Like this site? Help us to make it better.


Knog Frog Strobe Twinpack



A good choice to keep you legally-compliant when riding at night

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.

What the scores mean

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

  • Exceptional
  • Excellent
  • Very Good
  • Good
  • Quite good
  • Average
  • Not so good
  • Poor
  • Bad
  • Appalling

The Knog Frog Strobe Twinpack in black is a low-cost yet user-friendly solution to maintain legal compliance when riding a bicycle at night. In a pinch you can see by the front light too.

Knog is an Australian bike accessory brand with an eye for quirky yet user-friendly design, and the Frog lights are a good example of this. Low cost yet usable, they do the job they set out to, and do it well.

> Find your nearest dealer here

Using CR2032 button cells means the Frogs aren't going to set the road on fire, hence I class these as 'legal compliance' lights – too weak to use in unlit situations, and nowhere near bright enough to reliably grab a motorist's attention. I did find myself navigating a completely unlit path one evening, and the front light was perfectly adequate to walk by, or maybe cycle at jogging pace – but don't expect miracles.

Knog Light Frog Strobe Twin pack Black - front.jpg

The white front claims 8.5 lumens and 80hrs flashing or 50hrs steady, the red rear 2.5 lumens for a run-time of 70hrs flashing and 40hrs steady. This discrepancy in output is down to red LEDs being less efficient than white. Frog's user guide claims there's a low battery indicator that comes on after a number of hours, showing as a red LED in the lens, but in a test running the lights from full to flat I didn't see it come on.

> Need a powerful front light?

In terms of run-time, expect to get about 30 hours before the output begins to drop away appreciably – but let's face it, run-time is dependent on the quality of your button cell supply.

Knog Light Frog Strobe Twin pack Black - rear.jpg

Both the white front and red rear have three flashing modes: slow, interrupted and fast flash, plus constantly on. Modes are selected by cycling through with a single click of the button, with a final click turning the light off. Of more interest will be the ability to turn off while remembering the last mode, with a long press. Then a single press will turn on at the last-used mode.

> Read more reviews of light sets here 

The buttons are underneath the one-piece silicone rubber body, but are prone to inadvertent actuation – so if you're piling them into a rucksack you might want to have a small plastic container to pop them into.

All in all, you can do worse than the Knog Frogs as legal-compliance lights that won't annoy you by needing endless button presses to get to your chosen mode of operation, and they fit on/off the bike quickly too.


A good choice to keep you legally-compliant when riding at night

If you're thinking of buying this product using a cashback deal why not use the Top Cashback page and get some top cashback while helping to support your favourite independent cycling website test report

Make and model: Knog Frog Strobe Twinpack

Size tested: 80x35x42mm

Tell us what the light set 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?

Tiny, quick-to-remove low-profile lights to keep you legal and get you out of a pinch.

Knog says: "Houston - 1987: a lab frog escapes from its enclosure and knocks a vile of stinky chemical gunk onto an unsuspecting LED, giving it special powers. The light escaped to a nearby medium security retirement home, where it spawned an army of multi-coloured freaks, hidden from civilization... until now."

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

LIGHT OUTPUT : FRONT 8.5 lumens // REAR 2.5 lumens

DIMENSIONS : 80 x 35 x 42 mm

WEIGHT : 19g

RUN TIMES : FRONT 80 hrs (flashing), 50 hrs (steady) // REAR 70 hrs (flashing), 40 hrs (steady).

Rate the front light for quality of construction:
Rate the rear light for quality of construction:

The rubber is tactile and strong, and the hook at the rear is chunky. I can't imagine breaking these.

Rate the light set for design and ease of use. How simple were the lights to use?

Press the button to turn on or change modes. Press and hold to turn off. Simples.

Rate the front light for the design and usability of the clamping system
Rate the rear light for the design and usability of the clamping system

Stayed put. Fast.

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

Survived dunkings.

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

The run-time for new CR2032s was correct – 30hrs on full.

Rate the front light for performance:
Rate the rear light for performance:

These really are more legal-compliance lights than anything else, and they do that job to an above-average level.

Rate the front light for durability:
Rate the rear light for durability:

Can't see them failing anytime soon.

Rate the front light for weight:
Rate the rear light for weight:

They weigh basically nothing.

Rate the light set for value:

Tell us how the lights performed overall when used for their designed purpose

As legal compliance lights for less than a tenner per end, they do the job.

Tell us what you particularly liked about the lights

The simplicity of mounting. And the low battery indicator.

Tell us what you particularly disliked about the lights

Nothing, really.

Did you enjoy using the lights? Yes

Would you consider buying the lights? Yes

Would you recommend the lights to a friend? Yes

Use this box to explain your score

I call them above-average due to the memory mode, and the quick on-off rubber strap.

Overall rating: 6/10

About the tester

Age: 43  Height: 183cm  Weight: 72kg

I usually ride: Merida Ride 5000 Disc  My best bike is:

I've been riding for: Over 20 years  I ride: A few times a week  I would class myself as: Expert

I regularly do the following types of riding: cyclo-cross, club rides, general fitness riding, mountain biking, Dutch bike pootling

Latest Comments

  • bigblue 24 min 40 sec ago

    Yes, genuine mail-ordered stuff (I assume, because it was from reputable shops) seems to sometimes come unboxed, sometimes boxed. I guess this is...

  • janusz0 49 min 7 sec ago

    I was out in my car today and joined a queue that followed a tractor with a trailer of "big bales" for about 5 miles today.  I was too far back,...

  • NOtotheEU 50 min 6 sec ago

    Agreed it's a s**tshow.  Lets hope that at least all parties involved don't want WWIII.

  • pockstone 51 min 30 sec ago

    Collisions between fast moving trains and cars tend to be 'short-lived'. It's the grief and misery thereafter that last forever. This bloke has got...

  • Sniffer 51 min 57 sec ago

    London Fire Brigade on Twitter: "Fires caused by sunlight can happen all year round, so keep mirrors, glass & reflective objects out of direct...

  • NOtotheEU 1 hour 6 min ago

    I've considered something similar to this but spring loaded. Pull it down into place until you filter then pull a lever on the bars to get it to...

  • Rendel Harris 2 hours 38 min ago

    I can offer free disposal services...

  • Rendel Harris 2 hours 40 min ago

    Never seen anyone riding like that with aerobars, ever! Sounds madly uncomfortable. Mine are about 70 mm deep at the deepest flat part, no problem...

  • Themadchemist 4 hours 25 min ago

    I've had 2 KMC chains fail on my campag 10spd equipped bike,probably 5yrs ago.. Fortunately they both broke within a mile of home and I was able to...

  • Awavey 4 hours 48 min ago

    especially when they can often take 4 to 5 of their 7 days just to send you the link to upload the clip, but the stats they publish, although they...