Which bike lights do I need, and what does the law require?

Lighting requirements for bicycles in Great Britain come from the Road Vehicles Lighting Regulations 1989 as amended, and they are more specific than most riders realise and easier to satisfy than people fear. Northern Ireland has its own broadly similar regulations. Everything beyond the legal minimum is a judgement about how visible you want to be, and there is a large gap between legal and visible.

Safety

Step by step

1. Know the four items the law requires at night.A white front lamp, a red rear lamp, a red rear reflector, and amber pedal reflectors front and rear on each pedal. These apply between sunset and sunrise when the cycle is on a road. A cycle without pedal reflectors — many clipless pedals have nowhere to fit them — is technically non-compliant, and enforcement in practice focuses on lamps.
2. Understand that flashing is allowed.Since 2005 the regulations permit a flashing lamp provided it flashes between roughly one and four times a second. Steady lights make your speed and position easier to judge; flashing lights catch the eye. Running one of each, front and rear, is a common and sensible approach.
3. Check the marking on lights you buy.Lamps that comply carry a British Standard or an equivalent European approval marking. Many powerful modern lights are not formally approved, which does not stop them being far more visible; if you want to be strictly compliant, run an approved light alongside them.
4. Choose front light output for the road you ride.On lit urban roads, a front light is mostly about being seen and a modest output is plenty. On unlit lanes and off-road you need to see the surface, which means a substantially brighter beam with a shaped cut-off so you are not blinding oncoming traffic and riders.
5. Aim the front light down.A bright light pointed straight ahead dazzles everyone coming towards you and lights the hedge rather than the road. Aim the hot spot at the road a few bike lengths ahead. German StVZO-approved lights have a shaped beam that does this by design.
6. Put the rear light where it can be seen.Seatpost or seatstay, unobstructed by a saddlebag, a rack or a jacket tail. Check it is still visible with your usual luggage on. A second rear light on the bag or helmet gives redundancy and a second, higher position.
7. Use reflectives on the moving parts.Reflective material on ankles, heels and pedals reads as a person on a bike from a long way off, because the up-and-down motion is unmistakeable and nothing else on the road does it. This is more effective than a large static reflective panel.
8. Keep them charged and carry a spare.USB lights die without much warning and cold weather shortens runtime considerably. Charge them on a schedule rather than when they get dim, and keep a tiny emergency light in the bag.
9. Fit a dynamo if you ride at night regularly.A hub dynamo with permanently fitted lights removes charging, removes theft of lights, and never goes flat. It costs more up front and is the right answer for a commuter or a tourer.

Tips

• Lights are also worth using in daylight in poor conditions. Bright rear lights in rain, fog and low winter sun measurably increase the distance at which drivers pick you out.
• A helmet-mounted light lets you look where you want to see — round a bend, at a road sign, at a driver waiting to pull out — which a bar-mounted light cannot do.
• Take lights off the bike when you park it in the street. They are a standard opportunist theft.
• Check the rear light is not pointing at the sky. Seatpost-mounted lights rotate slowly as the mount relaxes, and a light aimed upwards is invisible to the car behind.

Common mistakes

• Relying on high-visibility clothing instead of lights — Reflective and fluorescent materials only work when something shines on them. At night, on an unlit road, at a distance, they do far less than a lit lamp and they are not what the law requires.
• Running a very bright front light aimed level — It dazzles oncoming drivers and cyclists, who then cannot see you or anything else. Angle it down; visibility is about the beam shape, not just the number of lumens.
• Removing the rear reflector because a light is fitted — The reflector is separately required and it keeps working when the battery dies. It is the passive backup for exactly the failure that is most likely.

Questions people ask