A Guide To Bicycle Lights | Cycling UK

The autumn and winter period in the UK is never the easiest time for bicycle commuters who invariably have to contend with colder temperatures, increased rain and longer hours of darkness. Keeping warm and dry is hard enough, but keeping up with adequate lighting requires a proper test and review every year. In addition, the hostile environment we expect our lights to operate in is tough enough for any electrical item, so don't expect too much from them.

Batteries

The days of disposable battery bike lights are now nearly gone….there are a few cheap versions still available but they’re really not worth it. The one exception to this is the tiny blinky lights that can be used as a back-up to your main system. These lights run on watch-type batteries (CR2032 are the most common size), and they can run for many hundreds of hours with acceptable levels of light for such tiny units.

The vast majority of bike lights on sale now contain lithium ion/polymer batteries similar to those powering our mobile phones. These batteries can be made small enough and light enough to hold enough charge to give acceptably long burn times for most riders and can be easily charged by USB cable from the computer on your desk. Previously available rechargeable batteries were the NiCad or NiMH types which looked like the batteries of old but could be recharged; the problem with these being that if not used they would self-discharge quite quickly.

A note of caution with lithium ion batteries, however. When the winter is over and your lights are put away for the summer, you should take note of the manufacturer's instructions for what to do to preserve battery life. Most of them will have special procedures for you to 'tell' the light that you are shutting it down for more than a month. This puts the battery in a different state - one that will enable it to recharge properly when next winter inevitably arrives. It can be an expensive mistake if you don't follow the instructions (which will be buried somewhere in the paperwork!) as it is usually a condition of the warranty.

Front lights

Front lights need to be chosen carefully and take into account the sort of night time riding you're going to be doing. If you're only going to ride in urban areas, your main consideration is to 'be seen' by other road users. If you're going to be riding on unlit roads and paths then you will want a light that will help you to 'see' - you'll want a unit that is bright enough to show the potholes on the roads before your wheel disappears into one. You'll also want to see corners before you reach them!

With advances in rechargeable lithium batteries and LED technology, it is now possible for manufacturers to produce extremely high powered lights. For urban use, these are not necessary and are likely to dangerously dazzle other road users (which is not legal!). They are also likely to be heavier than a 'commuter' light and cost proportionally more. A front light producing up to 500-700 lumens with a flashing mode is ample for most urban riders, although having more than one light as back-up is also a good idea. Rechargeable Lithium batteries don't slowly fade when they run out of juice - they just stop. So you don't get much warning.