The Bike List

Exposure Sirius Mk1 Front Bike Light £115

Tested by Neil Watterson, tester for The Bike List

I like nicely-crafted objects. And the Exposure Sirius light with its machined-aluminium finish has a functional, but pleasing, design, with neat heat-transferring ribs in the LED end. It's a powerful little beast too.

Top of the company's Ride to Work range, the Sirius has a single 360 Lumen LED, is powered by a built-in battery and charged via a USB lead. It has a single button for operating it and can power other items thanks to its inclusion of Smart Port technology.

Burn time is around two hours on full power, four on medium, six on low and it has a flashing mode. It clips to your handlebar with a rubber-strapped mount and it has a two year warranty.

Turning the light on isn't the most intuitive thing in the world. With just one switch, how hard could it be? Well, I had to check the instructions to find out. Rather than a single push to get the light to come on, it needs to be a double-click. Then you're straight into the high-power setting. If you want to save battery, simply click once to take it to medium then again to go to low.

Click it again and you get, er, high-power again. So, how do you get flashing? Simple, hold the button until it flashes once, then release. And switching it off? That has to be done from one of the steady settings: if you're in flashing, click the switch once to get it back to steady, then hold the switch down until it flashes twice to indicate it's switched off.

Confused? I was. I'm sure it makes sense, but after a month of using it I'm still finding it's not switching off when I thought it should or going to medium setting rather than flashing. I'm fairly sure it's user error on my behalf, but I can't help feeling that it's over-complicated.

On full-power the light is easily powerful enough for on-road commuting on urban streets. In fact, you can knock it back to the medium setting for that, but I've found I leant towards using the flashing mode for my commutes.

Unlike many of the cheaper lights on the market, the flashing mode on the Sirius has the constantly lit at low power, then pulsing brightly approximately twice a second. That means you're always visible to other road users, not playing 'now you see me, now you don't'.

On the cycle paths and tracks I use on my commute, I have tended to favour running the light on full-power. And in that setting it's easy to pick out obstacles on the track ahead - and it's the one 'commuter' LED light I've used that has been bright enough to pick out animals at a distance. Where I've never seen anything other than rabbits with normal commuting lights I've picked out foxes and even muntjac deer - animals which normally shy away before I get anywhere near them.

Using a USB lead to charge the light is a bit of a mixed blessing. It means you can easily top up the battery at home or work, but if you leave the lead at work and decide to head off for an evening ride, the battery may not have enough juice to get you to work in the morning. Admittedly, you could always carry the lead with you, but that sort of defeats the object of having a wireless light.

Mind you, the light does include some smart technology. It has a traffic light-type battery gauge built into the switch. Green means it's in good health, amber is medium, while flashing red means the battery is about to expire. And the light automatically dims as the battery drains, extending the burn time - it doesn't die all of a sudden. The switch LED flashes green when charging but, on my one at least, it doesn't seem to stop when full. Maybe I've never managed to charge it to full capacity, although I've comfortably exceeded the 'average full charge time' of 6 hours on several occasions.

The light also includes Smart Port Technology Plus, which enables you to power and recharge other items - handy, if that's the sort of thing you want, but a mere gimmick to me. And it involves more fiddling with the switch.

The light mount is fairly good, just a plastic clip secured to the handlebars with a thick rubber band. It holds the light at 90 degrees to the bar and this may annoy you, depending on your bars. The risers on my mountain bike curve almost instantly, so if I fit the mount to the left of the stem, the light points slightly left. And on the right, it points slightly right. The beam pattern has a good, medium range, so it still covers most of what you need to see, just sometimes you realise that you can see more one side than the other.

Talking of beam pattern, the light has a good spread of light, with a main focus diameter of about 46cm at 3 metres, dropping off slowly after that. The fact that it's not that easy to pin-point the edge of the main-focus circle shows how much peripheral light the Sirius puts out, and my un-scientific light measure test gives it a reflected measure of 1/25th second at f/8 at ISO 100 within that 46cm circle. That's considerably brighter than my benchmark Smart 35 Lux in the main focus area, and immensely brighter on the peripherals.

Although sold as a commuter light, I reckon you could get away with the Sirius for mid-speed night off-road riding. It only weighs 84 grams and you can centre it in the mount to balance it, so it won't bounce out of alignment. It doesn't quite have a wide enough spread for slow-speed technical off-road work, but for fast trails where you're looking ahead, rather than under your front wheel, it will do the job. Alternatively, buy an optional helmet mount (£19.95) and use it to supplement your bike-mounted off-roading lights.

Overall, it's a great little light. I'm sure I'll get to grips with the correct switching sequence over time, though I'd probably invest in a second charger lead, so I could keep one at home and the other at work.

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At a glance

Verdict Powerful commuter light with a very effective flash combined with steady light, making it easy for drivers to see you and where you are. Lightweight and robust enough for off-road use.

Exposure says:

New to the 2013 range is the Sirius.

The Sirius is aimed at the commuter and offers proven Exposure technology including Cable Free Design, Intelligent Thermal Management and Fuel Gauge Indicator at an affordable price point.

With an output of 360 lumens the Sirius gives more than enough light to navigate the darkest city streets, whilst the pulsing mode gives maximum visibility during daylight hours.

Supplied with the all new Sirius handlebar mount, it's designed to be quick and easy to attach and remove so it can be taken with you when you aren't with your bike.


Weight: 84g

Output: 360 lumens

Power: 2600mAh Lithium Ion battery

Burn time: 2h High, 4Medium, 6h Low

Emitter: 1 Cree XPG R5 LED.

Cable Free Design (CFD): A primary feature unique to Exposure Lights removes the hassle of cables and straps while utilising the range of brackets available.

Function button: 3 colour Mode and Fuel Gauge indicator.
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 (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.

Includes: Sirius Handlebar bracket and USB charger

Supplier: Exposure Lights, +44 (0)1798 344477,