It’s great to be able to see exactly where you’re going. It may seem obvious, but a bright front light – say, of 200 lumens in the city or 600 off road – will allow you to spot pot holes, broken glass, and maybe even an abandoned £20 note.
Front Light: A flashing light needs to be at least ‘4 candelas’, which equals roughly 50 lumens, which is fairly modest. A bike light that can put out a steady light should be marked as conforming to BS6102/3 or an equivalent EC standard (read more about this on Cycling UK). Lights from reputable brands such as Cateye, Lezyne, Exposure, and Moon meet this standard.
Rear Light: Rear lights in general emit fewer lumens than front lights, but if they are flashing then they must also emit at least 4 candelas. Again, lights from reputable brands such as Cateye, Lezyne, Exposure, and Moon meet this standard.
For more guidance on how bright your cycle lights should be, take a look at our blog: What Bicycle Lights Do I Need?
Legally speaking, it’s somewhat open to interpretation. The Road Vehicles Lighting Regulations say it is an offence for vehicles (any vehicles) to cause “undue dazzle or discomfort to other persons using the road”.
Morally speaking, it’s nice to be nice, and it’s also nice to not cause other people to have accidents. Nobody likes to be blinded by someone else’s lights. When riding on shared paths in particular, dip your lights down instead of pointing 1,000 lumens straight at people’s faces (including other cyclists.)
If you want to geek out on the brightness of bicycle lights, here’s a good article by Chris Juden called ‘Dazzling Bike Lights’.
Dynamo powered lights are lights powered by a dynamo hub built int o the front wheel of your bike. If you buy a bike by a brand like Kalkhoff, it will come fitted with a Dynamo light. These are legal – even if they don’t have the ‘standlight’ technology which means the light doesn’t immediately go off when you stop riding e.g. at traffic lights. The benefit of a dynamo light is that you never need to replace the batteries or recharge it.
