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Moon Gem 3.0 LED rear light



Nicely put together rear emergency back up light

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Moon’s Gem 3.0 is intended as a get you home safely back up rear light or the sort of thing you might take along to the summer race meet. Light, discrete and boasting cutting edge design, but most importantly of all delivering as a reliable and very convenient extra light attached to luggage and clothing. However, impressive as the seven to eight lumens are, the tiny pronounced LEDS don’t have the same presence as a bigger light, which can prove crucial negotiating junctions in unlit areas.

Common to the Moon range it sports an attractive brushed aluminium body, a clever adjustable strap with sufficient give to entertain most diameters of seat post/stay, although satisfactory grip on oversized 6061 aluminium carrier rod proved challenging. However, the 3.0 differs from its siblings in so much as the bracket detaches, revealing a handy clothing clip compatible with most tabs, jersey pockets and messenger bags.

A transparent red reflector runs around the perimeter, revealing the Li-ion battery and intricate parts, although while adding some token safety it doesn’t appear to radiate light. Four tiny LEDs sit proud of the brushed alloy panel and titter enthusiastically at the command of a dinky switch. Pleasing to the eye, it’s a bit hit and miss even with dexterous digits and positively frustrating wearing full-finger gloves. That said there’s nothing remotely toy-town about the build quality and despite my initial doubts the design seems highly water resistant in everyday use (although I’ve been very diligent in ensuring the dust cap’s firmly in place following USB fuel ups).

Charge times have proved pretty accurate ranging from three hours fifty minutes and seven hours thirty in high and flashing modes respectively. Powering up, the little diodes are surprisingly bright (you certainly wouldn’t gaze straight into their glare) proving most useful in strobe and flash settings, although they had a tendency to become lost in the clutter of neon shop fascias and other light pollution on busy high streets. Friends suggest we registered on their radar from around two hundred metres on a dry, clear night and the 180degree projection is adequate as opposed to astounding.


Meets the design brief but best as a back-up light test report

Make and model: Moon Gem 3.0 LED 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?

"With night riding &

racing more popular

than ever, it’s important

to have a set of small,

compact and

lightweight lights that

offer high performance

output for year round


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

3 Ultra bright red LED’s

7-8 Lumen output

24-26 LUX at 1m (180 degrees)

4 modes:

High Beam

Low Beam



Charge & battery indicator

Auto charge cut off

Optical lens

Side visibility

USB direct recharge

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

Moon's Gem 3.0 works very well as a chic, minimalist get-you home light or as a complement to existing lighting when attached to jackets, jerseys or luggage. The light is very bright but not particularly powerful and inclined to become lost in the excitement of the town centre. Similarly,other traffic drew very close along country lanes before acknowledging our presence. The Gem 3.0 will certainly get you home in emergency but wouldn't be my mainstay.

Tell us what you particularly liked about the product

Good output, easy charging.

Tell us what you particularly disliked about the product

LEDs could've been bigger.

Did you enjoy using the product? Yes

Would you consider buying the product? Possibly

Would you recommend the product to a friend? Generally, yes

Overall rating: 7/10

About the tester

Age: 36  Height: 1m 81  Weight: 70 kilos

I usually ride: Rough Stuff Tourer Based around 4130 Univega mtb 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, mtb,

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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