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Kranx  Strix 100 USB Rear Light
39g £15.99

The Kranx Strix 100 USB Rear Light is a compact six-mode design putting out a maximum of 100lumens and boasting run times between 5 and 18hours. However, while genuinely very bright, peripheral punch is good, rather than great. Minor shortcomings aside, in my view, it’s a good, wallet friendly bet for pared to the essential's best bikes, or a frugal companion to a main/bigger rear light.

Pros:  Bright and effective, good run times, inexpensive, user-friendly.

Cons: IPX3 weather proofing.

bicycle cycle bike rear red light



Reminiscent of Moon’s Ring Rear Light, it measures a decidedly bijous 44x30x14.9mm and is a monocoque design where the mount is built into the casing, keeping things neat, while ruling out bracket loss. A win-win in my book. The body is composite, and the lens made from polypropylene. It feels relatively solid and the port cover, an exact fit. 

However, it only meets IPX3 for weatherproofing. This means it’s designed to resist water spray/splashes. Tolerances are slightly lower than the more common IPX4, so I would be inclined to mount high on the bike and add a precautionary blast of silicone-based spray, or grease to the port plug.  

Behind the lens we have 16 COB diodes and below that, a battery life/charge level indicator. A 500mAh lithium-ion battery supplies the power, is reckoned good for 500 charge cycles- a good two year’s hard use, give or take and refuels from the ubiquitous micro-USB charger. The supplied cable is a reasonable length for mains, laptop and indeed dynamo charging.

Modes/Switch 3.5/5

There are six-three steady, three flashing. 25, 50 and 100 lumens, which is sensible for most contexts. Curiously, there’s no mention of a memory function but ours seemed to default to my last selection. A single ½ second press powers up/down and single presses will course through the steady modes, a double prod selects the flashing menu-from here, single prods move it from low, medium and high. It’s a big, centre mounted affair, so a cinch to spot and use, even in full finger, winter-weight gloves. Ours has holidayed in pockets and bike luggage without any unwanted engagements but I’ve tended to keep it in segregated sections, not bouncing around the bottom of a pannier. 

Mount 3.25/5

bike bicycl;e cycle velo rad light rear red bag

This is integrated within the light, meaning you can’t lose it and rotates, so you can select the right angle. By default, it’s a clothing/luggage clip and has proven reassuringly secure. 

light red rear bicycle cycle bike
bike cyclist bicycle light red rear jacket

This has hooks, so for post mounting, simply slip the rubber “ladder” strap around. This is equally reliable, at least on post diameters between 25.4 and 31.8. However, the wrong profile for seat stays and similarly thin tubing. Given my comments re weatherproofing, I’d be inclined not to mount it too low, in any case. Predictably, a rummage through the bodge box confirms other straps will fit, although replacements are also available. 

Output 3.75/5


Despite a small surface area, the Strix is very conspicuous in all settings. Given the outputs, I’ve been more inclined toward the steady modes through town (although the 25-lumen flashing does have an edge when entering the flow of traffic, tackling roundabouts etc). Positioning also plays a part. I’ve found ours most effective when attached to wedge packs and saddle bags, including the Axiom City Wave City+ Seat Bag .This keeps it at driver eye-level and ensures peripheral punch is similarly effective, even at the lower, steady modes.  Starting with the flashing modes, the full 100lumens seemed visible to 350 metres on the darkest roads, further at dusk/dawn. 

Though not marketed as such, it’s also proved surprisingly conspicuous as a daylight running mode-around 250 metres in cloudy to sunny conditions. The 50 lumen is also highly effective. Friendly acquaintances suggest they could spot it at 275 metres on a clear night, dipping to 220 when conditions turn misty. The 25 lumen is still surprisingly assertive-enough bite for semi-rural contexts and if you needed to conserve power along those unlit backroads. Visible to 175metres through semi-rural settings, 100-125 in the latter.

Less brash than some but still perfectly adequate, especially if you’re running it as a dynamo companion. I’ve also preferred it to the steady counterpart through town. This is particularly so when tackling roundabouts and otherwise entering the flow of traffic.  That said; the steady 25 lumen setting is arguably best for group rides and still visible to around the 80-metre mark.

The 50 lumen is the way forward if you wanted a steady setting and on rides taking in rural, suburban and town stretches. Good for 160 metres, dipping to 120 through built up areas. However, even allowing for the closely knit diodes, peripherally it's less effective than its flashing counterparts. 

rear red bike bicycle bike light

The 100-lumen steady is visible to 200metres along unlit roads and relatively clear nights, dipping to 150, should you tackle the town and its competing illuminations. Again, while bright, especially at close quarters, it's not retina-tickling like a 50, or 100lumen flashing would be in these contexts, so unlikely to incite abuse, should you enter a more congested area.

Run/Charge Times 4/5

Tested in temperatures between 10 and 25 degrees, I’ve returned within a few minutes of the cited run times. Not surprising these days, but reassuring, nonetheless. Zero to hero, ours has mains charged in 90 minutes- 10 minutes or so faster, at the mains. Either way, the charge light indicator will turn red when it’s fuelling and green when fully juiced. There’s no auto kickdown, but this wasn’t a surprise, given the price and indeed, there are a few pricier models that don’t have this “limp home” facility either. Talking of which, I was surprised to discover ours powering down mid ride (and without visual indicator of low battery before setting out). No matter, since I had the Ravemen TR30M  as backup and this was an isolated incident. 

Care/Durability 3/5

Despite some misgivings about IPX3 for weather proofing, ours hasn’t missed a beat through some heavy downpours and I’ve even pointed a hosepipe at it. That said, I’d be inclined to pop it off when giving the bike a deep, sudsy bucket wash. Other than not allowing the battery to deplete too often between charges, there’s no reason it shouldn’t enjoy a reliable life.  

Value 3.5/5

£15.99 is good going, whichever way you cut n’ dice things. However, there are a few that might be less powerful on paper, but better bets if you were wanting a standalone light and low on your dough. This is primarily down to profile. Prime 360 Super Bright rear Light “only” pumps out a maximum 50 lumens (5 to 40 in the flashing modes), but the COB diodes and large surface area means its surprisingly extrovert. Admittedly, it was £19.99 but now reduced to £15.99. Then of course, there’s Oxford Ultratorch R50 Slimline Rear Light . Again, it “only” packs a maximum of 50 lumens but the profile and concentration of diodes means it packs a decent punch- a couple of quid dearer at £17.99. 


I’ve grown very fond of the Kranx Strix 100. Its compact, bright and sips reserves. In my view, it’s best on pared to the essential's best bikes, where you want to enjoy late summer evenings (or indeed crisp winter days). Contexts where dusk can sneak in, and you want something bright enough to power home with. It also makes a great backing singer to a dynamo, or bigger main light. 

Verdict: 3.75/5 Likeable budget light with decent output and run times. Ideally suited to summer best bikes, or a dynamo companion.


Michael Stenning


Bob Elliot Co Ltd - Suppliers of high quality bicycle supplies to registered traders (




Ryton On Dunsmore

Coventry  CV8 3FH


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