The Moon MkII Rechargeable COB Rear Light does its job well as a compact and bright unit. It's easy to fit to the seatpost or seatstay, making it a bit more successful than the equivalent front light, which I tested late last year.
Like its front light sibling, the MkII rear appears to be aimed at commuters looking for a small, easily removed light with USB charging. Whereas the front light suffered a bit from its shape, making it difficult to find a suitable mounting point, the long thin design works well on the rear.
The light comes with two rubber brackets that press into the back and allow it to be fastened securely to various diameters, from wide seatposts to narrow seatstays. The mounting system can also cope with aero seatposts using the different sized O-rings supplied. Those rubber brackets can come loose when the light is off the bike, making it possible to lose them if you're a bit careless – though spares are available.
There are eight lighting modes, half of them flashing, including a 'strobe' mode that gives out 10 lumens for over 10 hours on one charge. On the higher settings the light is very bright and attracts positive comments from fellow commuters. Side visibility is pretty good too, and the on/off switch is easy to use, even in gloves.
There is a warning light to let you know when the charge is getting low, but this is not particularly obvious, especially when the light is on brighter settings. This is potentially a problem because the light cuts out suddenly when the battery is flat. That said, it's easily avoided by regularly topping up the power via the supplied USB cable – a full charge only taking a few hours.
A compact and very bright light, but make sure you keep the battery level topped up
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road.cc test report
Make and model: Moon MkII 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 says: "The MK II rear light provides 50 lumens of light output, from a small light and easy to fit unit."
Tell us some more about the technical aspects of the product?
1 pce 30 chip COB high brightness LED
Rechargeable lithium polymer battery 3.7v / 500 mAh
3 x O rings 20-26mm / 26-40mm / 40-52mm
Rubber insert pads allow aero post, ISP propel and standard post fitting
Low battery, charging & fully charged indicator
Automatic fully charged cut off
300 degrees total light angle
39 degrees spot angle
93mm x 22mm x 17mm
Overdrive 50 lumens - 1 hour
High 25 lumens - 2 hours 15 mins
Standard 12 lumens - 4 hours 30 mins
Low 6 lumens - 9 hours
100% flashing 50 lumens - 2 hours 10 mins
50% flashing - 25 lumens - 4 hours 25 mins
10% flashing 5 lumens - 20 hours 40 mins
Strobe 10 lumens - 10 hours 40 mins
Well made, although the loose rear bracket can drop off when not fixed to the bike.
Easy to fit and use. The sudden loss of output when the battery is low could cause problems.
No problems so far.
Not cheap, but brighter than most compact commuter lights.
Tell us how the product performed overall when used for its designed purpose
Easy to fit, and very bright.
Tell us what you particularly liked about the product
The brightness of the light. Quick recharging. Easy to fit.
Tell us what you particularly disliked about the product
The sudden loss of output when charge low. Warning light not very obvious.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
About the tester
I usually ride: Genesis Day One Singlespeed My best bike is: Souped-up Cannondale CAADX
I've been riding for: 10-20 years I ride: A few times a week I would class myself as: Experienced
I regularly do the following types of riding: cyclo-cross, commuting, club rides, fixed/singlespeed, mountain biking
Andy Ward works his socks off for the NHS as a GP and teaching at Leicester Medical School. After a brief foray into road racing he decided it hurt less to fall off on mud and is now most likely to be found on his cyclocross bike. He recently surprised himself by completing the Three Peaks without breaking his bike or any limbs