The Bike List

Klarus XT11 Flashlight £75

Tested by John Milbank, tester for The Bike List

Most of my time in the saddle is spent avoiding errant drivers and dodging stray animals – while the tracks and trails of my neighbourhood offer a fenland-flat excitement in the dark, it's the city-centre that really challenges me. In the winter months decent illumination is all the more important, and with dark back streets comes the need for a good quality front cycle light.

There are some excellent lights available for bikes, offering light weight and high output, but they do tend to come at a cost… While £75 may seem steep for a flashlight, when you compare it to other high-end torches and front bike lights it's actually rather good. A key point for me is also that it's quick and simple to pop off the bike and slip in my pocket when I lock up in town, and being a flashlight, it's great around the house, on hikes and when camping.

This is the next model up from the excellent (and still available) XT10 that I reviewed for The Bike List a year ago… this is also primarily a tactical torch designed for military and police users, hence the fit-inducing strobe and instant high-power when switching on. Being built to withstand some serious use has its advantages for us riders too though – the anodised aluminium body is extremely tough, standing up to being dropped onto concrete and rock without a mark, while the O-rings used throughout make it waterproof to 2m.

The XT11 offers a few features over the XT10 that are clearly designed for more 'tactical' users, such as a removable stainless steel front bezel, and optional coloured filters. Of more interest to us is the uprated 600 ANSI lumen output, compared to the 470 lumen of the XT10. Besides being brighter, a new XM-L U2 LED gives a whiter light, while the redesigned reflector gives a smoother, larger central spot to the beam. I've also found the new LED offers better efficiency than the older model, giving longer runtimes in both full and medium power.

Being a tactical torch, the XT series is intended for short bursts of output – for that reason Klarus have designed the light to reduce its power by 70% after three minutes (in high mode only, and this resets every time it's turned on). This reduction to 420 lumens sounds like a significant drop, but in use it's hardly noticeable. It's better to consider this as a very good quality 420 lumen bike light, with the capability for even greater power when you use it as a normal torch. It turns out that my older XT10 also reduces its output after three minutes, but I'd never noticed, which gives you an idea of the real-life implications of a small drop in output.

The medium power mode is where the XT11 will spend most of its time, and at 150 lumens it's more than enough for city work and all but the most aggressive of night trails. Low mode is only 10 lumens, which isn't enough to light the road, but is fine for simply marking your position or checking a map.

All this power is nothing if the battery doesn't last very long, but Klarus claim a runtime of 2hrs 20mins in high mode, and 7hours 20mins in low mode. Being a sceptical sort (and a geek), I built a basic test rig to measure the light output against time. Before looking at the graph it's important to note that it is uncalibrated, but it's very clear that using a Cytac 2400mAh 18650 battery (that costs just £8.95 from TacLight), I achieved nearer three hours in full power and eight hours in medium power before a significant drop in output.

As the flashlight reduces its light after three minutes in high mode every time its operated, it's fair to think that the battery life may be reduced by turning it on and off frequently. However, you'll see from the graph that I reset it every ten minutes on one run, with only a moderate drop-off in runtime, which is a great result.

So, it's a perfect bike light at a relatively budget price? Well, it's nearly perfect... the mode switch is relatively small, and takes a little practice to get used to, especially with gloves on. Also, many front lights created for the cycle market feature a battery level indicator, which is undeniably useful on a regular runs. However, they also tend to cost a fair bit more money, and when they do have replaceable battery packs, they can be expensive. Klarus lights start to flash well before they shut down, so there's no chance of flying down a hill to be suddenly plunged into darkness. Also, as its batteries are easily changed and very cheap, there's nothing to stop you keeping a spare one or two in your pocket.

A pressure switch is also available for the XT, allowing full control of the light without letting go of the bars. A great option for more serious off-roaders, but I prefer being able to just pop my light off the £4.95 bar mount for safe keeping in town.

You can run the XT11 on disposable or rechargeable CR123s, but it's best to use an 18650 (which is like two CR123s joined together), as it offers the largest capacity. While two disposable batteries come free with the torch, a charger will only cost you £13.95, so the total cost with a charger, a single 18650 and bar mount would be £102.80, which is still extremely competitive against even the cheapest pro cycle lights. It's worth noting that the charger takes around eight hours to juice up a totally flat battery, but being Li-Ion cells, there's no problem with giving them the odd top-up whenever you need to.

If you want a rugged cycle light that doubles up as an incredibly bright flashlight, the XT11 is an excellent choice. If you don't feel the need for the full 600 lumens then you might want to consider the cheaper XT10. Alternatively, Klarus have also released the XT2C, which gives all the performance of the XT10 but in a more compact package. Click here to see the review.

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At a glance

Verdict A practical alternative to bike-specific lights, with run-time and performance to challenge kit that's twice the price.

Klarus says:

Optional extras:

  • Swivel Bike Light Mount: £4.95
  • Klarus ED10 Pressure switch: £19.95
  • Helmet Mount: £4.95
  • Cytac Dual Bay 18650 Charger £13.95
  • Cytac Rechargeable 18650 Battery: £8.95


  • Two year warranty
  • LED Type: Ultra bright CREE XM-L (U2) LED with max output of 600 ANSI lumens and a life span of up to 50,000 hrs
  • Battery: 2x CR123A (3v) / 1x 18650 (3.7v)
  • Function: There are 3 light modes and 1 flashing mode.
  • Switch: Dual Switch operation; a protruding forward clicky tail switch for momentary-on, on and off functions and a second tail switch for mode selection (this is also a dedicated strobe, which can be accessed from any mode when the torch is on and also when the torch is off).
  • Performance: The XM-L LED delivers a lot of bright light (600 ANSI lumens) and is an efficient performer due to the digitally regulated output, which maintains constant brightness.
  • Protection: Reverse polarity protection circuit protects against incorrect insertion of batteries. Springs at the head and tail of the flashlight protect the battery and maintain constant connection. Sealed with O-rings for excellent water resistance and improved service life. Waterproof to 2 metres and Dust Resistant to IPX-8.
  • Tactical: A stainless steel crenellated bezel at the front is removable and coloured filters can be screwed securely in its place. The dual-button system provides complete, one-handed control over light modes and instant access to strobe. The removable clip allows the torch to be clipped onto webbing, a tactical vest or Police stab vest.
  • Dimension: 148mm (Length), 34.9mm (Head), 24.3mm (Body)
  • Weight: 132g (without battery), 180g (with 18650)
  • Finish: Tough, sealed body with HA Type III anodising.
  • Reflector: Orange peel to provide a smooth, flawless beam and good throw.
  • Lens: Toughened, ultra clear glass


  • Turn Power On/ Off
Pressing the protruding forward clicky tail cap switch will turn power On/ Off. Half-press will provide Momentary-On.
  • Switch Modes
When light is on, press the Mode switch (secondary tail cap switch) to cycle through High-Med-Low modes. Strobe is accessed by holding down the Mode switch for more than 0.8 seconds. Strobe can also be accessed when the light is off, by pressing the Mode switch.