Moon Cerberus rear light review – it's not perfect, but this classic model is still very good

Versatile rear light with excellent 270 degree visibility and decent run times, but room for improvement with the mounting system

Image shows Moon Cerberus rear light mounted on bike
(Image credit: Emma Silversides)
Cycling Weekly Verdict

If you are looking for a light to fit a variety of seat posts, the Cerberus might be worth considering. The versatile mounting system and 270º coverage sets it aside from many other lights, it’s no surprise it’s won design awards based on these aspects. It’s not perfect though; the hinged mounting wings could be better positioned to improve stability and the rubber pad could do with a permanent fixing to keep it attached to the light. These niggles aside, the light is certainly a slick unit that will get you seen day or night.

Reasons to buy
  • +

    Excellent side and rear visibility

  • +

    Versatile mount to fit any shape of post

  • +

    Appropriate number of modes

  • +

    VLS

Reasons to avoid
  • -

    Mount design could be improved to give a more secure attachment

  • -

    Rubber pad easily detaches (so easy to lose)

  • -

    Button not easy to locate

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Moon’s Cerberus rear light has been around for a few years now. The innovative design was recognised when it launched in 2018 by Taipei Cycle d&i awards and again in 2019 by iF Design (opens in new tab)

It certainly enhances visibility on the road, but is it still a worthwhile investment fours years on, with so much more competition from the best bike lights on the market?

Moon Cerberus rear light: construction

A built-in 500mAh Li-PO battery powers three LED COBs – two lateral units and a conventional rear-facing unit.

The compact unit measures just 18 x 27 x 64mm and tips the scales at 35g. The Cerberus is mounted by way of two hinged wings, a rubber pad and an o-ring. Three different sized O-rings are supplied: 20-26mm, 26-35mm, 35-52mm.

The rubber pad acts as a cover for the USB-C charging port and a short charging cable is supplied. The unit has an IPX7 rating. 

Moon Cerberus rear light in the box.

(Image credit: Emma Silversides)

Moon Cerberus rear light: mounting

The mounting system is possibly the most versatile I’ve come across. Two hinged wings ensure that the light fits any shape and size of seat post without compromise. The range of supplied o-rings allows you to mount on narrow frame tubing if space is tight. 

For me, the hinged wings could be longer, or placed further down the unit to offer a more stable mount; they sit at one end leaving the other a little less secure. So, while it might be versatile, it's not as secure as it could be and this is a real let-down, in my opinion. 

The shape of the light adds to its versatility. I’ve actually mounted it upside down on some bikes; depending on your seat post angle the beam may shine downwards rather than to the rear if mounted the 'right way up'. 

Since the Cerberus doesn't come with a clip it can’t be hooked onto a rucksack. I've had it on a pannier rack (with the hinged wings flat) and a helmet. Off the bike, it's clearly not guaranteed to 'fit all'.