Seeing the lights 0

Light illuminating a fallen tree

Lights: quite useful at night.

It doesn’t seem all that long ago when my winter lights were packed away and I was enjoying riding until quite late in to the evening. And yet the nights are drawing in fast and already I’ve had to break the lights out. For the next few months, if you want to ride it will be difficult to avoid having lights on your bike. But which lights should you get? There are so many to choose from, ranging from a few pounds up to several hundred; how much you need to spend depends on what you want the lights for.

The simple answer is ‘to see where I’m going’, but like so many things in cycling these days the real answer is a bit more complicated and usually starts with ‘well, that depends…’

To see or to be seen

The first thing to realise is that lights perform two functions; so you can see the road, obstacles and hazards, and so that other road users can see you. The second of these is arguable the more important, and fortunately the cheaper of the two to deal with. I think it is always worth making sure you have enough reflective clothing on to look like a Christmas tee when headlights shine on you, but a light can really help drivers identify you. A small, flashing red light facing rearwards is a great idea. Lots of companies do cheap flashing lights that use super-bright LEDs that can be easily attached and removed from your seatpost. A flashing light helps motorists see you, and also to show that you’re a cyclist near by and not the steady back light of a motorcycle further away. Given how cheap these lights are, I always ride with two of them just to make sure I have one that works. You can put a similar white light on the front of your bike. As this is a light to be seen by you can also have this flashing. Flashing lights are easily identifiable and have the added bonus of helping batteries last longer.

My favourite lights in this category are the Moon Lights Comets and the Knog Frog. I keep one of each on my bikes throughout the winter.

Lighting the path

Using lights to be able to see is a trickier one to buy for. The simple solution is to buy the most expensive lights from Hope or Exposure and ride everywhere as if it were daylight. But at over £400 a light this isn’t necessarily the best option for most people. There are three things, beyond budget, that you need to consider when buying lights: throw, spread and burn time. There are other nice-to-have features like programmable settings, variable intensity and integrated or separate batteries, but these should only be considered once you’ve decided which lights best suit your needs.


This is how far ahead of you the light effectively illuminates the road and other objects. It is generally considered by road safety experts that it takes around 2 1/2 seconds for a cyclist to identify a danger and stop in time to avoid it. In dark or wet conditions this time is increased. We also don’t want to be on the edge of our seats ready to pounce at every dark shadow so perhaps having 5 seconds of illumination gives us ample time to cycle safely and avoid all obstacles.

In a city, or well lit suburban area this illumination is kindly provided by the street lights and other lighting. In general all we need our light to do is keep us safe for brief periods where lights are out or as we traverse poorly lit areas. Also, generally in built-up areas we tend to cycle slower so our lighting needs are not that great. But, in a rural area, or off-road it is a different matter. The chart below shows us just how much distance a light needs to be effective over at a variety of speeds. This is for just 3 seconds of illumination, the minimum we need. It isn’t all that difficult to get to 30km/h either on- or off-road and for that a light has to be effective at over 25m. Going downhill on the road you can easily each 50km/h and will need 40m of light. And this is just for 3 seconds of visibility, which makes for surprisingly tense riding. Increase it to a comfortable 5 seconds and you can see you need some pretty powerful lights if you want to get out and train during the winter.

Visibility distances required for 3 seconds visibility at various speeds


It’s all very well and good lighting up 3 seconds ahead of you, but it is important what exactly gets illuminated. You need to be able to clearly identify any risks and to see enough safe room ahead of you to avoid the risk. On the road, especially now, the biggest risk is potholes, followed by other road users such as other cyclists and pedestrians. Potholes in particular need a very direct light. The road surface itself needs lighting well enough to see what you’re cycling in to, but not such a direct light that you can’t see the kerb and people on the road-side. Off-road there are more dangers around us, branches sticking out for example. For this, we want a less direct beam and a wider spread of light. For any given light you’ll either have a direct beam, or a spread light. Some manufacturers have a lens system that allows you to change the focus of the light, this is more true of milt-purpose sports lights than it is of bike specific lights. However, if you’re prepared to invest in a top-of-the-range light you’re likely to get a dual beam system where one light gives you direct light and the other a good spread. Being able to change the way your light performs can be a good solution for cyclists who ride both on- and off-road and the one light can do both jobs well. For the more budget conscious amongst us there may need to be a little compromise.


It is easy to modify your riding to be able to ride safely within the throw and spread of your lights. However, it is less easy to ride safely once the light goes out! This, perhaps is the most important consideration: how long with the light burn for? And what happens when battery power starts to wane?

Some, usually cheaper, lights burn just as well as more expensive ones but once the battery starts to drain they go from really bright to off in a matter of minutes. A more fully featured light may well give you adequate warning, and also have a ‘get me home’ mode where the output is reduced to a safe minimum to allow you to limp home before the light fails completely. The more expensive the light, the more impressive the battery. This can mean smaller for the same power, or just longer lasting. And this is the next decision. Do you go for a massive battery perhaps with capacity you don’t need? Or a smaller battery and risk running out of power? This will depend a lot on how long your rides are, and for how much of the ride you need full illumination. I’d always rather carry more battery and not run out. Consider the weight as extra training. Also, remember that batteries do decrease in performance with age, you your 4 hour battery might only give you 2 hours after a couple of years. Some lights have internal battery packs, others have external ones. Internal ones are neat and make the lights easy to fix on to the bike. External ones mean that it is possible to carry a spare battery. Although, an external batter can be larger so often by having an external pack you don’t need the spare.

Lights and the law

It’s not quite as easy to obey the light laws as you’d think!

Firstly, after sundown you need to have a rear red reflector (easy enough) and two yellow reflectors on each pedal (not quite so easy if you use a clipless pedal system). Secondly, you need an approved red rear and whit front light. Your lights have to conform to BS6102 Part 3 and be marked accordingly. But, as most lights are made for a global market many very excellent lights do not have the British Standard marked on them even though they may well reach or exceed the standards required.

If your lights flash, they don’t need to be BS approved, unless they have a steady mode too which in practice means they’ll need to be approved. It is likely that any light you buy today will be good enough to be safe, but if you were unfortunate enough to be in an accident expect a lawyer to make a big deal over the BS conformity of your lights. Also, don’t be fooled by the EC mark on the lights, this just means they’re electorally safe and non-toxic and doesn’t have a legal baring on their effectiveness.

Lastly, to be legal, the lights have to be fixed securely to your bike, and not to you, or dangling. Once you have your approved lights fixed securely your bike there is nothing stopping you from dangling yourself in as many unapproved lights as you like, as ling as they’re not a danger to other road users.

Which lights do I need?

Choosing the right light means deciding what you need the lights for. There is no excuse not to have small flashing lights so you can be seen. They are cheap, small and easy to fit. Then, decide what your lights need to illuminate. If you’re a city commuter, or just need to cycle slowly home in the evening then you can look for a cheaper light, possibly powered by standard batteries. Cateye seem to have this market well wrapped up and do a variety of inexpensive and powerful lights that are ideal for the job. Most have a mounting bracket for the bike on to which you clip the lights allowing you to remove the lights to keep them safe. Lezyne do some very nice lights too, often powered by an internal battery that you can charge via USB, this means you can easily charge them at work using your computer so don’t need to carry a charger around with you. These lights are usually a bit more expensive but generally look very stylish if that’s important to you.

If you want lights so you can keep riding hard and training all through the winter then you’re not likely to get all that much change from £200, more if you want the fully-featured top-of-the-range lights. You can find no shortage of lights on Amazon from little known companies that seem bright and good value. But, be warned, often the batteries are not up to scratch and have short lives. The units themselves are also not always particularly robust and don’t stand up to the rigours of hard winter riding. But, at less than 1/4 the price you can afford to replace them 3 times as often and still save money. If you want reliability, features and performance then two companies stand out from the rest: Hope and Exposure. Both make excellent lights but be prepared to pay for the excellence. To my mind, if it means I can ride safely all winter then the cost is worth it.


Manufacturers usually let you know how powerful their lights are by using lumens. A lumen is a measurable ‘amount’ of light and is the standard way of measuring lights these days. But, so often you’re not comparing like with like which makes it difficult to pick the right light.

Firstly, it might be that the 1,000 lumens rated by your light is on a full charge, but 20 minutes of battery use and the light dips to 600 lumens. A different light, rated at only 800 lumens might seem worse but if the light remains at 800 lumens for 2 hours it may well be the better option.

Secondly, it depends on where those lumens go. 1,00 lumens are great if they all light your way, but if 1/3 of the light is spilling round the edges and lighting things to your side then, again, it may not be the best light.

However, you can use a few rules of thumb to get you started, but it is important to get good advice and to test a light out before buying. Obviously, this isn’t always practical as your local bike shop may be too well lit, but go later in the afternoon and perhaps they’ll have a darker area outside you can use to check the light. However, you don’t need to test the light yourself. Contact your local bike club, or ask your cycling mates about their light experiences. You can turn up to the start of a club ride and see several lights in action.

Rules of thumb

Up to 100 lumens Lights to be seen by
200 to 400 lumens Commuting lights
400 to 800 lumens Just about good enough to train with, or for emergencies
800 lumens and up Lights suitable for hard winter riding

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