Knog Blinder 4V Review

Knog Blinder 4V shown on rear of bike

It’s fate.

Just as my Knog Skink LED Rear Light decided it no longer wished to serve me, and packed up, leaving me riding home with my front light on the rear of the bike, Knog got in touch with me about the Knog Blinder 4V.

Would I like to test it out?

I certainly would, as I needed a new light!

The Knog Blinder 4V is one of Knog’s newest bike lights. It’s so new in fact, that as I sit here typing this post with the Olympics on in the background, you can’t even buy one.

Knog will be introducing these for around £30 at the end of August, in eight pretty colours.

When they finally arrive to the shop shelves will they be worth a purchase?

Let’s start off with the obvious good things. The Knog Blinder 4V is small, bright, it’s quick and easy to install without any tools and it’s USB chargeable. These are the things I love about most the Knog lights.

Knog blinder attachment mechanism

Let’s start with the attachment via the silicone strap. Unlike previous models I’ve tested, there’s a plastic clip that snaps shut. This works really well. However, there is a limit to how wide a seatpost this will attach to. If you’ve got an unusually shaped one, then you may wish to reconsider. According to Knog, it should fit 22mm to 32mm seatposts.

Once again, the Knog tool less installation design is great for anyone with more than one bike.

Knog Blinder 4V charging up

The Knog Blinder 4v is USB chargeable. A small USB attachment pops out from the unit and plugs in to your laptop. Except, there’s an issue here. When I tried to plug it in to my laptop, I couldn’t. Due to the design of the unit, I had to lean my laptop off the side of the desk to plug it in.

This is not ideal but obviously won’t be a problem for everyone. In the end, I attached the Knog Blinder to the plug that comes with the iPhone.

While the bike light is charging, you’ll see a red light. This changes to green once it is fully charged. The red light also appears when the battery level is low.

Knog blinder with the light on

The Knog Blinder 4V features four different lighting modes. Constant, flashing, strobing, top to bottom and outside light then inside flashing. The strobing mode is very attention grabbing so it’s a good one to use on your bike.

The light delivers a total of 44 Lumens. This is less than the 60 Lumens provided by the Knog Skink however, it’s still impressive and in practise it is still really bright.

The Knog Blinder promises 3 hours of light on the steady mode and up to 50 hours on the flashing modes.

To turn on the light you need to hold down the button for two seconds. This helps reduce the chances of the light turning on by mistake while it’s in your bag.


Overall, the Knog Blinder is really excellent. At £30 it has to be. Should you buy it? Possibly. I’d be tempted to also take a look at the Knog O Blinder. The square design delivers 80 Lumens of light – which is extremely bright.

The only thing that worries me about the Knog Blinder is that it will follow the same path as my Knog Skink. If it does, Knog do offer a 2 year guarantee so it would be easy to replace. Unfortunately, I can’t comment on the long term quality of the Blinder 4V but I’ll report back if there are issues.

Checkout the Knog website for more details on the Knog Blinder.

Update 1: Waterproofing

A number of people asked about waterproofing. I ran the light under the shower for two minutes and it is still working fine. Not a scientific test perhaps, but a good sign.

Knog waterproof light

Update 2: Flashing modes

Quick video above that shows the different light modes (and waterproofing).

Update 3: Bike light during the day

Question in the comments: Would this bike light be useful during the day? This isn’t something I’d personally use it for. I believe the Knog O Blinder may be more appealing, as it delivers more Lumens.

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34 Responses to Knog Blinder 4V Review

  1. Cycle Assist 08/08/2012 at 10:17 am #

    Looks neat, love the USB charging feature. How robust does the clip seem?

    • Andreas 08/08/2012 at 10:32 am #

      It is just a thin bit of plastic but I can’t imagine it would snap unless you mistreated it!

      • James 11/08/2015 at 2:14 pm #

        Well, I put mine on my seat post (normal width) bianchi via nirone 7, and came into the kitchen the next morning to find the rubber had snapped!!! £40 up the spout and it’s not even been out! Gutted. Will be taking it back to the shop and hoping they’ll replace it! Might have to tape the front one on just in case as I don’t feel confident 🙁

  2. Simon Norton 08/08/2012 at 10:45 am #

    Looks good. In my part of the world (The West Country) we have had rain (no really?) Is this product up to repeated soakings?

    • Andreas 08/08/2012 at 11:17 am #

      Yep the light shouldn’t have a problem. Again, I’ve not long term tested it yet so can’t comment if this changes over time but I’ve not heard anyone report issues with water getting in.

      • TDK 11/08/2012 at 2:32 am #

        I have the Knog rear standard blinder light, and commute to work every workday, in the sun, in the rain, and all sorts, and have never had the light soaked in water, so you will never have to worry about it being drenched.
        Why? Simply because it sits under the seat and your bike is going forward, the rain will most likely never touch the light at all.

  3. James 08/08/2012 at 12:07 pm #

    “The strobing mode is very attention grabbing so it’s a good one to use on your bike.”

    Has this ever been debated on LC? As a driver I detest flashing bike lights and mine are ALWAYS set to constant. I was annoyed when they changed the law on this.

    As a driver I rely a lot on rear lights of cars and bikes, flashing lights distract me, in fact, worse, they attract me and draw me towards the source. If you have me driving behind you then you are much safer, in my opinion, with the lights set to always-on.

    Caveat: my personal opinion and experience. I also cycle in London 100+ miles a week.

    • Andreas 09/08/2012 at 8:43 am #

      Hi James – admittedly we haven’t debated this. I can see how it could be an issue for a driver. If I’m behind a cyclist with a very bright flashing light it can be a little annoying. Be interested to hear other people’s opinions on this. Perhaps a post could be in order as the days get shorter.

    • Chris 09/08/2012 at 10:04 am #

      I’m actually of the opposite opinion – as a cyclist but daily car commuter, I find a flashing light in my mirrors when in traffic makes it easier to distinguish a cyclist in heavy traffic from all the other lights in my mirrors.

      I guess you can’t please everyone!

    • philcycle 10/08/2012 at 4:43 pm #

      I think flashing lights are attention grabbing and obviously attached to a cyclist (or possibly a runner) so you know what to expect when you get closer.
      I believe the downside is that it is difficult (if not impossible) to compute the distance to the source. Hence I always run a steady and a flashing light in combination.

      • David Cohen 10/08/2012 at 6:27 pm #

        Agree about difficulty computing distance – I think this has been reasonably well documented at various times, so I also run steady and flashing together sometimes.

    • Jill 13/08/2012 at 2:12 pm #

      I agree with James.

      I get migraines, and like many others who get them (plus epileptics), flashing lights can bring these on. I cycle in London, and when I get stuck at a junction behind someone with a bright flashing strobe light, I have to block my eyes with my hands to keep from getting a migraine. Not very safe for me. So, you know, thanks for that.

      I’m no expert in epilepsy (although I am in migraines), but it seems your flashing red lights have brought on fits in some people:

      If you must go with a flashing light, please opt for one with a very slow flash.

  4. gordon 08/08/2012 at 9:14 pm #

    I think you should look at a fibre flare Andreas, extremely good bright light.

    • Andreas 09/08/2012 at 8:41 am #

      Thanks Gordon for the reminder. I’ve had one for about 12 months but haven’t written the review. Will try and post it next week!

  5. Adrian 08/08/2012 at 10:51 pm #

    I’ve been using the Knog Blinder circle on the back and front of my bike for the past two months and am very impressed with both, although my oversized handlebars push the limit of what I would be comfortable strapping the light to. Also the rear is angled to face the traffic rather than the floor which is a huge plus.
    Both are more than bright enough for the dawn/dusk riders to be seen but I haven’t been out when it’s fully dark yet. Hopefully my quest for rechargeable/bright/last more than 3 months lights is coming to an end after going through a flea(stopped charging) , moon gem 3(not bright enough) and shield 60(clip snapped off) since this time last year.

    • Andreas 09/08/2012 at 8:45 am #

      Sounds like you’ve been doing some very thorough testing! Hope the Blinder lasts the test of time 😉

  6. Big Softy 09/08/2012 at 2:03 am #

    I recently went over to USB rechargeable lights, and considered Knog.
    The main thing that put me off buying Knog is the fact that it’s a 2 handed job to attach them.

    On a related subject: Why can’t light manufacturers use a single standard for output?
    Lumens, lux, watts, candlepower. Just pick one and make it easy so we can make an informed decision.

  7. Peter Smith 10/08/2012 at 10:04 am #

    Hey Andreas. Nice looking light.

    Can you do me a favour? Switch the light on and put it through a full washing machine cycle? On cold, obviously. 🙂

    That should emulate some of the heavier showers we’ve seen this summer.

    And CatEye, if you’re reading this … please bump your guarantee to 2 years so I don’t have to pay my £40 a year CatEye failtax.


    • Andreas 10/08/2012 at 1:55 pm #

      Hahaha would make a great story if it came out intact right? Maybe I should just run it under a shower and see what happens.. (runs off to do that)

      • Andreas 10/08/2012 at 2:04 pm #

        It has survived! See image in the post..

  8. David Cohen 10/08/2012 at 11:28 am #

    Andreas, I’d be very interested to know what the light is like in day light, as I’ve started to think that rear lights on during the day do help get you noticed more… and this can mean getting more space between you and other road users.


    • Andreas 10/08/2012 at 2:36 pm #

      Hi David – I’ve added a picture but it plays down the brightness. I’d still probably want to opt with a light with a few more lumens if I wanted to be seen during the day.

  9. philcycle 10/08/2012 at 4:52 pm #

    I see that the light lies parallel with the seatpost and is therefore pointing downwards. LEDs have a very narrow ‘cone of brightness’ and that angling will be sufficient to severely reduce the visibility to a driver.
    (Oh so simple to make the case wedged at an appropriate angle so that the ‘beam’ is near parallel to the ground on the majority of bikes. I have noted that most Knog lights ignore this simple requirement.)

  10. rossithebossi 11/08/2012 at 4:52 pm #

    One thing that i’m curious about Knog lights is that if they’re attached to the seatpost without an angle adjustment available, surely it’ll be pointing down. Is this a problem?

    I’ve noticed it on the earlier ones where the beam angle is quite narrow.

    I have a that enormous 10 LED Cat Eye jobby on the back of mine and it’s great. It had four side LEDs!

    • Adrian 11/08/2012 at 5:50 pm #

      On the blinder circle I have, it is wedge shaped so it isn’t pointing to the ground, not sure if this one is the same but they are pretty much the same.

  11. gordon 12/08/2012 at 3:05 pm #

    a 2 minute shower after what we have seen this summer is a bit lacking, test should have been at least an hour to prove whether it’ll stand up to British weather especially as rear lights get hammered with water flicking off of the back wheel.

  12. Phil 13/08/2012 at 11:00 am #

    Not with mudguards and mudflaps they don’t. Aesthetics be damned, I would rather keep my feet dry and my drivetrain clean.

  13. gordon 13/08/2012 at 8:07 pm #

    Phil that is if they fit your bike, as my bike is a road bike they don’t have mounts to fit them ( bit of water doesn’t bother me anyway ) I use a Carridice sqr tour bag which protects me from rain fine but as my light hangs off of the back of this it gets hammered in the rain.

  14. Phil 14/08/2012 at 2:47 pm #

    Fair point; comfort being my objective, both bikes have rack, light and mudguard mounts.

  15. Vincent 06/09/2012 at 4:38 pm #

    You may want to revise your opinions of the Knog O Blinder vs. this reviewed, rectangular one. The O blinder has precisely the same number of lumens (44) in the red, rear version. So, brightness-wise, these are indentical. For the front, white Blinder lights, all Knogs are 80 lumens. Unfortunately they do not make a front, rectangular blinder, so the only option is to go with a front, square one in white and a rear, rectangular one in red, if you so choose. 🙂

  16. Big Softy 11/09/2012 at 1:08 pm #

    Hi Andreas.
    Thanks for the heads up on the problem with the flimsy clip on your Moon Shield.
    I got around the problem before it happened by gluing a couple of small slivers of wooden coffee stirrer between the clip and the body, and now it appears to be as robust at my Cateyes.
    Providing you leave a couple of millimetres around the edge of the clip it works a treat.

  17. Dave Yates 05/11/2012 at 1:03 am #

    There are so many features to like about the Knog blinder. Light, powerful, USB chargeable, attachable without tools or putting a mount on bars or seatpost, It doesn’t accidentally get switched on in a pocket or bag, either.
    But there’s one fundamental flaw – the clip. I read several reviews which suggested it wouldn’t last long, and in my case it lasted two rides.
    The Knog Blinder retails for £30 in the UK, and I don’t know many people who wish to shell out £30 on a bike light – even ones as sexy as these – every couple of weeks.
    The design fault could be rectified if the clip and the rest of the light were separate parts, with the former slotting into the latter.
    Knog could sell the clipse separately, so, when one goes, it’s easy to replace.
    This would surely suit all parties. As it is, the Knog Blinder is a classic case of style over substance, and I’m off to see what else is on the market that lasts longer than a fortnight.

  18. wafer 25/09/2013 at 2:33 am #

    My 3 months old V4 has the silicon stripe broken! Without the stripe, the light is ueless.

    Overall design is good, but the material is not reliable!

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