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43g £59.99

The Knog Cobber Mid Rear Light, is a quirky and clever model with four tune able modes, and outputs ranging between 170 and 15 lumens. Run times are similarly practical and there's a lot to like. That said, I'm not completely sold on the bracket, or the pimple type switch. By no means poor, both can prove a little fiddly and the bracket's composites feel slightly fragile, if I'm honest. 

Pros: Very Bright, eye catching, yet tune able, 2 year warranty.

Cons: Bracket feels a little delicate, switch a little fiddly. 

red rear cycle bicycle bike light

Materials/Specification 3.75/5

Behind the wraparound composite lens sit no less than 192, yes 192 tiny diodes. Now COB (Chips on Board) designs are, brighter. Mounting them directly on the circuit boards, means more can fill the same space, resulting in a more intense output. 

These occupy the entire surface, for a genuine and consistent 330 degree projection. There are eight modes in total, comprising of steady, pulsing, hybrids and flashing. In terms of output, were talking 15 to 170, in sensible increments and a memory function, means it will default to your last option. However, they are also user programmable, via the Knog app.

The Lithium polymer battery has the charge port integrated within the mount, meaning you can just plug it straight into your 5 volt, or mains charger port. Undeniably convenient but to me, felt like a potential weak spot, so I've tended to employ the adaptor cable. The light is reckoned fully waterproof, although no IPX rating is cited. 


Mount 2.5/5

The pack comes complete with standard and aero versions, and a choice of O ring/ "doughnut" straps. Using the "aero" post mount has allowed secure tenure to seatstays, trailer and other, less conventional hosts.

rear light trailer bicycle  cycle

Look closely and you'll note the light is secured via a magnet, rather than clicking into place.

bracket magnet light ike cyle fixing mount

Credit where due, the union feels reassuringly good but the composites a little delicate, so I'm not sure how well it will fare, in the longer term. Going back to the standard mount, this has entertained posts ranging from 25.4, right up to 31.8mm.  Pretty much what I'd expect and yes, I've even managed helmet mounting, with a bit of help from the bodge box.

Switch 2.5/5

This is a small, pimple type with a positive action. Size meant it occasionally proved tricky and "remote" wearing middle-weight full finger gloves, including Oxford Bright 4.0. On the plus side, the memory function (and ability to tune modes to taste, via their app)greatly reduces faff.  So far, its failed to trigger when holidaying in a pocket, or bag. 

Charging 2.5/5

Charging is very straightforward, whip it straight into your 5V charger, or via a cable, to the mains/ if the angle's a bit tricky. The direct plug in, has always felt slightly fragile, so cable has been my preferred option. 

Zero to hero mains charging took four hours, which isn't bad relative to the run times. I've managed to charge ours, using a dynamo USB system, with the dynamo off, in similar timescales. Fine on a tour perhaps, but something to consider, if refuelling from work, or meeting up with friends. In common with many other designs, a green light gives visual indication that its fully charged.

rear cycle red bicycle light gear accessory brake pivo

Weatherproofing 4/5

Knog cite the Cobber family as being 100% waterproof. This isn't backed by IPX accreditation. However, a 2year warrantee boosts confidence. Aside from some provocative tickling from my garden hose, during bike rinses, it’s been subjected to lashings of grotty water thrown up along waterlogged lanes and torrential rain. Never once missed a beat.

Output 5/5

Output is retina tingling good. In the steady flash and pulse settings, which belt out the full 170 lumens. Overkill for all but the darkest nights some might say (and I'd be inclined to agree). However, bang on for daylight running. Even on very clear, bright afternoons, friends said they could pick the beam patterns out from around 100 metres. 

The 100lumen side flash and 80 lumen "disco-flash" isn't far behind either, although as "day" modes these are more effective, when skies are slightly overcast. As a guide, friends reckoned closer to 50/60 metres, which is still credible, if you wanted to save a bit of juice, or along country roads with dusk creeping in. 

As we're always saying presence doesn't simply boil down to fire power. The curved lens delivers a much broader arc, which makes a world of difference at roundabouts, or when performing right turns.


Dusk and beyond, friends reckoned the claims of 800 metres were plausible in the very highest, 170 lumen modes, and along open roads.  The 100lumen side flash was reckoned good for 550 metres, rolling flash closer to 350-400, which is still very impressive.

Eco flash is 15 lumens and arguably all you'd need for town centric, or indeed group riding. On a few occasions where I've been a bit concerned about reserves, I've dropped to this and again, visibility along pitch black roads is anecdotally, around the 150 metre mark, nearer 85 through town, given the competing illuminations. 

I have occasionally switched to mid (35 lumens) when the Cobber was paired to a smaller, flashing model. Trailers and Tagalogs tend to get overlooked by a lot of drivers.

For these reasons, and on balance I'd go for the Large Cobber, if you wanted a trailer specific light. Especially a low-slung unit, such as my recently revamped Bob Yak homage. That said; the rolling and disco flash kept us firmly on most people's radars.  

Run Times 3.75/5

As I intimated earlier, these are very competitive, relative to the outputs and thus far, they're also very close to those cited. I've not come close to taxing the eco-flash's 100 hours yet (but that's a whole heap of commuting from a single charge!). 

However, I've returned 2 hrs 25 from the high (2hrs 30 cited) 2hrs 23 from the steady/pulse (2hrs 30 cited), 6hrs 22mins (170 lumen flash), rolling and disco flash, 4 hrs 24 (4hrs 30). There's a gentle nudge before reserves bottom out. No auto-kick down to eco-flash though. A missed opportunity, by my reckoning. 

Value 3.25/5

£59.99 is a fair bit for a rear light. Lezyne Zecto Drive Rear is a tenner or so cheaper and has a 250 lumen option, should you want the last word in daylight modes and the See Sense Icon Plus has some incredible, programmable tech, and also packs 250 lumens. However, it’s also closer to £80


Even allowing for the two -year warranty, I'm not completely sold on the bracket and the pimple type switch, is a little bijou in full finger gloves. Nonetheless, the Cobber's blend of power, tune-ability, effective stock modes and sensible run times are hard to fault.

Verdict: 3.75/5 Powerful, tuneable rear light with decent run times but mount feels delicate.

Michael Stenning




Ryton On Dunsmore

Coventry  CV8 3FH


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