Moon Comet X-Pro rear light review

Does Moon’s Comet provide unparalleled rear visibility?

Our rating 
4.0 out of 5 star rating 4.0
GBP £31.00 RRP | USD $41.00 | AUD $58.00
rear light for mountain bike

Our review

With impressive brightness, a good viewing angle and additional mounting options included in the price, the Moon is a really solid all-rounder
Pros: Excellent visibility; Lots of mounting options
Cons: Hard to use on the move
Skip to view product specifications

The Moon Comet X-Pro offers excellent visibility and is offered with a host of mounting options for a reasonable price. It has seven modes, so finding one that’s suitable for your needs is likely. It’s maximum 40-lumen constant mode will drain the battery in one hour 30 minutes, but it can last up to a claimed 19 hours on a more frugal setting.


Moon Comet X-Pro details and specification

With a thin, long design, the Comet X-Pro has an IPX4 waterproof rating that will protect it from water splash-back, a CNC aluminium casing that’s claimed to act like a heat sink and a USB rechargeable 500mAh lithium polymer battery.

The seven modes — three constant and four flashing — are cycled using a single button and give the light a claimed battery life of up to 19 hours.

Included in the box is a seat rail mount, a seatpost or frame mount with two different length silicone straps, and a clip mount for bags or straps.

The Comet X-Pro has low-battery and charging indicators, as well as a mode memory function, which means it should return to the same mode it was turned off in when turned back on.

Moon Comet X-Pro performance

In use, the Comet X-Pro is  easy to mount and fit to a bike with the supplied seatpost/frame mount, while the large silicone strap means it’s possible to get good purchase on the strap to pull it tight around the tube you’re mounting it to.

The supplied seat rail mount is a great addition considering the unit’s price, especially if your riding a mountain bike with a dropper post — it gets the light unit further away from the rear wheel as your suspension compresses.

rear light for mountain bike
Having a number of mounting options is a real bonus.
Alex Evans

If you don’t have much space on your bike’s seatpost or seat tube then it solves the issue of having to find somewhere to mount it. The seat rail mount also has angle adjustment.

The light can be mounted either vertically or horizontally on any of its mounts, which means it’s possible to get it almost entirely out of the way of the bike’s back wheel. The seatpost clamp is very tight and shrugged off impacts and rough terrain without twisting or moving around.

Mode selection is relatively intuitive; a double push swaps between constant and flashing programmes while a single push cycles through each programme’s respective modes. That said, while the button has a positive click, it’s not particularly easy to use on the move.

There are no pulse modes and the flash modes do have quite long gaps between each flash — it would be good to have a strobing mode or pulse modes for maximum visibility without using the constant setting, as is common on many of today’s rear lights.

rear light for mountain bike
Side visibility is excellent.
Alex Evans

The light’s beam is especially intense from the rear on full-power and casts an impressive amount of light on the floor behind the bike, improving visibility.

Side-on visibility is good, too, and the light can be seen up to an angle of around 80 degrees from the rear. From that point onwards, up to and beyond 90 degrees there isn’t a huge amount of projected light.

There is still some side-on visibility but this is mostly down to the light’s brightness and power rather than any beam.

On full power, the light lasts 1 hour 30 minutes, which is bang on its claimed run time. With the power offered, this is an impressive amount of endurance and if you wanted to extend run times the other modes should help.

For example, you get a claimed 2 hours and 10 minutes on the next setting (25 lumens constant), extended to a claimed 5 hours and 30 minutes for 15 lumens.

rear light for mountain bike
The power button doubles up as a low battery indicator
Alex Evans

Moon Comet X-Pro bottom line

This is a great light with lots of additional mounting options included in the price. It offers impressively intensity directly behind the bike, with a good viewing angle to boot.


Operation on the move isn’t perfect, but then few rear lights offer that kind of functionality, and it could do with a pulse or quicker flashing mode. However, the option to easily mount it both vertically and horizontally is a real bonus.

Product Specifications


Price AUD $58.00GBP £31.00USD $41.00
Weight 46g – Total weight
Brand Moon


Features Clamp weight: 19g (seatpost)
Light weight: 27g
Run time (max power): 1 hour 30 minutes
Integrated battery Yes
Light type Rear
Output (lumens) 40
Remote switch no