Product Review: Knog Bull Frog tail light

Knog%20Bullfrog.jpg I’ve been using the Bull Frog tail light($28) by Knog for a couple months already. Like all of the Knog lighting products, the LED/battery case is encapsulated and affixed to a bike by means of a flexible silicon body. Most readers have seen the diminutive Frog lights, now available in a variety of body colours. I like them, but the Frog’s single LED and CR2032 batteries don’t make for long-lasting brilliance. What I wanted was a commuter tail light.

I present the Bull Frog.


With 3 AAA batteries powering 5 LEDs, the light provides ample if not superlative illumination. However, the Bull Frog’s ease and versatility in attachment are what really sell this light. Strap this light to seat stays, seat posts or wherever…without tools and within seconds. Plus the narrow cross-section keeps the Bull Frog out of the way.

Available in translucent or black silicon bodies.


I wish light manufactures, or any other battery-powered bike accessories, would add a switch that’d automatically turn the device off say after 8 hours of use. That way, when the Knog gets triggered in a suitcase by pressure from your shoes, it doesn’t run for an entire 18 hour flight flashing at your socks.

What is the runtime of the light on flashing mode?  price? how about an action shot or short video clip?

Planet Bike SuperFlash.  No other tail like even comes close.  I have the mounting clip on all my bikes.

Dinotte tail light. It will make the cagers want to avoid you at any cost.

The Dinotte tail light isn’t so much a tail-light as is is a beacon with which to land aircraft.  That thing is REDICULOUS.  A riding buddy of mine has that, and we make him ride in the back of the group at night because you can’t possibly see when that thing is on.  It’s pretty damn amazing.

This light is great but as someone says above, it’s badly designed and always gets switched on in your pocket. You can solve this by snipping a small cross-section of garden hose and super-gluing it around the recessed light switch - my light hasn’t switched itself on once since I did it.

I wish then light worked better; I tried to travel with it and it got turned on in the case and flashed all the way to Shanghai. I also broke the light off the little circuit board when I tried to replace the battery, after it flashed all the way to Shanghai.

why not just take the battery(ies) when travelling with it…....?


because he has a tendency of breaking the light when trying to replace the batteries.  But Byron’s talking about the Knog Frog….not the Knog “Bullfrog” that I reviewed in this entry and that I still use.  I’ve explained the difference to him many times, but I’m going to have to give him a Bullfrog for it to sink in.

My Knog Bullfrog is still working fine now.  Yes, a Planet Bike Superflash is brighter, but the Bullfrog is a breeze to move from one bike to another.  I plan on upgrading to Planet Bike Blaze 1W headlights…probably two plus 3 extra mounts to serve my stable of bikes.  But I’ll keep just that one Bullfrog for my taillight.  Too easy.

What would be really great is if someone made a set of bike lights that didn’t have batteries but plugged in to recharge them.  I have rechargeable batteries for mine, but just making the light itself capable of plugging in would be an upgrade.

My brand new knog bullfrog light with 5 led lights snapped the first attempt to attach to my bike. Not impressed!

I still use the same Bullfrog everyday.  Lights are one of those products for which there are bound to be some duds.  In the last batch of about 40 Planet Bike 1W Blaze lights I purchased for the bike shop, I had 3 units with defective switches.  But overall the typical product is great; I just figure I got a batch with some duds.  If a 1W Blaze works from the start, I never see them returned.

So I pulled them from stock and warrantied them from the distributors.  Most retailers and distributors expect a small number of duds, so you should have no problem returning the item to the place of purchase.  If they have the same item in stock, they’ll usually swap out. 

If that doesn’t work, you can often contact the manufacturer for a warranty replacement.  In fact, Cateye prefers this method.  I am unsure if you can seek a replacement directly from Knog, since they are an Australian company with US import agents rather than a US office (this is assuming you live in Canada or the US).

I wish Knog would update their products with more attention to industrial design—gummy silicon wrapping an LED attached to a coin-sized battery; awesome! Also fragile, will blink it’s way across the Pacific if bumped in the case, and also hard to replace the battery without breaking the light.

Byron is talking about the Frog. Note that the Frog and Bullfrog are entirely different products within the Knog range.  With the Frog, almost 50% of the value is in the CR2032 batteries included with the light itself.  Honestly, I don’t expect much from that product for $12, nor do I think the Frog is that great of a product.  I’m also pretty sure Knog expects the consumer to put a Frog on their bike and ride, not pack the bike up in a case for flying to China.

Now if this were a light SYSTEM that cost $300, I’d expect A LOT better reliability.  I don’t own a such a light system because shop experience has shown that light systems DON’T meet my expectations.  I don’t like it when I call a manufacturer’s phoneline and I know from experience that I avoid the 10 minute hold for “warranty department” by first choosing “sales” on the voice menu (and I’m not talking about Knog here).  If I had money to burn, I’d buy 2 systems and alternate every week or so, so that I had some redundancy if (when) one failed.  And I’d need to replace or upgrade at least every 2 years.

I should write a whole post about light systems and how I hate them, but in the meantime, buy a light you like, but get it out of your mind that you just purchased a new family heirloom.

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