visibility in fog
Post by: quixoticgeek on 24 February, 2019, 04:35:49 pm
Clothing:

This was really interesting.  Fluro yellow was good, but so was solid black.  Patterns which broke up the profile of a human amongst patchy light filtering through trees were bad.  Provis-style 100%-reflective was terrible, as it wasn't dark enough for reflected light from my front light to be visible, and it just blended into the greyness.

Back at the end of the last century, the HSE did some research on what was the most visible colour for things at sea. They found that black and yellow were about on a par for visibility in that environment.

The big thing that many forget about fluorescent yellow as used in hivi's, is that the fluorescence requires UV to work. It's the action of UV light hitting it and it fluorescing that makes it so visible. If there is minimal UV, say due to fog, or the fact it's night time, it basically does very little.

I tend to wear black, I've had drivers pull along side to heckle me about not wearing bright colours "You seem to have had no such issues seeing me"

Quote
As a recumbent rider, I was aware that I lacked the profile of a human from behind.  I turned my Radbot up to Super Essex Disco Frenzy mode and hoped for the best.  I think this kind of situation is a strong argument for having a truly obnoxious rear light, and rarely using it.

Agreed. Having it, but using it sparingly is of course a good idea. I even have a hivi in my frame bag, just in case...

J
Title: Re: Visibility in fog
Post by: Jakob W on 24 February, 2019, 04:41:09 pm
I was pondering this issue today; I wasn't able to make my local group ride, but the fog persisted until quite late in the morning. Assuming one would only need an hour or three's battery life, what would be the forum recommendation for a fog-appropriate obnoxiously-bright yet cheap rear light?
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 04:46:25 pm
I was pondering this issue today; I wasn't able to make my local group ride, but the fog persisted until quite late in the morning. Assuming one would only need an hour or three's battery life, what would be the forum recommendation for a fog-appropriate obnoxiously-bright yet cheap rear light?

Bonus points for suggestions that don't require a sufficiency of exposed seatpost...
Title: Re: Visibility in fog
Post by: quixoticgeek on 24 February, 2019, 04:49:58 pm
I was pondering this issue today; I wasn't able to make my local group ride, but the fog persisted until quite late in the morning. Assuming one would only need an hour or three's battery life, what would be the forum recommendation for a fog-appropriate obnoxiously-bright yet cheap rear light?

Bonus points for suggestions that don't require a sufficiency of exposed seatpost...

I have a Cateye TL-LD570-R on my seat tube (not post), it's pretty obnoxious, and being cateye, you can mount it via a variety of means, including rack mounts, and belt clips. I has a built in reflector, so it also counts as a reflector... I also like my smart 1/2W led light.

J
Title: Re: Visibility in fog
Post by: FifeingEejit on 24 February, 2019, 06:08:10 pm
Car Rear fogs are as previously mentioned are nominally 21W incadescent non-hallogen bulbs
Normal Sidelights are 5w of the same.

The lenses are very different from normal rear lights as that Hella lamps picture shows, I suspect the purpose of them is just to be bloody bright unlike front fogs which as was mentioned the idea is to show you the side of the road and low enough to avoid the return.


Black makes sense in Fog as you've got maximum contrast with the colour of the fog.
Title: Re: Visibility in fog
Post by: Morat on 24 February, 2019, 06:31:59 pm
I have one of these
https://beryl.cc/shop/rear-burner
from the kickstarter when the company was still called Blaze. They attracted a lot of negative comment due to the weak magnets in the charging cable and the fact that the light can rotate in the magnetic mount. I think there may have been some firmware issues at first but they never affected me.

However, they are ridiculously bright and have really good batteries. They also have an auto-mode which I find useful if starting a ride which will continue into dusk, or riding through tree-tunnels. You can get many hours out of the "heartbeat" flash mode.

There used to be an alternate mount for racks but I can't see it on their website now :(
Title: Re: Visibility in fog
Post by: JohnL on 24 February, 2019, 07:14:53 pm
RNLI experimented with yellow, but went back to orange for the boats and life jackets as it stands out best in sea spray and fog etc.

The SAS used to wear black for counter terrorism as it stood out in smoke and tear gas filled rooms so they could see each other. They now wear grey presumably because they decided it was best that the baddies couldn’t see them...

I’m also on the hunt for a Frickin’ Lazer as a fog light. Extra bonus points for a mount that allows it to be switched on and off from the saddle. Many bonus points if it’s got a wired remote control so it can be positioned on the back of a rack beyond racks and saddlebags etc. That would be awesome!
Title: Re: Visibility in fog
Post by: hubner on 24 February, 2019, 07:22:25 pm
Personally I don't like extra bright dazzling lights, front or rear, especially flashing, so I don't use them.

I wouldn't get any just to use for the rare chance that it's foggy when I need to ride.
Title: Re: Visibility in fog
Post by: Ham on 24 February, 2019, 07:26:44 pm
Of course when riding rather than driving the fog did not seem so thick.

That's an interesting observation, with important implications.

Remembering always the reverse can be true if you are wearing eye protection of some sort.
Title: Re: Visibility in fog
Post by: quixoticgeek on 24 February, 2019, 07:31:23 pm
Personally I don't like extra bright dazzling lights, front or rear, especially flashing, so I don't use them.

I wouldn't get any just to use for the rare chance that it's foggy when I need to ride.

Depends how common fog is. Round these parts, it's surprisingly common. I often wake up to find I can't see the ground outside, from 6 floors up. Riding to work in those conditions, I run with my edelux II front light and a secular dynamo at the rear. But then I live in a swamp, so it's probably more common here...

J
Title: Re: Visibility in fog
Post by: Morat on 24 February, 2019, 07:33:56 pm
I prefer flashing, not because it's obnoxious (although it often is) but because it has become a visual cue that you're a bicycle and not a motor vehicle so motorists can react more quickly to a slow moving "target". That's just my theory.
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 07:47:34 pm
For 'fog' you can also substitute heavy precipitation, which causes additional vision problems for windscreen users.

My take on it is that it's probably worth having a rear light that's able to go up to 11, with some dimmer setting for normal use.  A dedicated 'fog light' will just have a flat battery when you eventually need it, unless you're in the habit of riding time trials down the A1.

My preference is for dynamo lighting, which means a StVZO static rear with a decent reflector as a primary rear light for riding in civilised conditions.  My default secondary is the ubiquitous Smart (or clones), but I'm now thinking something significantly brighter is called for in exceptional weather conditions.  Particularly if lying down on the job.
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 07:54:30 pm
I prefer flashing, not because it's obnoxious (although it often is) but because it has become a visual cue that you're a bicycle and not a motor vehicle so motorists can react more quickly to a slow moving "target". That's just my theory.

My theory is that if you're going to use a flashing light to grab attention or mark yourself as a pedal cycle, you also need a static one for the viewer to track between flashes.  Unless the frequency is seizure-inducingly high.

As I said in the OP, the lights which run constantly with pulses at full brightness seem to work well in this respect.  But two lights (one static, one flashing) has the advantage of redundancy, which is useful on the rear.


I intensely dislike flashing front lights, because they're rubbish for seeing where you're going by at night.  Yesterday's experience suggested that they weren't necessary for being seen in fog, either, though there may still be an argument for their use to mark yourself as a pedal cycle in more cluttered environments.  Nevertheless, my main concern in foggy conditions is being seen from the rear when I'm moving slowly, rather than being seen from the front when I'm moving quickly.

Title: Re: Visibility in fog
Post by: Pingu on 24 February, 2019, 08:11:18 pm
Of course when riding rather than driving the fog did not seem so thick.

Do you wear glasses?
Title: Re: Visibility in fog
Post by: quixoticgeek on 24 February, 2019, 08:31:32 pm
My take on it is that it's probably worth having a rear light that's able to go up to 11, with some dimmer setting for normal use.  A dedicated 'fog light' will just have a flat battery when you eventually need it, unless you're in the habit of riding time trials down the A1.

This is one of the reasons my battery lights are lights that take aaa or aa batteries. I can put lithium primary cells in there, and chances are if I don't use them for 2 years, they'll still have life. Also means they hold their charge better in sub zero conditions...

Quote
My preference is for dynamo lighting, which means a StVZO static rear with a decent reflector as a primary rear light for riding in civilised conditions.  My default secondary is the ubiquitous Smart (or clones), but I'm now thinking something significantly brighter is called for in exceptional weather conditions.  Particularly if lying down on the job.

The smart 1/2W lights are becoming harder to come by :(

J
Title: Re: Visibility in fog
Post by: Cudzoziemiec on 24 February, 2019, 08:34:35 pm
Personally I don't like extra bright dazzling lights, front or rear, especially flashing, so I don't use them.

I wouldn't get any just to use for the rare chance that it's foggy when I need to ride.

Depends how common fog is. Round these parts, it's surprisingly common. I often wake up to find I can't see the ground outside, from 6 floors up. Riding to work in those conditions, I run with my edelux II front light and a secular dynamo at the rear. But then I live in a swamp, so it's probably more common here...

J
I use a clerical battery.


I'll get my vestments.


And a serious comment: morning fog is also common in small, steep-sided valleys and around large rivers. Very common round here to go from sunshine up on the ridgy bit into fog down in the Severn Valley, for instance. Hill fog of course exists as a counterpoint to this.
Title: Re: Visibility in fog
Post by: Cudzoziemiec on 24 February, 2019, 08:36:10 pm
Oh, and the great thing about dynamo lighting in fog or heavy rain is that you can use it without worrying that you won't have enough battery left for the night time part of the ride.
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 09:20:12 pm
Of course when riding rather than driving the fog did not seem so thick.

Do you wear glasses?

You've misattributed the quote (that was tatanab), but FWIW, I wear glasses, and find that glasses with droplets on them are about as bad as my distance vision without glasses.

I haven't really had an opportunity to compare cycling with driving in fog.  Indeed, I don't think I've driven in proper fog more than a handful of times.
Title: Re: Visibility in fog
Post by: Ben T on 24 February, 2019, 10:10:46 pm
I rode in the fog today, had rear cat eye spare on as well as the dynamo rear, and yellow gilet. Radbot probably better but not worth having one just for the handful of times a year there's fog, the combination I've got is probably ok.

But was shocked at the amount of drivers that seem to think it acceptable to drive around in fog with no lights on at all!

I've never found car front fog lights make much difference, maybe I'm looking wrong or it's the wrong sort of fog for them? The button is an easier way of getting the main head lights to switch on if the sensor decides it's not dark. (I could move the switch to always on, but I'd have to remember to put it back to auto)
Title: Re: Visibility in fog
Post by: rogerzilla on 24 February, 2019, 10:34:54 pm
Front fogs are useless on most cars.  You can't normally tell from the driver's seat whether they're on or off.  The ones on my old Jimny did sort of work but the ones on the MX-5 and Mazda 6 are just for sporty looks, as far as I can tell.
Title: Re: Visibility in fog
Post by: andrew_s on 24 February, 2019, 10:57:27 pm
Should your riding in fog encompass the hours of darkness, an StVZO front light (preferably mounted fairly low) is considerably better than any other light.
If you are to see where the road goes, you want to minimise the amount of brightly lit fog between your eyes and the road. Head mounted lights are particularly bad, verging on unusable.
Title: Re: Visibility in fog
Post by: Kim on 24 February, 2019, 11:10:20 pm
Should your riding in fog encompass the hours of darkness, an StVZO front light (preferably mounted fairly low) is considerably better than any other light.

Absolutely agreed.  Best not to mount your head fairly low at the same time, thobut.
Title: Re: Visibility in fog
Post by: SA_SA_SA_SA on 24 February, 2019, 11:43:32 pm
Many years ago I had a 12 V lighting system on a bike. The rear light was a car fog light, (https://www.ebay.co.uk/p/Genuine-HELLA-Rear-Fog-Tail-Light-2ne-002-985-001-Top-German-Quality/9021669655?iid=382572863126&chn=ps (https://www.ebay.co.uk/p/Genuine-HELLA-Rear-Fog-Tail-Light-2ne-002-985-001-Top-German-Quality/9021669655?iid=382572863126&chn=ps)) in which I ran a 6 W bulb. ....
That seems rather expensive:
For years my main dynamo rear lamp was a ring rear fog lamp* lit to tail lamp level with 1.5Watt Sturney Archer MES bulb (approx 15lumens) till unavailable then 2.4W bulb(21lumens) in it (cycle bulbs trade brightness for life compared to car bulbs such as your 5Watt (approx 36lumens perhaps?)...): because it had a nice wide beam compared to then filament cycle lamps: it lives on with a power led emitter pointing at the reflector (IQ style :) ) and a salvaged Spanninga Arcus 180 Circuit board.
It seems to have forgiving optics: I once tried the same idea in a  different kind/make and it was rubbish....

*only white versions seem available now at 4.75+P&Phttps://www.ebay.co.uk/itm/Ring-Automotive-140mm-Rectangular-Clear-Lens-Reversing-Light-Car-Lamp-RL013/272106273317?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 (https://www.ebay.co.uk/itm/Ring-Automotive-140mm-Rectangular-Clear-Lens-Reversing-Light-Car-Lamp-RL013/272106273317?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649)

I suppose running an extra heatsinked LED at >1watt from a battery would give a real fog light...
NB on battery emergency fog lights:  if one cannot raid a headtorch etc, should batteries not be available in a nearby garage?  Currently in fog I would use two moon pulsors at full power but I would probably be prone to listening and scurrying out of the way rather than relying on driver sense....
You could argue that the existance of mandoratory car fog lamps encourages bad driving...
Title: Re: Visibility in fog
Post by: Pingu on 24 February, 2019, 11:52:00 pm
Of course when riding rather than driving the fog did not seem so thick.

Do you wear glasses?

You've misattributed the quote...

Soz, deleted the wrong bit of the post. I meant to ask tatanab if they wear glasses.
Title: Re: Visibility in fog
Post by: mzjo on 25 February, 2019, 12:00:07 am
International Orange is the best colour of all for showing up in fog (IME). Much better than yellow.

I noted that orange (which a couple of riders were wearing) was less good than either yellow or black, but that may be an artefact of my colour vision.  In less monochrome surroundings, it has a habit of blending in with greenery.

And for completeness light blue was unremarkable, though less invisible than the Provis.

Orange hi-viz is what is pretty much universal for french hunters ("chasseurs") and beaters, particularly during drives for wild boar. Often coupled to camouflage markings. Perhaps that makes them melt into the countryside in the eyes of the prey while still being visible to their mates. Doesn't prevent beaters being mistaken for targets, mind.
Personally I don't like extra bright dazzling lights, front or rear, especially flashing, so I don't use them.

I wouldn't get any just to use for the rare chance that it's foggy when I need to ride.

Depends how common fog is. Round these parts, it's surprisingly common. I often wake up to find I can't see the ground outside, from 6 floors up. Riding to work in those conditions, I run with my edelux II front light and a secular dynamo at the rear. But then I live in a swamp, so it's probably more common here...

J
I use a clerical battery.


I'll get my vestments.


And a serious comment: morning fog is also common in small, steep-sided valleys and around large rivers. Very common round here to go from sunshine up on the ridgy bit into fog down in the Severn Valley, for instance. Hill fog of course exists as a counterpoint to this.

Indeed, the Severn Valley is notorious for it. I have photos with Crickley Hill standing out as an island in the middle of a sea of fog.
Where I am now fog is more a thing of the midnight to 3am shift. Windy little country roads with no white lines and 20m visibility surrounded by ditches and very solid trees. No fun at all!!
Title: Re: Visibility in fog
Post by: tatanab on 25 February, 2019, 06:56:41 am
Soz, deleted the wrong bit of the post. I meant to ask tatanab if they wear glasses.
Yes I do.  In fog or rain I wipe the outside often to keep them clear.
Title: Re: Visibility in fog
Post by: quixoticgeek on 01 March, 2019, 10:44:27 pm

For the 3rd, or possibly the 4th day this week I woke to thick fog. Was off on a DIY 200, which I did with my dynamo light on for the whole ride. The fog became that sort of drisel that you don't actually notice falling, but when you stop you notice everything is wet...

So yeah, fog is common round these parts...

J
Title: Re: Visibility in fog
Post by: drossall on 02 March, 2019, 08:39:30 pm
I was on the same event as Kim, and I don't actually remember riding in anything like that in decades. Even then it was only foggy on the tops, as Kim says - down in the flatlands, on the way from Aylesbury, it had all cleared. As I mentioned elsewhere, the sneaky trick I used was accidentally to turn up one hour later than I should have done for the start, thus allowing the fog to clear more by the time I went through, but it was still thick around Christmas Common, and I was making some of the same observations (with basically the same conclusions) as did Kim.

It did remind me of riding home, maybe the first or second year I was at senior school. That one was so thick that my Mum came out walking, looking for me. As I remember it now, I couldn't even see her on the pavement next to me. Youthful innocence, but I felt perfectly safe because the cars basically couldn't move at any speed, as they couldn't even tell where the road was.
Title: Re: Visibility in fog
Post by: Kim on 02 March, 2019, 09:14:50 pm
There was some decent fog on the train down from Brum, to the point where the conductor got confused and announced that we should "be careful when disembarking the plane, as there's a big drop".  I assumed it had cleared up by the time I reached Aylesbury, but it was evidently lingering to the west, as we were back in it before turning off the B4009.

It wasn't quite as bad as the fog we had over the moors on the FNRttC to Blackpool last year - that was proper need-GPS-to-find-the-other-side-of-the-road stuff, but the main safety fear was not being able to see where you were going, and the motorists were in the same boat.

Certainly the worst I've experienced in daylight for a few years, though, and the first time I've experienced it in the company of large numbers of other cyclists.
Title: Re: Visibility in fog
Post by: fd3 on 02 March, 2019, 09:47:42 pm
In heavy rain and fog I supplement my dynamo light with Exposure joystick and rear light mounted on helmet.