Choosing a bike light
Winter is approaching in the northern hemisphere and nights are getting longer again. If you are out cycling, one of the most important bits of kit you need to stay visible on the roads are lights!
There is a huge range of bicycle lights to choose from in the market, so how do you go about finding the right set of lights? Below are a few things that we look out for.
The exact brightness of lights you will need depends on the roads that you ride. If you only cycle on well-lit roads, a front light producing around 250 lumens should be sufficient; on dimly-lit roads, consider something around 500-700 lumens to illuminate the path ahead. To avoid blinding oncoming road users, we prefer lights that have a shaped beam that reduces the amount of light projected upwards (if these are not available, point the front light a few degrees downwards at the road ahead). Not only is this more considerate, it is also safer for everyone.
Rear lights are gradually getting brighter as well in recent years, although anything with around 70-100 lumens should be bright enough for night time cycling. If your light has a brighter setting, reserve these modes for use as daytime running lights to avoid blinding other road users.
If you plan on riding off-road or in unlit areas, a much brighter front light with a wider lighting pattern may be required to properly illuminate the path in front of you. In such cases, make sure you dim your lights when you get back onto roads to avoid affecting other road users.
The main purpose of bicycle lights in well-lit urban areas is for you to be seen by other road users. This means that lights need to grab the attention of other road users, and then keep their attention while you are in their vicinity.
Since flashing lights are not used by most road traffic, having a set of lights that flash is a good way to identify yourself as a cyclist. However, we would advise against using overly bright flashes or crazy flashing patterns. While great at grabbing attention initially, it is incredibly difficult to focus on a mass of flashing lights without becoming dazzled. Many road users will simply choose to look away instead, which is definitely not the desired effect.
For our own use, we put a set of secondary lights onto a pulsed flash pattern, and have our main lights set to emit a steady beam so others can more easily focus on our position. Some lights with multiple LEDs can combine the two functions into one unit, which is a useful way to simplify the setup.
Depending on your specific riding conditions, you will need to experiment to find the best lighting setup for yourself.
Aside from brightness, viewing angle is also very important. All lights will be clearly visible when viewed directly from the front/rear, but their casings might obstruct the light when viewed from an angle, making them almost invisible to road users approaching from the side (for example, at junctions).
When choosing a light, look at them from different angles to check their sideways visibility, and look for designs with rounded light covers, sideways mounted LEDs or transparent strips for improved viewing angles.
Lights that run out of power are just deadweight. Make sure your lights will last well past the duration of your entire ride. Modern lights often use lithium ion batteries that can supply high powered lights with hours of battery life.
One characteristic of lithium ion battery-powered lights is that they do not dim (much) as their charge runs down. On the plus side, this means the lights stay useful for longer; on the flip side, this means you don't get any warning before the light suddenly cuts out. We therefore suggest choosing lights with a battery level indicator.
An alternative option is to go for dynamo powered lights, although this is a much more expensive solution. If you don't want to ever worry about battery life, this is something that you may wish to consider.
Other things to consider
Lights get knocked and dropped, so make sure you choose something that is sufficiently tough to handle everyday use. If you cycle enough, you will eventually come across rain, and that's exactly when you don't want your lights to cut out, so make sure whichever light you choose has good water resistance too.
Good lights are also a prime target for thieves (annoying $@#%!!). Make sure you select lights that can be easily removed so you can take them with you when leaving your bike.
Any light is better than no lights, so even if you cannot find a perfect set, make sure you have something that you can use in the meantime.