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Knog Boomer Rechargeable Front Light



Powerful blinky with funky styling like most of these type of light it is pricy… but it will save you a lot of batteries

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Good scores are more common than bad, because fortunately good products are more common than bad.

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  • Good
  • Quite good
  • Average
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  • Bad
  • Appalling

Knog's Boomer Rechargeable front light has all the brands' trademark chic and belts out a decent amount of light into the bargain. Arguably the most waterproof of the plug in breed thanks to those beefy neoprene covers, there's a genuine child-like wow factor seeing the battery and circuitry through their clear bodies... well there is for me anyway.

However, prowess and personality aside these are secondary lights and, that price tag does look steep. However it is worth bearing in mind the savings on batteries you will make and that the price isn't out of line with the other banchmark rechargeable blinky, the Electron Backupz USB Rechargeable also has an RRP of £34.99, mind you the USB rechargeable version of the Blackburn Flea is almost a tenner less while admittedly less powerful and non-rechargeable, shop branded homages give change from a tenner.

Weight conscious eco-types will be delighted by the triple whammy of a ten- gram weight saving over the non-rechargeable Boomer and of course a three hundred charge cycle, so you'll recoup some cash while reducing the environmental impact. Worse case scenario, run perpetually at top whack they'll still return three hours per charge - 900-odd hours so around three years commuting before journeying to the great bike shop in the sky. That equates to around 25 changes of battery in a non-rechargeable Boomer - quite a saving on batteries. Partnering the super-bright LEDs are collimator lenses for a really sharp, targeted beam. Typical zero to hero charges consume two and a half hours, the lens turning from red to green, denoting it's ready to go.

Despite Knog's assurances that internals remain unchanged, ours seemed comparatively brighter in all settings than the Boomer we tested last year-something we noticed on the standard Boomer we got in to the office at the same time. A soft, rubberised switch toggles effortlessly between the settings; of which steady was by far my favourite, cutting a swathe through dusk's gloomy curtain-perfect for savouring summers' last on the best bike before winter arrives with a vengeance. Bijous dimensions, neon din and congested traffic equate to around 250 yards effective visibility, although this improves considerably (400 plus) through the suburbs and calmer country lanes on a clear night. A deft prod to the flashing modes extends run times considerably and proved a particularly good marriage with dynamos-especially those with so-so peripheral presence.


Powerful blinky with funky styling but these types of rechargeable light are expensive but probably not as expensive as all the batteries you'd use over the life of a standard Boomer


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Make and model: Knog Boomer Rechargeable Front Light

Size tested: Blue

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?

"Recharge via USB. WATERPROOF!! superslim, flexible silicone body. Integrated lens and housing. Hold button down to 'turn off' in any mode. Low-battery indicator in lens. Smart battery saving storage mode". Funky safety light that's just good enough to see by.

Tell us some more about the technical aspects of the light?


BURN TIME up to 3.5hrs (steady), up to 12hrs (flashing)

DIMENSIONS 62 x 33 x 30 mm

WEIGHT 42 grams

BATTERY Rechargeable Lithium-Ion polymer

LED SPECS Super-bright HIGH powered white LED

LED LIGHT OUTPUT up to 55 Lumens

The battery discharge feature has been integrated into the electronics to optimize battery longevity. This feature should be activated when the light will not be used for an extended period. (i.e. more than a month) To activate mode simply hold down power button for 5 seconds after a full charge cycle. The LED will be active until the battery reaches the correct discharge level to which the LED will turn off and the unit will be safe for storage.

- If unit is stored for more than 3 months, repeat battery discharge

Rate the light for quality of construction:
Rate the light for design and ease of use. How simple was the light to use?
Rate the light for the design and usability of the clamping system/s

Universal fit on all handlebar diameters but catch can be a little tricky wearing full-finger gloves.

Rate the light for waterproofing. How did it stand up to the elements?

Passed my time honoured hosepipe test.

Rate the light for battery life. How long did it last? How long did it take to recharge?

Two and a half hours from zero to hero while run times seem near as damn it faithful to the three and twelve hours quoted.

Rate the light for performance:
Rate the light for durability:
Rate the light for weight, if applicable:
Rate the light for comfort, if applicable:

Switch is very easily engaged in winter weight gloves but hasn't seemed prone to accidental engagement in pockets or bags.

Rate the light for value:

Tell us how the light performed overall when used for its designed purpose

I was positively impressed by the Boomer's output which at top whack is just sufficient to navigate unlit rural lanes by. No less effective round town, peripheral illumination is better than expected-especially in flashing modes. However, these are tertiary/safety lights and not compliant with BS safety standards-something to consider if you are thinking of using them as primary lighting. It also has to be said that the same applies to many similar lights too.

Tell us what you particularly liked about the light

Pretty much everything given the design brief, although ouput and weather sealing seem a notch or two better than most of the USB fueled breed of blinky.

Tell us what you particularly disliked about the light


Did you enjoy using the light? Yes

Would you consider buying the light? On many levels yes but theprice-tag grates on me a little

Would you recommend the light to a friend? Quite possibly.

Anything further to say about the light in conclusion?

In performance terms it scores a seven I was very tempted to give it a six overall because of that price tag. The only thing that stopped me is the fact that the Boomer isn't out of line on price with similar lights... mind you, in my bood the are over-priced too

Overall rating: 7/10

About the tester

Age: 38  Height: 1m 81  Weight: 70 kilos

I usually ride: Rough Stuff Tourer Based around 4130 Univega mtb Frameset  My best bike is: 1955 Holdsworth Road Path and several others including cross & traditional road

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Experienced

I regularly do the following types of riding: cyclo cross, commuting, touring, fixed/singlespeed, mtb,


Shaun Audane is a freelance writer/product tester with over twenty-eight years riding experience, the last twelve (120,000 miles) spent putting bikes and kit through their paces for a variety of publications. Previous generations of his family worked at manufacturing's sharp end, thus Shaun can weld, has a sound understanding of frame building practice and a preference for steel or titanium framesets.
Citing Richard Ballantine and an Au pair as his earliest cycling influences, he is presently writing a cycling book with particular focus upon women, families and disabled audiences (Having been a registered care manager and coached children at Herne Hill Velodrome in earlier careers)

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