Unless you are only ever cycle during the day, in perfect conditions, you need lights for your bike. In many places, this will be a legal requirement, helping to promote both your safety and the safety of other road users and pedestrians. However, most cyclists would probably agree that any legal requirements should be considered a minimum, not a standard to follow.

One reason is that lighting technology is advancing far faster than the laws and regulations can. Older cyclists may remember when bike lights were an old-style incandescent bulb, with large reflectors, powered by the big D-cell batteries. In some jurisdictions even simple innovations like blinking LED lights are technically illegal, despite being better at increasing visibility, simply because the possibility of microprocessor-controlled lights had never been considered.

Today’s lights can offer a range of additional features that help to keep you safe, on- and off-road. But when you are thinking about what lights to get, it’s sensible to start with their core purpose: acting as lights.

Batteries and charging

Although the actual light is perhaps the most important part, it’s useless without power, so it’s worth spending a bit of time thinking about the battery.

While it’s still possible to get lights that use disposable batteries, these are becoming less common, and are usually low quality. Most lights now come with rechargeable batteries, using standard USB connections for charging. These have the benefit of being both more convenient and better for the environment (because you are recharging one battery, rather than generating lots of battery waste).

It’s important to look at battery size and think about likely use, so you can plan charging and re-charging if necessary. Although LEDs are far more powerful efficient than the old bulb lights, they are still relatively power hungry. This is especially true if they are particularly powerful, which might see battery life as short as a couple of hours. Typically, you can expect lights to offer six to eight hours of lighting in normal urban conditions, and you will have to assess how much you are likely to use them.

As a general rule, if you are bikepacking for a couple of nights or more it’s sensible to ensure you have some way of recharging, saving you from worrying about the charge lasting, or finding the lights fail at a critical moment. PedalCell offers an easy way to charge batteries, converting power from your cycling and delivering a steady current through its USB hub. This means you can charge your lights during the day, or even use PedalCell to charge them when in use.

Light power

The next thing you need to consider is the power of the lights. These are measured in lumens, while there is a precise and complex measurement of lumens, it’s probably easier to think of the old-fashioned candle power, and one lumen is roughly equivalent to the light of one candle. The more lumens, the brighter the light.

But that does not mean that brighter is better. The brightness you need will depend on where you are cycling and the specific light. Rear lights are much dimmer, sometimes as low as 5 lumens because their purpose is simply to highlight your presence. Front lights need to be brighter.

In urban environments, it’s likely that around 150-200 lumens is sufficient. At this level, they will stand out over urban lighting, but not run the risk of dazzling other road users. On roads in rural areas, brighter lights are necessary, possibly up to 1,000 lumens. These will help illuminate the road ahead in areas where there is no lighting.

If you are going off-road at night, then it’s likely the brighter, the better; a bright, wide-beam light helps ensure you have a clear view of what’s ahead. Chain Reaction Cycles’ LifeLine Pavo, for example, offers a wide, 2,000 lumens beam, although that brightness comes at a cost, the battery will last less than two hours.

Most lights will have variable settings, allowing you to adjust as needed. Some will even have daytime settings. Although this might seem unnecessary, most collisions occur during the day, and using lights in rain or foggy conditions helps improve visibility.

Other features

Of course, many lights can do a lot more, although the value of some features may be debatable. If you are cycling in different areas, it might be worth looking at lights with variable modes. One example of a well-featured light is the see.sense beam. A connected app, the gives the light lots of potential. Although some of the app’s features are novelties — it’s hard to see how a calorie estimate from a bike light can be accurate — it does offer some useful features.

Perhaps the most useful light-related feature is that it will automatically vary the lights according to activity. For example, responding to the ambient light, or brightening when it recognizes the stop-start of cycling in traffic.

Other lights go even further. A Garmin Varia rear light features a radar, connecting with a smartphone or their Edge bike computer to warn of vehicles approaching to the rear.

Just get a light!

The most important thing, though, is to get a light and use them.

While it’s possible to spend a lot of money on bike lights, the key things to focus on are the brightness and battery, so you can be confident the lights are on and visible. Once you have established what you need, you have a baseline and, from there, decide whether it’s worth spending the extra on additional features. Any good bike shop will be able to offer recommendations for a range of budgets.

And when you have your lights, make sure they are visible — it’s no good having a rear light if it’s tucked behind your panniers — and well-charged, then get into the habit of turning them on as part of your cycling routine. They are one of the simplest and easiest ways to make your cycling safer.