Knog Boomer USB review

Knog Boomer USB bike light product shot

About 12 months ago I thought I’d found my perfect bike light for cycling in London. I was wrong. The Knog Boomer USB is the perfect bike light.

I can tell you exactly why in three words:

Bright, chargeable and convenient

The Knog Boomer stands out as one of the brightest small bike lights I’ve used to date. I’m not the only one who’s noticed. I frequently get comments along the lines of “wow, your bike light is so much brighter than mine”.

With that level of brightness you’d think the battery would be always running out. Indeed, with it being a rechargeable battery you often have to put up with a shorter running time. Not so with the Boomer. I’ve been using it for three months and in that space I can count the number of charges on three fingers.

The third aspect of the Boomer I love is the convenience. It can be fitted and removed in under 5 seconds.

Needless to say I think that me and the Knog Boomer USB have a bright future ahead (Don’t forgive the pun).

Knog Boomer shown on handlebars with light turned on

So is everything perfect?

Absolutely not. But before I move onto the negatives there are two more things I’d like to mention.

If you are an astute reader of the comments section on London Cyclist you’ll also know that with a couple of Knog lights people have complained of waterproofing issues. I’ve tested three different Knog lights to date and haven’t had an issue with any of them. The Knog Boomer USB is no exception. In the two big downpours I’ve tested it I’ve not had any issues. If any long term issues present themselves I’ll report back on them here.

The second thing I’d like to mention are the four different modes of the Boomer. There’s three different blinking modes and the constant beam setting. From what I’ve seen so far the light doesn’t tend to turn on while it is in your pocket.

Onto the negatives

The Knog Boomer USB sits very near your handlebars. On occasion your brake or gear cables can get in the way. That means you lose out on some of the light that should be shining on the road. The difference is minimal, but it is worth noting.

My second complaint is how difficult it is to remove the Boomer from its silicone casing when you need to charge it. My guess is that it is designed that way to avoid water getting in.

In my three months with the Knog Boomer USB those are my only two complaints.

Overall, I’m going to give the Knog Boomer USB two thumbs up (5/5). I think it is an excellent bike light for riding in the city and the convenience of being able to charge up from your laptop is invaluable. At least as someone who is rarely away from a computer.

Buy the Knog Boomer USB


  • Bright
  • Waterproof
  • Quick to install
  • USB rechargeable


  • Sits a little near to your handlebars so the brake cable catches some of the light
  • Hard to remove the case for charging

Showing that we gave the Knog Boomer USB five stars

Review in brief:

The Knog Boomer Rechargeable USB is one of the best bike lights we’ve tested here on London Cyclist Blog.
Knog Boomer USB
Date published: 12/19/2011
5 / 5 stars

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30 Responses to Knog Boomer USB review

  1. Nick Beagin 19/12/2011 at 10:41 am #

    Mmm nice – might have to treat myself to an early Christmas pressie!

    • Andreas 19/12/2011 at 11:00 am #

      I know right? I think my house mate is expecting one of these off me!

  2. Dan 19/12/2011 at 11:05 am #

    Wait until the switch breaks and you can no longer turn the unit on. Happened to me twice after light, careful use. They are great lights while they work, but there’s clearly a flaw in the design of the switch.

    • Andreas 19/12/2011 at 1:21 pm #

      Oh dear – how long did it take for this fault to come about?

      • Dan 19/12/2011 at 3:14 pm #

        After maybe 3 months’ use. Shame because the design is pretty smart otherwise.

        • Andreas 19/12/2011 at 3:25 pm #

          Thanks for the feedback Dan – I’ll keep my eye out for that issue – I’m into my forth month of use so far. Did you get them to send you a replacement light?

      • Ronald Stewart 26/04/2012 at 11:18 pm #

        I have a broken button after 3 weeks regular use – now the replacement is broken after 3 days.

        Such a shame, the features are otherwise amazing.

    • Tim Mackley 10/11/2012 at 8:54 am #

      I found the light which shines in your face very off putting especially on flash, it’s like a strobe light and I thought I was going to have a fit. On constant it effects your night vision. I’ve fixed this problem by painting the top part of the lens with black paint, now it’s a great little light.

  3. Andrea Casalotti 19/12/2011 at 11:10 am #


    It is a good in-depth review.

    I am disturbed by the “Buy Now” link, which directs one to Amazon.

    1. Why are you supporting an American cowboy rather than London independent shops?
    2. If you are making money from people clicking through and buying the light from the afore-mentioned cowboys, shouldn’t you disclose it?

    • Andreas 19/12/2011 at 1:17 pm #

      Hey Andrea –

      Thanks for the comment. I do get a commission on any sales (6%). The money helps me run London Cyclist – if it wasn’t for these commissions I could never put as many hours into the site so they’d be a lot less free content on here from everyone to read. There’s a full disclosure of this on the about page:

      If you take a look at the product on Amazon it is actually sold by a third party and I’m sure Amazon take a commission. I believe my readers are smart enough to decide if they want to buy it off Amazon or head into their local bike shop and pick up the light there. That remains their decision. I’m always happy to support local bike shops and I’ve written about many great bike shops on the blog before. Plus I’ve got the London Bike Shop app that lists all of London’s bike shops. I hope the app continues to help people discover London’s independent bike shops.


  4. Lauren 19/12/2011 at 11:29 am #

    Hi Andreas, do you think the light strap on the boomer is big enough to fit around the fork of a bike? I have a basket so need a light to sit below it


    • Andreas 19/12/2011 at 1:11 pm #

      Hmmmmm – I’m away from home at the moment so couldn’t tell you – let me check when I get home tonight and I’ll post another comment here.

      • Lauren 19/12/2011 at 1:54 pm #


        • Andreas 19/12/2011 at 10:02 pm #

          Hi Lauren – I tried this on two bikes. On my old Raleigh it fitted fine but on my newer Hybrid marin that has rather wide carbon forks the strap wouldn’t quite reach around. However, if I pushed it slightly further down the fork then it was fine. The answer will depend on the size of your forks.

  5. elliot 19/12/2011 at 11:47 am #

    thx for the review. curious why you start by saying it’s the perfect bike light, then list several negatives.

    my issue with knog bike lights is that they’re small and cute, but so easy to switch on by accident in my bag or pocket – i’ve got through *lots* of batteries that way. rechargeable is better, but doesn’t get round the issue that i’ve had to cycle home without lights on several occasions, because the battery’s dead when i get the light out. in fact, this one would surely be worse, because you can’t even carry spare batteries with you?

    i’ve recently ordered reelights, which i first spotted at velorution, and which are powered by a magnet in the spokes.

    • Andreas 19/12/2011 at 1:20 pm #

      No bike light will be 100% perfect – this is simply the best one I’ve come across for the purpose of cycling in an urban area.

      I’ve not had the issue you mention of the lights coming on in my bag but I can see how that would be a problem. I guess you could always carry a small spare bike light with you.

      Would you recommend the reelights to others?

  6. James 19/12/2011 at 3:13 pm #

    Pffft – I’ve had 3 boomers now – the switch has broken on all 3 meaning the only way to turn them off was to remove the batteries. Serious design flaw.

    • Andreas 19/12/2011 at 3:26 pm #

      Interesting, Dan commented above on the same issue. I’ll be keeping my eye on my Boomer to see if the same problem arises. Is this on the rechargeable version?

  7. Andrea Casalotti 19/12/2011 at 3:37 pm #

    Our experience with Knog lights is that there are batches of faulty switches. It generally affects the Boomer and the Beetle, not the Skink and the Frog. When a customer has a faulty one we instantly replace it.

  8. Mariana 19/12/2011 at 5:50 pm #

    I bought one of those a whole ago and thought it was great… Until it broke three weeks after. It would not turn off anymore and therefore the battery would go in no time.

    Would not buy it again!

  9. Danny 19/12/2011 at 9:11 pm #

    I’ve had two of these lights. They’re great while they work. Then after a few months both of them wouldn’t turn off. Exactly the same as other people are saying on the comments list. I won’t buy anything from Knog again unless I know they’ve massively improved the quality of the product. Effectively, £60 down the drain. Could have bought a proper light that still worked for that.

    • Andreas 19/12/2011 at 10:03 pm #

      Danny – I’d assume the shop would replace it if you took it to them?

      It’s been interesting reading everyone’s comments. Obviously you need to watch out that you’ve not been hit by a faulty batch of lights.

      Be interested to hear if there’s anyone who’s used this for a longer period without any problems?

    • Hin 03/01/2012 at 7:59 pm #

      The switch on my Boomer USB just failed after four months. Over the last three days it gradually become less and less responsive till it finally quit today. I’m tired of Knog’s continuous quality control issues, I’ll never buy another of their products again.

  10. Neil 21/12/2011 at 10:37 am #

    Hi Andreas,

    I’ve often thought USB charged lights was a good idea, so I’m keen to try them!

    How many do you use on your bike? I was thinking that 2x front and 1x or 2x at the rear.

    Do they do them as a rear light too?

    Are there any signs that the light needs charging? or do you normally charge say once a week etc?


  11. Gabe 23/12/2011 at 10:39 am #

    Its a great light! To remove it, squeeze the rubber from the bottom like a strong pinch. Then it’s quite easy but it took me a while. It just pops out of its housing that way…

    • Leah 14/01/2013 at 1:09 am #

      I’m trying to remove it now and it’s not working! Just keeps slipping. Pinching is a good idea, but I can’t get a good grip. This is so frustrating.

  12. Ashleigh 23/12/2011 at 10:58 am #

    I have a rear light and another front light. Only additional problem I would say is that the on/off switch is a little too sensitive meaning it often switches on in my pannier without me knowing. this means that the battery runs down without me knowing. However it’s a fault that other bike lights I’ve had have had so I guess it isn’t a deal breaker…

  13. Ashleigh 09/01/2012 at 10:02 am #

    I’m now also having issues with this – I’m finding it hasn’t been holding the charge well recently – after a trip to work and back (appx 15 mins each way), the battery is gone and it takes a whole day at work or overnight to charge!

    Additionally, the rubber has snapped so I’ve had to tie it to my panier front. Anyone know if you can buy the replacement rubber part?

  14. Tim Mackley 10/11/2012 at 9:00 am #

    I found the light which shines in your face very off putting especially on flash, it’s like a strobe light and I thought I was going to have a fit. On constant it effects your night vision. I’ve fixed this problem by painting the top part of the lens with black paint, now it’s a great little light.

  15. Bob Cross 16/01/2017 at 7:11 pm #

    These lights are very poor and are beset with problems.
    Mine worked well for a good while and the switch was never a problem.
    Then for some reason it will not hold a charge and is now useless.
    I would not buy another.

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