How Bright Does a Bike Light Need To Be?
By Graham Peaden
How do you choose a bike light?
The brightness of a light is measured in Lumens. To give a comparison figure a car light produces about 700 lumens. Bike lights can vary from say 15 to 1500 lumens or more depending on the light. So how do you choose the right light for your bike?
On Road Cycling
If a bike is used solely for on road cycling then the light does not need to be as bright as a bike that is used for off road cycling. Even so when riding on road you still need to be seen by all of the traffic that there is about. There can also be sections of a road which are not lit by street lights. All of these factors need to be borne in mind when selecting a bike light. For on road cycling where you might be just commuting from home to work you probably don't need a front light to be brighter than 200 lumens. If there are dark stretches along the route then maybe 400 lumens might be needed. A rear light would need a lot fewer lumens as that is more about making sure that you are seen by traffic rather than illuminating your path.
Off Road Cycling
For off road cycling a much brighter light would be needed in order to be able to see what hazards there are ahead. It is likely that there won't be any other form of lighting in the place where you are cycling and so the light that you have must provide all of the light to safely travel off road. Here you want to consider a light with a minimum of 600 Lumens but you might be safer going for 800 to 1000 lumens.
A compromise light might be one of the Lezyne lights which has a powerful "overdrive" facility which provides a very bright light for off road but has normal 200 to 600 for ordinary on road use. Such a light might be the Lezyne 600 LX Macro drive which can produce 15 - 600 Lumens for ordinary use and 900 Lumens for off road use.
Other aspects to consider in buying a bike light
2) Side on Visibility.
Another factor when travelling on roads is side on visibility. It is all well and good being very visible at the front and back but at junctions you need to be seen by traffic from the side.
Many bike lights have a "leakage" factor built in so that the light emits some light to the side of the light. It is even possible to buy lights that are specifically designed to shine to the side of the bike.
Alternatively you could rely on good bright reflective strips or lights that attach to the spokes of the bike to give high side on visibility.
3) Connecting to your bike.
Another factor to be considered is how easy or difficult it is to connect the light to a bike. Some lights have rigid fixings and some have very flexible ones. All of them will have to stand some vibration from the roads or tracks where the bike is travelling. This is especially true of off road riding. How easy or otherwise would it be to connect the light in the dark and in the cold, when you may be wearing gloves?
4) Battery Charge time.
Depending on the light that you get you will also need to consider how long it takes to charge up. If you are using a bike for a regular commute then it might be easy to charge the bike light whilst at work. Some lights can be charged in a couple of hours, but some take as long as 5 hours to charge.
5) Discharge time.
A bike light is only as good as the time that it is switched on so another factor to consider is how long the battery is going to last. It needs to last as long as the journey that you are doing, or you will need to carry a spare light or battery depending on your light.
6) How strong / robust is the light constructed?
A bike light needs to be strong and robust. Even if it is just for commuting it is quite possible for the bike to slip over in cold slippery weather and for the light to therefore impact on the ground. It is also possible that it might get dropped when putting a light on or taking it off a bike.
7) Waterproof or watertight construction.
A bike light is going to get wet whether it is used for commuting or for riding off road. Therefore you need to consider how waterproof a light is.
Ultimately the choice of light is determined by the use that you need to put it to, but it is good to get a light, or two, which suits the particular use that you need it for.
For further information see [http://www.goodbikeadvice.com/bike-lights/] where there is lots of useful advice about bike products.