If you plan on riding regularly through winter then you'll need to invest in top-notch lights - both front and rear.
While there's been something of a lumen war in recent years when it comes to front lights, with brands fighting to produce lights capable of illuminating a football field, rear lights have lagged behind a little.
That's beginning to change, however, and now there's a selection of seriously bright lights available from a wide range of manufacturers. We've picked out six of our favourites - but first, what makes a good rear light?
What to look for in a rear light
While a front light has a dual purpose in making you visible to oncoming traffic and, if it's bright enough, of course, lighting up the road in front of you, a rear light serves only to make you visible to traffic approaching from behind, and is perhaps even more important in ensuring drivers spot you in good time before safely overtaking.
While some front lights are capable of throwing out thousands of lumens - the new CatEye Volt pumps out a frankly absurb claimed 6,000 lumens - rear lights don't need anywhere need that output. In fact, the brightest rear light we've featured here has a maximum output of 100 lumens - and that's incredibly bright for a rear light.
It's not all about brightness, though, and it's also important to consider side illumination, particularly if you're riding in an urban area - can a driver approaching from anywhere but behind - pulling out of a side junction, for example - see you?
It's also worth considering the range of modes available. Generally speaking, the more modes on offer, the more versatile the light, and the more you can tune it according to the conditions you're riding in. It can also help to conserve the battery life by giving you the option to select the most suitable mode, rather than between a limited choice of constant and flashing, as is often the case with budget lights. Chances are, you'll often be able to make do with a medium-powered setting, saving the most powerful (and most hungry in terms of battery life) for only when it's needed.
The best lights will often offer a mode which combines a static LED with a flashing or pulsing LED, with the latter serving to attract a driver's attention and the former enabling them to safely gauge the distance between their vehicle and your bike. A number of manufacturers are also now marketing rear lights for daytime use (which sounds like a sensible move to us) and it's the brightest setting that will best serve you when the sun's shining into a motorist's eyes.
The majority of mid-range lights and above - and all of those featured here - are now USB rechargeable, which makes them easy to charge on the fly, whether you're at home or at work. That makes it far easier to top up the light's power, rather than having to guess when a non-rechargeable battery is going to run out, so there shouldn't be too many excuses to run out of juice.
The final thing to think about is mounting. It's always surprising, and incredibly frustrating, that many lights fall down by coming with a poorly-designed mount. Some are unnecessarily fiddly to use, and some down right don't work, but essentially what you're looking for is a mount which provides a secure hold, so the light won't be bouncing down the road when you hit the first pothole. Life's a lot easier if you have a conventional round seatpost, but you'll likely have to be more selective about what light you choose if you have an aero-profiled post.
Bontrager Flare R rear light
Bontrager pitch the Flare R as the first light designed for daylight visibility. Whether or not that's the case is besides the point, as what's obvious to us is that having a light on your bike during the day, as well as night, is a good thing. After all, if it's hammering down with rain or it's a particularly dingy winter's day, then it can be as good as dark, even at lunchtime - or, on the flip side, if a motorist's driving into direct sunlight, their vision can be equally obscured.
The result with the Flare R is a light which, as you'd expect, is incredibly bright and an excellent bit of kit whether you're riding during the day or at night. It offers a maximum output of 65 lumens and, while it's not the brightest light here in terms of outright lumen output, Bontrager say the optics have been optimised to offer 270 degrees of illumination and visibility from a distance of more than two kilometres. Our test certainly proved it to be very, very bright.
The Flare R offers two daytime modes (one steady, one flash) and two night-time modes (one steady, one flash), and there's also a battery save mode which kicks in when there's less than five per cent battery left, in order to try and get you home. The mount fits 22.2-35mm round seatposts without any problems, and the light attaches to the mount through a side-entry clip to provide a secure hold. It's trickier to get the mount to fit an aero seatpost, though.
Maximum output: 65 lumens
Exposure TraceR rear light
The Exposure TraceR is one of our favourite rear lights thanks to its lightweight and compact design, impressive output, excellent side-illumination and fuss-free mount.
The TraceR has a maximum output of 75 lumens and three brightness modes in all, in steady and pulsing beam patterns. The pulsing beam is particularly impressive. Rather than flashing, the light pulses, which ensures constant illumination. Clever features also include a fuel gauge, which lets you know how much battery life you have left.
The build quality is excellent, with a smart CNC-machined aluminium body, and the light securely snaps into the tool-free mount, which straps onto the seatpost using a tough silicone band. It's another light which is only really at home on round seatposts, though it can also be mounted under the saddle using Exposure's saddle rail bracket (sold separately).
The TraceR is also available as a set (£94.95) with the Trace front light, which shares a similar design (both lights weight just 35g each) and has a 110-lumen output, making this a powerful combo for commuting.
Maximum output: 75 lumens
Website: Exposure Lights
CatEye Rapid X3 rear light
The CatEye Rapid X3 is new for 2015/16 and doubles the output of the existing Rapid X2 from 50 lumens to a huge 100 lumens, making it the brightest light here.
It's another light marketed as suitable for both daytime and nighttime use, which is unsurprising given the brightness on offer, while there are six modes in all, described as: flashing, rapid, pulse, vibration, high and low.
The Rapid X3 has two rows of LEDs and the transparent unit ensures at least 180 degrees of visibility. CatEye has opted for a simple o-ring attachment and the mount is compatible with aero seatposts.
The CatEye Rapid X3 is the second-most expensive light here at £54.99, but if you don't need something quite so powerful then, as well as the 50-lumen Rapid X2 (£44.99), the collection also includes the 25-lumen Rapid X at £34.99.
Maximum output: 100 lumens
Lezyne Strip Drive Pro rear light
Lezyne have revamped their range of lights and the Strip Drive Pro is among the new additions. Like the CatEye Rapid X3, it offers a maximum output of 100 lumens. Quite frankly, that's huge in rear light terms.
The illumination comes with five LEDs through a MOR (Maximum Optical Reflection) lens which offers a decent reasonable amount of side visibility. Those five LEDs combine to produce nine modes: blast, enduro, economy, five flashing modes, and an additional daytime flash, which is the only mode which takes full advantage of the light's 100-lumen capability.
In a smart move, Lezyne have designed the Strip Drive Pro to be both round and aero seatpost compatible. Once again, if you don't need a light quite as bright as this one, then the regular Strip Drive tones things down a little to 25 lumens for £26.99, but otherwise the two lights share a similar construction and range of modes, and the full-fat Strip Drive Pro version looks good value to us.
Maximum output: 100 lumens
Light & Motion Vis 180 Silver Moon
The Light & Motion Vis 180 Silver Moon is a unique design which combines conventional rear-facing red LEDs with amber side lights. It's a design which offers illumination through 180 degrees, hence the Vis 180 moniker.
The Vis 180 Silver Moon has four modes in all. There are high (70 lumens), medium (70 lumens) and low (25 lumens) modes, with the red LED pulsing, solid and pulsing respectively depending on which you choose, and the two amber LEDs pulsing throughout. There's also an additional mode which just uses the amber LEDs, designed for use when riding in a chaingang, so you don't blind anyone sitting on your wheel.
The mount is a little clumsy, with a pivoting bracket which straps to the seatpost using an adjustable silicone band, but it's perfectly useable, if not as slick as some of the other setups here. All in all, though, this is a seriously bright light with a clever take on side illumination, even if it'll cost you more than most.
Maximum output: 70 lumens
Website: Light & Motion
Knog Blinder Road R70 rear light
Knog's new Blinder Road R70 ticks the box as a suitably bright rear light, with a maximum output of 70 lumens and a range of five modes, but what really sets it apart is the range of mounting options.
Knog have recognised that more and more bikes have aero-profiled seatposts, which are particularly tricky for rear lights, and so the Blinder Road R70 is designed to be compatible with both aero posts and conventional round posts. They've added a small channel into the mount of the light, which fits against the trailing edge of aero posts, as well as a longer rubber mount to fit around the larger profile of round posts. It also comes with three interchangeable rubber bands to use on varying size seatposts.
Other than that, the Blinder Road R70's five modes use the four main LEDs in varying steady and flashing sequences, and the light also has an LED strip which runs around the outside of the unit to provide side illumination in four of the five modes.
Maximum output: 70 lumens