Light up the night: a guide to cycling in the dark

Lights are a legal and practical necessity whenever you’re cycling between the hours of sunset and sunrise. You must have: white front light; red rear light; red rear reflector; amber pedal reflectors. It’s not quite that simple – see our complete guide – but such a setup should satisfy safety concerns and the police.

If you’re an habitual night-time cyclist, the approaching end of British Summer Time is your final cue to locate your lights and test that they still work.

If you’re not yet a nightrider, rest assured that you’ll often be given a wider berth by drivers at night than you would during the day. Your white front and red rear lights remind them that you too are traffic.

Be prepared

You need lights whenever you might find yourself riding in the dark, not just when you plan to. Maybe a meeting at work runs over. Maybe you get a mechanical problem and it takes a while to sort out.

If you have dynamo lights, bolted to your bike and powered by a hub generator, then you’re more ‘ever ready’ than any battery-lit cyclist. You can’t forget your lights and they won’t run flat. Only a disconnected cable or vandalism is likely to stop them working, since modern LEDs last much, much longer than the incandescent bulbs of old.

Most battery lights are quick-release ones that attach to the handlebar and seatpost. Since you’ll remove them regularly, there’s a risk that you’ll forget them. Store them somewhere you won’t fail to take them with you. Alternatively, fit bolt-on battery lights to the fork crown and the rear of a pannier rack.

Whichever type of battery lights you choose, make sure the headlamp at least is rechargeable. It’s worth carrying a couple of be-seen lights as a backup in case your main lights fail. For the front backup, consider a small head torch; it’s great when making unexpected repairs in the dark.

There are some routes that you might use in daylight that are best avoided at night

Being seen

If you’re using battery lights, be aware of their runtimes and charge them regularly. The output of rechargeable lights can drop off rapidly as the charge remaining depletes. If your bike lacks mudguards, dirty water and road grime can also compromise light output.

Flashing lights draw the eye more than steady lights. Unlike most other road users, cyclists are legally permitted to use flashers. As a result, the flashing red rear light has come to be associated with cyclists. The problem with flashers is that they make it harder for drivers to judge your distance or track your movement.

If you’re riding anywhere without streetlights, use a steady rear light as well as or instead of a flasher, or set the light to pulse mode (if available) so it never goes dark. Flashing front lights are of minimal use to see where you’re going and bright ones can distract other road users, so a steady lamp is always better up front.

Reflective items also help pinpoint your presence. Pedal reflectors and reflective ankle bands are especially good as the up-down motion is unique to cyclists.

Lighting your way

How much light you need to see where you’re going will depend on where you ride. If you ride solely under streetlights, you don’t need much of a beam at all. If you ride on unlit roads, you’ll need a strong beam that illuminates the road at least 15 metres ahead.

That’s determined by how well the light is focused as well as how powerful it is, so it’s difficult to be prescriptive, but around 300-800 lumens should be enough for a steady pace on unlit roads. Off road, you’ll need more light – probably 1,000 lumens or more – in a wider spread.

Adjust your speed to suit your front light’s beam. You must be able to stop within the distance you can see ahead. At 15mph, you may need 10 metres to stop – and you can double that or more if it’s raining or you’re tired. It’s very easy to hit potholes in the dark.

For that reason, stick to familiar routes at night as far as possible. That way you’ll know where the hazards are.

There are some routes that you might use in daylight that are best avoided at night – that unlit cycle track, perhaps, or that inner city underpass. This is a pressing issue for women in particular, which is why Cycling UK started running glow rides each autumn to draw attention to it; see pages 14-15 for more.

Dazzled!

Oncoming car headlights on full beam can blind you. The driver is legally obliged to dip the headlights but might not. If you see a car with full-beam lights approaching, don’t look directly at it.

Slow down and dip your head so you’re looking just in front of your front wheel. If you can do it safely, turning your handlebar side to side will wiggle your front light and might remind the driver to dip.

Some cycle lights are more than capable of dazzling drivers. Resist the temptation to give them a taste of their own medicine. Apart from being annoying and dangerous, it’s against the law.

The Highway Code (Rule 114) says: “You MUST NOT use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders.”

If you use a high-power front light intended for mountain biking at night, toggle it down to a lower setting whenever you see other road users.

How bright is right?

Cycle light output is usually measured in lumens. (German manufacturers use lux; 1 lux = 1 lumen per square metre.) How many lumens you’ll need for your headlamp will depend on where you ride.

Under streetlights: 50+ lumens

In urban areas the role of your lights is to get you noticed rather than light your way. Small, bright lights without a defined beam will suffice.

Example: Lezyne KTV Drive/KTV Drive+ Light Set, £47.

Unlit lanes: 300+ lumens

For unlit rural roads and badly surfaced, badly lit urban roads, you’ll need a front lamp with a beam to light your way and pick out your path. Around 300-800 lumens should suffice, depending on your speed.

Example: CatEye AMPP 500S/ViZ 150 Bike Light Set, £64.99.

Off-road trails: 1,000+ lumens

On trails you need lots of light and a wide spread, not just a focused beam. But for riding on roads as well, the facility to switch instantly between ‘full beam’ and ‘dipped’ is indispensable.

Example: Ravemen PR2000, £149.99.