Knog Blinder Arc 640 front light – review

A good-looking, smartly designed light with admirable integration, but not without its flaws

The Blinder Arc 640 sits atop Knog’s range of lights and features a high 640 lumen output coupled with a fully waterproof casing, USB charge port and a great design aesthetic. On top of that, it performed admirably in a variety of situations, but it’s certainly not without its faults. 

The Arc has four modes: high, medium, low and flash. Those varying intensities all have corresponding demands on the battery with the high beam giving a claimed 100 minutes of battery life that I found to be nearer to 90 minutes in use. Still, it was more than enough for a commute of around an hour, but not one for a longer training rider if you want to harness the full power of the light.

Speaking of which, while 640 lumen max brightness is a strong output –  and if you’re using it on lit streets and side roads it’s more than adequate – it felt distinctly under powered on rural roads. For anything more than the odd unlit road or off-road trail it lacks the beam width and power to allow for higher speeds.

The light uses a Cree LED which is part of the reason for the consistent brightness throughout the battery life, and there’s little to no dimming as the battery comes closer to running out. Overall beam spread is okay for standard use – on lit roads and similar – but only adequate for other types of riding. Another issue is the lack of any side visibility, which is a shame because those would certainly add a degree of versatility and would help keep you seen by motorists who aren’t approaching from head on.

I found the standard silicone band and hook clip that make up the mount allowed the light to slip, even on oversized bars. Part of that may have been down to the rougher country lanes I was riding, but urban roads still offer various potholes and bumps, and having to re-position a light as it constantly rotates isn’t ideal.

I solved this by looping the band around the brake and gear cables as well to increase the effective circumference of the bars. It’s not a perfect solution, though, and you can only do it assuming that your cable routing actually allows you to do so. I’d definitely have preferred a closer fit for the mount or a static bracket. The bonus of the rubber mount is that it’s very quick and easy to remove the light.

The integrated USB attachment is a nice touch, but if you plug it directly into a computer or wall socket, it can feel like the weight of a light is putting a lot of pressure on a comparatively flimsy appendage

Charge time is average – Knog claim around five hours – and the USB compatibility means you don’t have to carry any kind of separate charger which is always appreciated. The flip out USB connector here feels a little lightweight and it does seem to cause a little strain if you leave the light hanging from a USB port. The light does come with an extension cable if you don’t want to plug in directly, but it could do with being longer to make it really effective.

Looking around at the £90 price point, there are other options that purport to offer a little more. Having said that, the Blinder is a lovely design and purposeful in shape and size, but the mount is positioned at the back and with most of the weigh at the front end the rotation issues I covered earlier aren’t surprising.

An integrated rubber mount is a smart way of doing things, but we found that it didn’t hold tightly enough, even on oversized bars


Build quality is good, and for urban commutes and smoother roads the Blinder Arc 640 is a solid, well-powered and bright option, but there are a few niggles with the shape of the light, the USB hinge and lack of side visibility that, if addressed, could really improve the overall package.


– Good looking
– USB charging
– Brightness and run time more than good enough for urban riding and commuting


– Rubber mount doesn’t provide the best hold
– Actual mechanics of USB charging aren’t great
– No side visibility


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