Exposure Sirius Mk3 front light – review

Is the Exposure Sirius Mk3 the perfect commuter light? It certainly puts forward a strong case.

Why? It’s compact and easy to operate, bright enough at 400 Lumens for urban commuting and steady riding on unlit roads, with a range of settings and impressive battery life, plus the bracket is a breeze to use and the unit itself is robust with a number of well thought out features.

The Sirius is one of 17 lights in the Exposure range and is designed, in the Sussex-based firm’s words, to “excel in urban environments”. It certainly does that but the Sirius bridges the gap between a light to ‘be seen’ by and a light ‘to see’ with, despite it’s extremely compact size (108mm in length, with a diameter and weighing 84g).

The Sirius is a doddle to setup and operate. The unit slots into a plastic u-clamp with little fuss and the bracket itself is strapped to the handlebar by a stretchy silicone band. It means the Sirius is easy to move between bikes, should you need to do so, and it sits securely on the handlebar. The bracket can be an afterthought for some manufacturers but Exposure have got it almost spot on here. Almost because when you change the mode while riding, using the button at the rear of the unit, the light can shuffle forward a little in the bracket. It’s not a huge issue but means it’s easier to keep a finger or two on the light and use your thumb to operate the button to stop the light sliding forwards.

That button is used to turn the light on (two clicks), choose the mode, shuffle between settings and turn the light off (one long click). The Sirius has seven modes offering varying levels of power and, subsequently, battery life. For example, mode one is the most powerful and serves up two hours, four hours and ten hours of illumination on the high, medium and low settings respectively, while mode seven offers ten and 24 hours of light on the high and medium settings, as well as an additional ‘SOS’ setting.

The idea is that you can choose the mode best suited to your ride, thus getting the most suitable level of illumination and the best bang for your buck in terms of battery life. You can also select a ‘pulsing’ setting in any mode by lightly holding down the button and this is a great option for urban commuting as the LED pulses while staying lit throughout – attracting a motorist’s attention while also helping them gauge the distance between you and their vehicle.

The Sirius’ maximum output of 400 Lumens means that it’s also capable of guiding you on unlit roads. The beam pattern is fairly narrow, as you’d expect from a light of this size, but it’s bright enough to pick out potholes and other hazards when riding at a steady pace. If you regularly train on unlit roads at night then you’d likely be better off with a dedicated (and more powerful) unit like the Strada Mk5 we reviewed last winter but the Sirius is ideal for commuting (particularly if your ride takes in both lit and unlit roads) or if you occasionally venture off into the darkness.

The battery life for each setting is also helpfully printed on the underside of the unit and we found Exposure’s claims to be accurate. The button also serves as a fuel gauge to show how much battery life you have, meaning you can adjust the setting or make a bee-line to the charger if you’re running low on juice. Speaking of which, the Sirius is charged by USB – but rather than using a mini or micro USB port, the Sirius has a DC port (protected by a rubber dust cap), which means it’s unlikely to be compatible with the cables provided by many other USB rechargeable lights (and if you’re anything like us then you’ll have lots of them). That’s a minor gripe but means you’ll likely have to buy another cable if you want one at home and work.

As we’ve come to expect from Exposure, whose lights are made here in the UK, the unit is robust and well thought out, made from CNC-machine aluminium and likely to stand the test of time. It’s a clever design, with the lens protruding from the front of the unit to offer plenty of side illumination – another tick in the commuter box – while there’s also a ‘glare guard’ at the top of the lens to stop the LED catching your eye while riding, and that’s particularly useful when using the pulsing setting. Exposure have clearly thought about the small details.


A couple of minor niggles aside, (the tendency of the light to slide forward in the clamp when operating the button and the USB to DC cable) the Sirius is a superb light for serious commuters (the £99.95 retail value dictates that it’s for dedicated winter riders) who need a compact torch designed to offer plenty of illumination when negotiating busy urban roads, while remaining powerful enough for stretches of unlit road or occassional longer excursions under cover of darkness.

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