Your guide to the best front lights for cycling + beam comparison engine

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When the clocks go back and the nights draw in, you need to make sure you've got a set of lights on your bike. It's the law in the UK to run them after dark, and they're a major safety aid about town as well as letting you see where you're going in the dark lanes.

If you're in the market for some bike lights there's a bewildering array of lights out there to choose from, ranging from a few quid to nearly a grand, so what's the best bet for your riding? To help you choose here's road.cc's quick guide to the technology and the options available for your front light.

Check out our beam comparison engine

Our beam test comparison data contains beam shots and data for over 40 of this year's lights, so you can directly compare one with another. It's at the bottom of this page.

It's LEDs or LEDs these days

A few years ago you had a choice of different bulb options to consider, but LED lights have improved to such an extent – and come down in price too – that there really isn't a choice any more. LEDs tick all the boxes for a bike light. They're tiny, they cost tuppence to make, they last for ever, they're rugged, they run fairly cool and they're easy on the juice. No wonder that everyone's using them these days. There's LEDs and there's LEDs – the bulbs in a cheap flasher that look like the ones out of your old 100-in-1 science set are a long way removed from the high-spec emitters in top-dollar off-road lamps. Outputs have shot up in the last year or two as well, with the brightest lights claiming outputs of several thousand lumens, more than a car headlight. More general purpose lights range from 50 to about 500 lumens, with basic commuter lights and emergency lights weaker still; they're mostly to be seen by, though, not to see with.

Setting the standard.

Technically, all bike lights must be fitted to comply with the Road Vehicle Lighting Regulations (RVLR). For the record, here's what those regs say...

Front Lamp
One is required, showing a white light, positioned centrally or offside, up to 1500mm from the ground, aligned towards and visible from the front. If capable of emitting a steady light it must be marked as conforming to BS6102/3 or an equivalent EC standard. If capable of emitting only a flashing light, it must emit at least 4 candela.

Rear Lamp
One is required, to show a red light, positioned centrally or offside, between 350mm and 1500mm from the ground, at or near the rear, aligned towards and visible from behind. If capable of emitting a steady light it must be marked as conforming to BS3648, or BS6102/3, or an equivalent EC standard. If capable of emitting only a flashing light, it must emit at least 4 candela.

You also need a rear reflector and four pedal reflectors to fully comply with the RVLR.

In practice, not all bike lights are kitemarked. The specification for lights dates back to 1986 and is designed to apply to lights with filament bulbs. That doesn't mean that LED lights can't meet the requirements – many do – but lots of them aren't specifically tested for the ageing Brititsh standard, especially those that are for the worldwide market. Since the RVLR was amended to allow cyclists to fit flashing LEDs we've heard very little about cyclists being stopped for having non-compliant lights.

Choosing a light: things to consider

What am I going to use the light for?
Are you going to be pootling down to the shops, or do you detour through the woods on the way home? You need to consider how much light you need, and where you need it to be put. Brighter is often better, but look for lights with good side visibility if you're riding a lot in town: side visibility is very imprtant when coming out of a junction.

If you're solely riding on the road, look for a light with a beam pattern that's not going to dazzle oncoming traffic. Narrow beams and German-style cutoff beams (designed to comply with German road lighting regulations, where 95% of the available light must be directed downwards) are the ones to look out for. If you're mixing up your road riding with paths and singletrack, a light with a wide beam that has lower-power modes for use in traffic may be the one to go for.

If you're going to be doing a lot of swapping between bikes, consider how easy that's going to be. Are the mounts quick release? Are there lots of wires to deal with?

How regularly will I use the light, and how long per day?
If your commute is an hour and your light gives out after 50 minutes then you're in trouble. If it has a proprietary charger rather than batteries or a USB charge option, then it needs to last to where you're going and back again. Think about when you'll recharge the light and how long that will take.

Many lights have low-power options that will extend battery life, so it's important to work out if these will give you enough output for certain sections of your ride. Many lights have fuel gauge displays to let you know the state of the battery, these can be very useful if you ride regularly and aren't good at remembering to charge your lights.

What conditions will I use the light in?
If you're riding every day, come what may, your lights will take a beating. They're very exposed to rain and spray at the front of your bike. Generally the more expensive lights are better constructed with more effective seals, so spend as much as you can afford. If you think you might break your lights from using them in all conditions, check what the warranty is like.

The gamut of glare

Okay, so you've got to buy some lights. What kind of lights do you need? here's a quick run down of the basic types you can get your hands on, and who they're aimed at.

Emergency lights

small enough to leave in your bag for when you need them, emergency lights normally attach with a stretchy band to the bars or frame and are powered by button cells. They don't put out a great deal of light but as an get-you-home solution if you get caught out or your main lights fail, they're a lot better than nothing.
Try: Cateye Loop Lights, Electron Backupz, Knog Frog

Small flashers

The next step up is a bar/frame-mounted flasher. Most of these are capable of putting out a steady beam too. They're a bit bigger and sturdier than an emergency light, and they generally take AAA batteries which last for ages. You can pick them up cheap so they can be better value all round – in terms of buying and running – than emergency lights.

Torches

There's lots and lots of choice when it comes to torch-style front lights. Powered either by AA/AAA cells or – more commonly now – a rechargeable battery pack, they put out a bit more light: if your riding takes you anywhere you need to see – rather than just be seen – you'll need at least one of these. Often manufacturers will bundle a torch-style front light with a rear flasher, seeing to both ends of your bike and scoring you a bit of a discount in the process. Rechargeable units sometimes come with a mains adaptor but USB chargers are becoming increasingly common, allowing you to juice up your light at your desk. The brightest torch-style lights now kick out over 1,000 lumens, which is more than you'll ever need for road riding, but on lower settings the best ones will run all night.

Rechargeable systems

These tend to be characterised by a separate battery pack attached to a smaller head unit that's a lot more powerful than a standard torch. They start at around £20 for a CREE-powered ebay light but you can pay the best part of a grand for the really high end stuff. If you want to go out regularly and train after dark on the lanes, or venture off-road, then a rechargeable set may be your best bet.

Dynamo lights

If you want your lights to be a permanent fixture and never worry about batteries then you can't do better than a dynamo. Hub dynamos are the pick for low maintenance and decent output; most will supply 2.4-3W which is plenty for a bright light front and rear. Pick a system that stores some of the energy from the dynamo so you don't go dark when you're stopped at the traffic lights. Many riders leave their dynamo lights on for daylight running too, as they draw very little energy from the bike.

Head torches

Fitting a light to your helmet means you can point the beam where you want it, making the light a lot more useful. Some of the smaller rechargeable systems come with a helmet mount, or you could go for a more general use headband-type light and ziptie it on. Bear in mind that you should also have a fixed light on your bike if you want to comply with the law.

The light comparator

If you have a nice big screen you can click here for the widescreen version (1400x1000px)

About the beam comparison engine

We've collected lots of beam data so you can compare and contrast the different lights. Light manufacturers use a number of different metrics to describe light output. We've used lux here, but measured at a number of points across the width of the beam. That gives an indication of the brightness of the beam at the centre, the amount of peripheral light and the throw of the beam. We think that's the most useful measurement to directly compare. Specifically, we measured the lux value of the beam at two metres distance, in 10cm increments from the centre of the beam to 1m from the centre, giving eleven readings.

We've also included data on the shape of the beam. In previous years we've struggled to get a meaningful shape for many lights using a fixed position, so this year we've been a bit more subjective. The lights were positioned such that the shape of the beam was most noticeable, then readings taken from 0° round to 180° in 30° increments. Then the numbers were normalised for all lights, to a maximum value of 10. That gives an indication of the beam shape.

Most of the lights we tested still had a more-or-less round beam.  For riding on the road a squared-off beam has advantages. You're not wasting your battery lighting up the tree canopy, and you're less likely to dazzle oncoming traffic. Such beams are widely used in Europe, and in Germany they're the only lights legal for use on the road.

To get a good idea of what each beam looks like, we set up a bike on a rig so that we could photograph the beams of all the different lights in a comparable way. Each of the beam shots you can see above was taken using the same settings on the camera: 28mm (effective 45mm), shooting for 2s at f22 on ISO3200. If you fancy doing some of your own. So as much as they can be, they're directly comparable to one another. If one looks brighter than another, that's because it was. Skardy the Altura-Night-Vision-sporting model is at 10m (the cones are 2m apart) and the car is 20m away.

A word about logs

The graph displaying the beam data uses a logarithmic scale to display the output of the lights. If you understand or care about such things, here's why:

Firstly, light beams follow an inverse square law regarding the strength of the light at increasing distance, because they're illuminating a two-dimensional plane. So at twice the distance, the light beam is spread over four times the area. Consequently, a light that is measured as twice as bright at its centre won't let you see twice as far. The logarithmic scale produces a more realistic visual comparison because of this.

Secondly, the variations in the amount of peripheral light, though much smaller than the variations in the centre, make a big difference to how much peripheral vision you get. The logarithmic scale amplifies these differences relative to the centre of the beam, so it's easier to see which unit is putting out more light at the sides.