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Moon Ring Rear Light



Competent compact blinkie with sensible output but there are better options for racking up the miles along pitch black roads

The Moon Ring Rear Light is another small but mighty blinkie ideally suited to minimalist builds or around-town rides, but rather like its front sibling, the Moon Ring Front Light, run times in the most potent settings limit its horizons to middle distance commuting and winter training.

It shares the same COB (Chips on board) technology as the front light, allowing 15 diodes and a 3.5 volt lithium polymer cell to share a tiny 44 x 31.2 x 16.5mm shell. On paper at least, this arrangement, coupled with a CNC machined aluminium casing, fosters efficient cooling, so the internals stand a sporting chance of lasting a decent length of time.

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With some notable exceptions, USB ports render equipment water-resistant rather than waterproof, and if you're running this with a cyclo-cross/adventure bike or a mudguard-shy build, I'd pop a slither of silicone grease on the port plug to prevent water and gloop finding its way inside.

As for mounting, the bracket offers rock steady tenure around most common sizes of seatpost, including aero, from 25.4 to 31.8mm diameters – just swap straps. Helmet mounting is another option. With a quick tweak of its Phillips head screwdriver, the light can be positioned inline or horizontal depending on seatpost height.

A 'belt loop' clip enables easy tethering to jersey/jacket pockets and luggage straps. Woven nylon loops are the best bets – the glossy types commonly found on welded waterproof wedge packs proved less secure. A small section of lumpy lane ejected ours on two separate occasions, albeit without any obvious damage.

The centre-mounted switch is intelligently placed and allows easy engagement/mid-ride mode shuffling when mounted on the seatpost, although for the most part I made my selection before setting off. As with the front light, it requires a definite two-second press before coming alive, so chances of accidental engagement are pretty slim.

Memory functions – where the light 'remembers' the last setting it was on – are useful and increasing popular, but manually chasing through the six settings is hardly a deal-breaker. Arguably we only need two modes and, personally, the most potent flash (100% flashing) was my default for night riding proper, 25% flashing for murky days. Run as my only source of rear lighting, friends reckoned they could spot me at between 400 and 600m along pitch-black country lanes.

Pre-dusk, 25% flashing seems good for 300m, ditto Overdrive, with High and Standard dipping to 230 and 180m respectively. When competing with other illuminations on the road, this dips, but not drastically.

Helmet mounting places the light squarely at driver eye-level, seemingly improving prowess by another 50m in town, 100 in the sticks, although you'd need something bike-mounted to comply with road traffic law.

>> Check out our guide to the best rear lights here

Moon reckons the lens projects a 270-degree beam but peripherally; I have several designs boasting 180-degree sweeps delivering much better presence – especially when entering the flow of traffic from side roads or roundabouts.

Ultimately, the Moon's output and economy are in step with similarly sized super-blinkies and if you're in the market for a contingency light for best or time trial bikes, it offers low weight and commendable presence. I wouldn't want to rely on it as my sole rear light on long semi-rural/rural commutes and training rides, though.


Competent compact blinkie with sensible output but there are better options for racking up the miles along pitch black roads

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Make and model: Moon Ring Rear Light

Size tested: n/a

Tell us what the product 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?

Moon doesn't provide a description of this little light. I'd call it a very bright but not too powerful option ideally suited to bikes where clutter must be kept to a miniumum, but there are better options for dusk-til-dawn riding.

Tell us some more about the technical aspects of the product?

*1 pce 15 chip circualr ring COB high brightness LED

*CNC aluminium heat sink casing

*Rechargeable lithium polymer battery 3.7v / 280 mAh

*USB rechargeable

*Quick release patented univesal bracket fits all round and aero bars

*2 x Orings 20-35mm & 35-52mm

*Low battery, cahrging & fully charged indicator

*Automatic fully charged cut off system

*Side visibility


*Belt clip bracket

*270 degrees total light angle


*44mm x 31.2mm x 16.5mm


*Overdrive 25 lumens - 1 hour 30 mins

*High 12 lumens - 2 hours 45 mins

*Standard 6 lumens - 5 hours 35 mins

*100% flashing 25 lumens - 2 hours 50 mins

*20% flashing 6 lumens - 12 hours

*SOS 12 lumens - 7 hours 30 mins

Rate the product for quality of construction:
Rate the product for performance:

Good range of power options and quite potent but with some obvious trade-off in terms of run times. Despite small dimensions, it's very easy to use and swap between bikes. Good fit on standard and aero seatposts.

Rate the product for durability:

Reasonably well made and sealed from the elements in the showerproof sense.

Rate the product for weight, if applicable:
Rate the product for comfort, if applicable:
Rate the product for value:

Tell us how the product performed overall when used for its designed purpose

Overall, the Moon Ring is a very powerful little safety rear light with a sensible range of modes for most conditions. That said, moderate run times in the higher settings and small surface area mean it wouldn't be my only source of illumination when racking up the miles along unlit roads.

Tell us what you particularly liked about the product

Bright, user friendly and perfect for pared-to-the-essentials builds or urban/suburban riding.

Tell us what you particularly disliked about the product

Nothing, given the design brief, although similarly priced competitors appear better sealed against the elements.

Did you enjoy using the product? Yes

Would you consider buying the product? Quite possibly.

Would you recommend the product to a friend? Worth closer scrutiny if they wanted a small but compact model for commuting/training or contingencies.

Use this box to explain your score

Bijoux though powerful safety light, but run times and weather seals are average alongside similarly priced competition.

Overall rating: 7/10

About the tester

Age: 41  Height: 1m 81cm  Weight: 70kg

I usually ride: Rough Stuff Tourer based around 4130 Univega mountain bike frameset  My best bike is: 1955 Holdsworth Road Path and several others including cross & traditional road

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Experienced

I regularly do the following types of riding: cyclo-cross, commuting, touring, fixed/singlespeed, mountain biking

Shaun Audane is a freelance writer/product tester with over twenty-eight years riding experience, the last twelve (120,000 miles) spent putting bikes and kit through their paces for a variety of publications. Previous generations of his family worked at manufacturing's sharp end, thus Shaun can weld, has a sound understanding of frame building practice and a preference for steel or titanium framesets.
Citing Richard Ballantine and an Au pair as his earliest cycling influences, he is presently writing a cycling book with particular focus upon women, families and disabled audiences (Having been a registered care manager and coached children at Herne Hill Velodrome in earlier careers)

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