Moon Ring Rear Light

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.

Verdict

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