Lighting plan

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As a professional photographer and enthusiastic filmmaker, light is something that matters to me. As a (now) keen cyclist, it might even keep me alive.

As we all know, lights on a bike serve two purposes – allowing you to see stuff at night (illumination), and allowing you to be seen by other road users (conspicuity) at night and on dull days. These things have to be considered independently. Conspicuity is aided and abetted by reflectors and high-vis clothing, and is probably the only thing that urban cyclists, in their brightly lit environments, need to think about. Here, in our very rural setting, we have extremely dark nights – so good illumination is important. And being Normandy, during winter we often have rather dark days, making conspicuity all the more important.

Of course, illumination is an issue only at the front – rear lights are purely about conspicuity.

Axa Pico 30 front light

Axa Pico 30 front light

Our Gitane Organ e-bikes came fitted with reasonable quality lights. The front one is an Axa Pico 30 which, as the name suggests, is a 30-lux model. It has a built-in white reflector. It’s not bad, as cheap lights go (you can pick these up for around 18 euros). It illuminates the road just ahead of the bike tolerably well, and offers good conspicuity. But it’s not enough for cycling dark country lanes with confidence. It’s good to know it’s there, though, and always available (see later) as a get-home option.

At the back is a JOS Spanninga taillight in which the light and reflectors are built into the battery, and so sit just under the rack. The LEDs form a very bright strip at the top, wrapping around to provide some side-on conspicuity. The reflectors are quite large.

Image Copyright © Steve Mansfield-Devine. All rights reserved. Plus Registry 01-AA-660.

Rear light built into the battery

Both front and rear lights run off the bike’s main battery, so using them does affect the range of assisted pedalling a little (quite how much is yet to be seen). But that range is far more than we plan to cycle in a day anyhow.

The bike’s electronics shut down the assist before the battery is completely drained, to avoid damage to the cells. But even when this happens, the manual claims that we have up to two hours’ worth of power left for the lights. And there will simply never be a case where we’ve cycled so far that the assist isn’t available, it’s night and we’re more than two hours away from home. If that kind of situation ever arose, frankly, I’d check into the nearest hotel or phone a friend to come and get us.

What this means is that battery power simply isn’t a consideration. I had thought of fitting dynamos to the bikes as a back-up in case any battery-powered lights ran out of juice. But now I simply don’t see that as an issue, which simplifies matters somewhat. On a conventional bike, without its own power source, I’d definitely use a mix of battery and dynamo lights.

Additional lighting

To be honest, even before we got the bikes I’d planned to use additional lights. I’m of the opinion that you should be lit up like Blackpool Illuminations at night.

At the front, I want to be able to see the road more clearly, and to throw enough light that oncoming drivers know I’m there even before they round the bend. At the back, I want drivers to be aware of my presence as soon as possible to allow them to plan to pass me safely. I also want the bike to appear as wide as possible.

USBcharger250@2xWe’ve already reviewed the front lights we’ve bought, and will do the same for the rear one – the plan in this post is simply to talk about where we’re putting them. At present, the scheme is to add one light at front and back.

We’ve chosen lights with built-in li-ion rechargeable batteries that are charged via USB cables. We’ve created a ‘charging station’ in a cabinet in the living room, right by the front door. This has the chargers for the bike batteries and also a four-port USB charger for the lights. That way, there’s no hunting around for cables – just come in from a ride and plug-in. And when we leave the house to go on a ride, we can just pick up the batteries and lights knowing they will be fully charged. In retrospect, I probably should have gone for a six-port USB charger, so that we could also use the charging station to charge a cellphone and backup battery – but I’m sure we’ll manage.

So, we have lights and they’re fully charged. Where should we put them?

On your head

A helmet-mounted light would seem to make sense, in that it points wherever you’re looking. From a conspicuity point of view, this also places the lights as high as possible. The problem is that it’s the worst possible place to put a front light. And the reason is: backscatter.

Whenever you have a light source that’s close to your line of vision, any moisture or dust in the air reflects it straight back into your eyes. The result is a kind of grey, low-contrast veil that partly obscures the view.

You can test this for yourself. Go out at night, preferably somewhere there’s no other significant light source. It also helps if it has just been raining. Use your bike light, held at waist level, to illuminate an object in the middle distance. Now move the light up next to your head. You’ll see a faint mist appear. You can still see the illuminated object, but not with the acuity you could before.

Backscatter is the reason underwater photographers place their lights on arms, to move them away from the camera. It’s why the fog lights on your car are mounted low down, significantly off-axis from your line of vision – and why, when you try using your full beams in fog, visibility gets worse, not better. It’s also the source of most of the ‘orb’ photos so beloved of a certain species of interweb whack-a-doodle. Basically, if you want the maximum sharpness, which is partly dependent on having good contrast, you want to move the light source well away from the lens, regardless of whether than lens is in your camera or your eye.

If you cycle somewhere where the air contains no appreciable moisture or dust, this may not be a problem. Same goes if you’re in a city with lots of light sources and are concerned only about conspicuity. But for us, cycling in the dark countryside in Europe, with its ever-moist air, a helmet-mounted front light is a poor choice. (A back light is a different matter.)

The offside rule

So, we’ve mounted our additional lights on the bike. I believe there are rules in many places that lights must be mounted on the bike’s centreline or on the offside (ie, towards the centre of the road). And this makes a lot of sense in terms of letting other road users know how much space you’re taking up.

Cateye Volt 200

Cateye Volt 200

At the front, I’ve simply added a light on the handlebars, as close as possible to the left grip. The models we’ve chosen (both Cateye) unclip easily when parking the bike. They are also positioned conveniently close to the control panel for the e-bike features. This has a USB power outlet, so we can run the lights from the bikes’ main batteries. (I then won’t be able to power my iPhone, though. I never thought the day would come when I’d consider mounting a USB hub on a bicycle. 😉 ) Being on the bars also places the light higher than the one supplied with the bike. I have the Axa Pico angled very slightly down to illuminate the ground immediately in front of the bike. The Cateye, with its more powerful beam, lights up the road further along, although I’ve been careful not to have it pointing too high, with all the problems that can cause for oncoming motorists (the 700 in particualr really is bright on full power).

At the back, the Smart Lunar R2 was chosen partly because of its clip. This allows me to clip it to the back of a pannier, or move it to the mount supplied with it, which I’ve put on the DoggyHut. Either way, it’s on the offside, creating (in concert with the built-in light) a visually wider target. If I’m not hauling either a pannier or DoggyHut (unlikely), it’ll clip to a jacket, saddle bag … well, something.

The light can be used in steady or flash modes – and yes, I know there’s a controversy lurking there – I’ll deal with that properly another time. Here, I’ll just say that I think a combination of one steady and one flashing light is a good mix from a conspicuity viewpoint.

And so, in a nutshell – two lights each at front and back, with the lights placed as far apart as is practicable to present the largest-possible visual target (although maybe that’s not the best choice of word). And having two lights at the front means they can be pointed at slightly different parts of the road for maximum coverage & situational awareness.

That’s not the end of the story, of course. Conspicuity also depends on reflectivity, but that’s for another day.


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