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40g  £19.99

The Sigma Infinity Rear LED is a simple, yet surprisingly bright, single mode light that sips reserves and cuts it along the darkest roads without dazzling, or annoying others at close quarters. There have been times when I’ve missed a flashing option and though I’ve had no issues with the weatherproofing, IPX4 is best suited to well-dressed working/training bikes.

Pros: Simple, user-friendly, bright, frugal run-times.

Cons: Single mode may limit the appeal.

sigma cycle bike bicycle rear light LED seat post


Now, StVZO (German lighting standards) dictate that lights cannot flash; hence lights complying with this are steady only. The beam must also “cut off” at the top, which prevents approaching traffic being dazzled - the same basic principle as dipped car lights. The lens is made from polycarbonate and employs collimator technology, that came from laser guidance systems to project the beam most effectively and complying with the stringent German standards.

A single diode is fuelled by a 3.7v, 300mAh lithium polymer battery, reckoned good for 500 charge cycles - a good couple of years, even if you’re a mile munching, dusk till dawn kind of rider. Commuters could bargain on considerably longer, all things being equal. At 40g it won’t offend best, or even TT bikes on strict calorie-controlled diets yet feels reassuringly sturdy and while IPX4 is lower on the weatherproofing scale than some, the port-cover fits snugly, and I’ve had no issues. Oh, and it uses the ubiquitous Micro USB fitting, so no issues if you’ve forgotten/lost the OEM cable or need something a little longer.

Mount 3.75/5

The Infinity is designed to be post mounted, to project the light most effectively (although I’ve run ours halfway along the seat stays with no issues). The light body features integral lugs and a rubberised shim to achieve solid, slip-free tenure and attaches via a “ladder type” strap. I’ve had no issues with seat posts between 25.4 and 31.8 diameter and it's been equally reliable on slender seat stays. However, I’ve switched to a rubber O-ring type, for a cleaner aesthetic.

The instructions suggest pruning the excess strap but it’s very unobtrusive and best left, if you’re switching between bikes. Alternatively, it will also play nicely with the rubber, doughnut types too. However, complying with German standards, there’s no clothing clip. Designed for vertical mounting, you won’t need acres of post showing. I’ve had no problems fitting ours to my fixed gear winter trainer’s Cane Creek Thudbuster ST G4, or Ursula’s Kinket 2.1 Suspension Post , which typically sports a 20-year-old Carradice SQR Tour (fabulous, bombproof luggage but consumes a fair bit of post). 

Switch 4.5/5


This, which follows the less is more narrative. Clear denotes fully charged, green 71-10%, at which point, it turns red. A red switch and flashing green light denote charging and is easy to read. The switch’s rubbery texture feels surprisingly positive, so a single half second press powers up/down and there’s been no issues with accidental engagement, say when holidaying in a jersey pocket or bar bag. 

bike bicycle velo rad light rear red Sigma infinity test review
sigma german cycle bike bicyckle rad velo light rear review test

Charge/Run Times 4.25/5

Sigma cite 2.2 hours, zero to full and that bears out in the real world, too - tack on another 15minutes or so, if you are refuelling from a laptop/similar tech. Flashing red denotes charging, steady green-charged. It’s also reckoned to run for 16hours. Ours has consistently returned this, from a full charge and the charge life indicator also seems very accurate. 


Output 3.75/5

rad velo bike bicycle cycle light rear red sigma report test review

Sigma didn’t cite lumens and prefer to focus on visibility. I’ve run ours at dawn, dusk and on the darker nights, along unlit roads and have been pleasantly surprised by its punch. Used as my only rear light, friends reckoned they could spot me at 350metres on a clear night, 280 on those misty dawn outings.

red rear bike rad velo light

This seemed consistent, regardless of whether I’d mounted it to posts, or seat stays and dipped to around 200 metres though suburban and built-up areas, due in part to the competing, concentrated neon. Peripheral punch was better than I was expecting too, which is welcome everywhere but particularly when turning, or entering the flow of traffic.

sigma infinity rad velo bicycle cycle bike review test report light

Though generally conspicuous, I missed a flashing option and - testing aside, I had the Brightside Topside Helmet light running in alternating end mode, or double flash, as backup. Nonetheless, mounted high, it’s better at snaring the attention of bigger vehicles than most bike mounted lights. On the flip side, unless someone happens to be doing some serious wheel-sucking, there’s been no complaint from riders following behind for longer distances.

Durability 3.5/5

bike cycle bicycle rad velo light back rear red report test review

I’d be inclined to apply a precautionary lick of silicone grease to the port cover, if fitted to bike(s) shunning full-length guards during winter. Otherwise, ours passed my garden hose test and hasn’t missed a beat when it’s been raining dogs. The polycarbonate lens has taken the odd direct hit without trace and everything’s charging nicely, so no reason to suggest it won’t enjoy a long, dependable life.

Value 3.25/5

£19.99 is good, given the overall package. However, there’s quite a lot of choice. Topeak Taillux 25 USB is another simple, 3 function model that pumps out a maximum of 25lumens and a claimed 40hours run time (flashing). It also meets IPX6 for weather proofing. However, burn time in the steady mode can’t hold a candle to the Sigma Infinity, which is arguably a better option for longer haul group riding.

Oxford Ultratorch R50 Slimline LED Rear Light offers eight modes, is relatively frugal, potent, quick charging and unobtrusive. It’s also a couple of quid cheaper at £17.99 That said, I’d prefer a sturdier rubber strap. Little brother to the Ravemen TR30M, the Ravemen TR20 comes in at £19.99 pumps out a maximum of 20lumens and has 5 modes (two steady, three flashing). However, the Sigma Infinity’s run time is superior.


Ultimately, the Sigma Infinity has impressed me with its blend of build, price, output, and generous run times. The single steady mode and StVZO accreditation is likely to find fans with riders looking to follow the strict letter of legislation. Quick charging is also a definite plus, especially for commuting. In most respects, it delivers as a standalone light but on the very darkest roads and in some town contexts, I felt more conspicuous pairing it to a secondary, flashing light.

Verdict.3.75/5 Simple, bright light with great run times.


Michael Stenning




Ryton On Dunsmore

Coventry  CV8 3FH


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