Moon Ring rear light - review - Road Cycling UK

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Moon Ring rear light – review

Bright, compact rear light ideal as a safety or back-up light

The Moon Ring is a super compact rear light with a 25 lumen output which packs a punch despite it’s small size, but it doesn’t quite have the power or battery life to compete as a dedicated rear light for serious night riding or training.

Mounting the light to the bike is easy with two rubber O-rings provided, in 20-35mm and 35-52mm sizes, so you can strap the light to your helmet, fork, handlebars and other spots on your bike and person, as well as on the seatpost. Having the option of two O-rings also means the mount will work with aero tube profiles.

The light slots into the mount with a reassuring click, but I did have a slight issue keeping it at the perfect angle. You can adjust the beam angle by loosening a screw and moving the light to your ideal angle, but this is done in increments, so I couldn’t always find the perfect position. It’s a small niggle, though.

The Moon Ring is a compact rear light with a 25 lumen maximum output (Pic: Jim Clarkson/Factory Media)

The light offers a claimed 270 degree visibility, a feature useful in built-up areas when wanting to attract the attention of motorists approaching from anywhere but directly behind you. Pulling out of a junction, for instance.

The Ring has six settings, three static and three flashing. The standard modes offer outputs of six, 12 and 25 lumens, with run times of 5h 35m, 2h 45m and 1h 30m respectively, while the three flashing modes once again put out six, 12 and 25 lumens, but with run times of 12h, 2h 50m and 7h 30m respectively. Charging is via USB and there’s a small low battery indicator at the bottom of the light.

The 25-lumen static Overdrive setting is impressively bright for such a small light but the limited run time means you’re unlikely to get much use out of these setting on anything other than short training rides and commutes of 90 minutes or less, rather than longer night rides. That said, you do get more battery life out of the flashing modes, which makes the Ring a sensible option for riders wanting a small but bright back-up or ‘just in case’ light.

You can turn the light on or cycle through the six settings using the single, central button on the front, which is big enough to locate when wearing gloves, but I didn’t find any real need to change settings on the go.

– Six of the brightest rear bike lights –

The construction is solid, despite the tiny size – the actual light is only 45mm x 20mm x 20mm – with a CNC aluminium heat sink body and plastic mount. The LED uses the latest COB (Chip On Board) technology by organising 15 diodes in a ring to create a single bright, dense block of light.

The light comes with two O-rings to give a variety of mounting options (Pic: Jim Clarkson/Factory Media)

The unit is water resistant and testing included a ride of more than an hour in heavy rain, with the light sat in direct spray of the rear wheel, but the Ring stood up to the task. As a side note, the shape of the light and smooth texture of the unit also seemed to reduce or nearly eliminate anything like mud, road muck or grit climbing on to the light.


If you’re seeking a safety light for commuting, a functional back-up light or just a compact unit for a minimalist machine then the Moon Ring fits the bill. It doesn’t quite stand up to bigger or more powerful (and, by and large, more expensive) competition as a dedicated standalone rear light, lacking the outright brightness or battery life, but otherwise offers a selection of settings and an versatile range of mounting options.


– Very compact
– Bright for small size
– Mount is easy to use


– Can be tricky to place light at ideal angle
– A little under powered as a standalone night light


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