The Exposure Sirius Mk2 is a cool little commuting option that's easy to fit and use, and bright enough to show the way even on unlit sections of road.
The Sirius is just 106mm long with a 28mm diameter (even less in the central section), and it weighs 90g. It really is titchy tiny. It sits in a simple plastic bracket that attaches securely enough to your handlebar via a stretchy rubber ring. The light comes from a single Cree XPG white LED driven by a rechargeable 2600 mAh lithium ion battery.
You turn the light on by pressing the single button on the back twice, then you cycle through the three different beams. The high beam has a runtime of about two hours, the medium beam four hours, and the low beam six hours.
I left it on high beam most of the time and that gives you enough light to see the way on unlit sections of road. I just did an hour's ride with it around the lanes and felt perfectly safe and confident, although if most of your riding is on unlit roads, you'd probably want something with a bit more power (such as Exposure's Strada that we've also tested).
The one negative I would point out here is that although the centre of the beam is intense, you don't get much peripheral vision so at times it felt a bit like riding down a tunnel. That might be important to you or it might not.
At dawn/dusk and on well-lit streets you can switch to a less powerful beam to preserve the battery. I'd say this light is best suited to rides where the majority of the time you're on lit roads, but with the bonus that it'll see you right on unlit sections too.
Oh, there's one other beam option too: pulsing. The idea is that you use this one in the daytime. Use it at night and it'll drive you nuts.
I did find that switching between beams out on the road could swivel the light forward on the bars which was a bit disconcerting... That's until I developed the 'hypodermic syringe' technique of gripping the clamp between my first two fingers and pressing the button with my thumb. That works pretty well. Even if you do push the light out of position, it's easy enough to drag it back in place while you're still on the move.
Unlike many lights out there, the Sirius's lens extends forwards from the light body to offer side visibility – you can be seen from the side as you pass through junctions, for example, rather than just from the front. It's a legal requirement to have a light with this type of illumination on your bike if you're riding on the road at night. The glow from this doesn't distract you because Exposure have thoughtfully added a 'glare guard' – a blacked out hood that stops it shining upwards. Well, you can see the glow a bit but it's a small price to pay for not being sideswiped.
The function button doubles up as a basic colour-coded battery level indicator, and when it's time to recharge you can do that via USB. The charge port comes with a silicone cover to stop any water or dirt getting inside as you ride.
I guess you could break the resin lens if you were really unfortunate/careless but you're never going to damage the machined aluminium body enough for it to make any difference. Plus, the British-made Sirius comes with a two-year warranty.
Neat commuter light with a beam that'll show the way even on unlit roads.
The light comparator
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road.cc test report
Make and model: Exposure Lights Sirius Mk2 - Front Light
Size tested: Black
Tell us what the light is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
It's a light designed especially for road use and, in particular, commuting.
Exposure say: Sirius is a light perfect for commuters. With a new lens giving exceptional side visibility while caring for the rider with a glare guard, the Sirius's 360 lumens is more than enough light to navigate the darkest streets and has a pulsing mode for maximum visibility during the day.
Exposure Lights have always been designed to get the maximum light from minimum sized unit and Cable Free Design ensures this is maintained. Utilising superb brackets Exposure Lights attach quickly, safely and securely for hassle free riding.
Intelligent Thermal Management is patented technology which constantly monitors the LED's temperature to ensure that they do not overheat and become inefficient. ITM keeps the LEDs operating at the optimum output, saving battery power and maximising burntime.
The function button doubles as the classic Exposure Lights fuel gauge, displaying the remaining battery life using a traffic light system to make it clear when it's time to recharge.
For the complete commuter kit the Sirius can be bought with the Flare rear light in the Sirius Flare pack.
Tell us some more about the technical aspects of the light?
Here are the tech details as given by Exposure:
Output: 360 lumens white light
Burn time: 2h High, 4h Medium, 6h Low
Emitter: 1 x Cree XPG white LED.
Cable Free Design (CFD): A primary feature unique to Exposure Lights removes the hassle of cables and straps.
Function button: 3 colour Mode and Fuel Gauge indicator.
Charger: USB charger
Intelligent Thermal Management (ITM): Patented technology that combats the loss in efficiency of LEDs at elevated temperatures, maintaining optimum output keeping you shining 'Brighter for Longer'.
Smart Port Technology Plus (SPT+): Patented technology that enables a wide range of accessories to be used; Additional rear lights, back-up power supplies, remote switches and even charging other USB devices direct from your light.
Collimated Lens Technology: Exposure Lights use these high-tech resin lenses which have been extensively researched. These lenses are specifically designed to maximise light collection from the LEDs and efficiently produce an optimum beam pattern for cycling ensuring no light is wasted.
Weatherproof Body: CNC machined aerospace grade aluminium body with efficient heat transfer design. Fully manufactured in the UK.
Gold plated charge port: The charge port is gold plated for corrosion resistance, more efficient conductivity and it is sealed to a greater level adding protection to you light.
Storm Cap: The Smart Port in protected by a silicone cover to stop muddy gloves pushing dirt into the port.
It's a tough little unit, and it's weatherproof. Even if you do damage things like the charge port's storm cap or the bracket, you can get replacements very easily.
It could hardly be easier to use.
It's a simple bracket that's kept in place by a glorified O-ring. The one shortcoming is that you can move the light quite easily when switching between beams while on the move.
Tell us how the light performed overall when used for its designed purpose
Good output, simple to use.
Tell us what you particularly liked about the light
The build quality, tough design, decent runtimes, side visibility.
Tell us what you particularly disliked about the light
Quite easy to swivel the light forward accidentally while switching beam modes.
Did you enjoy using the light? Yes.
Would you consider buying the light? Would certainly consider it.
Would you recommend the light to a friend? Yes.
About the tester
Age: 43 Height: 190cm Weight: 75kg
I usually ride: My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding,
Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.