Author Topic: Visibility in fog  (Read 1569 times)

Kim

  • Timelord
Visibility in fog
« on: February 24, 2019, 03:02:54 pm »
While riding through the cloud over the Chilterns yesterday (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.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Visibility in fog
« Reply #1 on: February 24, 2019, 03:05:46 pm »
International Orange is the best colour of all for showing up in fog (IME). Much better than yellow.

<i>Marmite slave</i>

Kim

  • Timelord
Re: Visibility in fog
« Reply #2 on: February 24, 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.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Visibility in fog
« Reply #3 on: February 24, 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.

Kim

  • Timelord
Re: Visibility in fog
« Reply #4 on: February 24, 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.
To ride the Windcheetah, first, you must embrace the cantilever...

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Visibility in fog
« Reply #5 on: February 24, 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.
An ungovernable laughter, a joyous agitation which makes the summer stretching before you seem like an unrolling canvas on which you might draw those first rude pure strokes that are free. (Capote)

Re: Visibility in fog
« Reply #6 on: February 24, 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) 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.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Visibility in fog
« Reply #7 on: February 24, 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.
An ungovernable laughter, a joyous agitation which makes the summer stretching before you seem like an unrolling canvas on which you might draw those first rude pure strokes that are free. (Capote)

Re: Visibility in fog
« Reply #8 on: February 24, 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.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Re: Visibility in fog
« Reply #9 on: February 24, 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.

quixoticgeek

  • Mostly Harmless
Re: Visibility in fog
« Reply #10 on: February 24, 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
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Visibility in fog
« Reply #11 on: February 24, 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?

Kim

  • Timelord
Re: Visibility in fog
« Reply #12 on: February 24, 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...
To ride the Windcheetah, first, you must embrace the cantilever...

quixoticgeek

  • Mostly Harmless
Re: Visibility in fog
« Reply #13 on: February 24, 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
--
Beer, bikes, and backpacking
http://b.42q.eu/

FifeingEejit

  • Not Small just Far Away at the back
Re: Visibility in fog
« Reply #14 on: February 24, 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.

Morat

  • I tried to HTFU but something went ping :(
Re: Visibility in fog
« Reply #15 on: February 24, 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 :(
Tandem Stoker, CX bike abuser (slicks and tarmac) and owner of a sadly neglected MTB.

Re: Visibility in fog
« Reply #16 on: February 24, 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!

Re: Visibility in fog
« Reply #17 on: February 24, 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.

Re: Visibility in fog
« Reply #18 on: February 24, 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.

quixoticgeek

  • Mostly Harmless
Re: Visibility in fog
« Reply #19 on: February 24, 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
--
Beer, bikes, and backpacking
http://b.42q.eu/

Morat

  • I tried to HTFU but something went ping :(
Re: Visibility in fog
« Reply #20 on: February 24, 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.
Tandem Stoker, CX bike abuser (slicks and tarmac) and owner of a sadly neglected MTB.

Kim

  • Timelord
Re: Visibility in fog
« Reply #21 on: February 24, 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.
To ride the Windcheetah, first, you must embrace the cantilever...

Kim

  • Timelord
Re: Visibility in fog
« Reply #22 on: February 24, 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.

To ride the Windcheetah, first, you must embrace the cantilever...

Pingu

  • Put away those fiery biscuits!
  • Mrs Pingu's domestique
    • the Igloo
Re: Visibility in fog
« Reply #23 on: February 24, 2019, 08:11:18 pm »
Of course when riding rather than driving the fog did not seem so thick.

Do you wear glasses?

quixoticgeek

  • Mostly Harmless
Re: Visibility in fog
« Reply #24 on: February 24, 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
--
Beer, bikes, and backpacking
http://b.42q.eu/