Monday, 4 November 2013

Rear lighting for aero seat posts: Moon Comet R

With the winter drawing in, I had no choice but to start looking at a more elegant fix to my rear light conundrum with my Kuota Kebel.

There's a bit of history here because, whilst I've been using lights on my commuting bike for a week or so already, lights for my daily workhorse have never been an issue. This is the epitome of simplicity - everything is a standard size, shape or fit so pretty much any make of light is a possibility. The situation has never been quite so bountiful with the Kuota Kebel and ,with its custom aero seat-post, a lot more consideration is required.

Last winter (when my Kebel was my only bike) I had to make do with a very questionable botch involving a Knog Blinder rear light and regular, generous applications of tape! This worked but was never 'right' and when the Knog failed due to water ingress (don't get me started) I decided that next winter would see a proper, neat and effective solution to the problem. More and more manufacturers are employing their own aero seat-post designs (Giant, Bianchi Orbea, Planet X) so this is likely to be a problem that many have and will come across.

When I first started looking into aero clamps for rear lights I saw all manner of bonkers ideas and DIY clamps but none were befitting an Italian, carbon beauty like my Kebel! I started looking again with renewed gusto this September and had a bit of an epiphany when my cycling neighbour mentioned saddle-rail clamps. Kudos has to go to Matt because I doubt I'd have come across it so easily if he hadn't have mentioned the saddle rail type mount that solves this very issue. Simple but perfect.

Enter the Moon Comet R rear light!
This is a USB rechargeable light that puts out about 35 lumens, can be mounted vertically or horizontally and lasts for a respectable amount of time. Being a weight obsessive you'll not be surprised to learn that I've weighed it and comes in at 36 grams on my digital scales. Its light because of its lithium-ion battery and plastic construction but doesn't feel cheap despite its reasonable price-tag (Mine was put on a birthday list so was free but you can buy it for as little as £28.
The light has a narrow profile so when mounted vertically, whilst not truly aero, sits just behind the seat-post in a way that is in-keeping with the aero look and feel of the bike.
Moon_Comet-6Moon_Comet-2-2 Moon_Comet-1-2
There are 6 modes (3 too many in my opinion) all accessible from one on/off switch: Overdrive, high, standard, flashing 100%, flashing 50% and strobe. Moon quote a 1 hour 45 burn time on overdrive and 5hrs 30 on 50% flash. The most useful modes to me are flash, overdrive and high so I left mine on indoors on overdrive after its first full charge and clocked 1hr 51 mins. This was at room temperature though so I expect it will be significantly less in cold conditions when the battery will be under pressure. There is a helpful battery indicator built in and charging takes around 2 hours.
In terms of performance, I really like the light for its brightness and type of light it throws out. Moon describe the light as a 30-chip LED (demonstrated in the photo) and this gives off a very distinctive red light that's hard to ignore!
Moon_Comet-9(Underexposed to show the LED cluster)
Overdrive is very bright and really only necessary if cycling in busy traffic or in fog, when in fact the flashing modes are more likely to be more visible to other road users anyway? I will most-likely use the high mode since its main use is going to be quiet country lanes where I want to be visible but not to blind others in my group.

You get the saddle-rail mount which is a cinch to fit but you also get the stretchy rubber mount to fit a round seat-post. Because the light is a featherweight I hope the brackets will stand the test of time but Moon do sell spares if the worst does happen.
Now, I do have some negative observations that I should mention and the first is the on/off switch. Turning on from the seating position is difficult and in gloves I imagine this will be a complete lottery! I'm not sure that Moon could do much about this without making the button stick out more and therefore compromising the design. This won't be a big deal for most people and was an issue I only noticed when I started my ride just before dark and subsequently struggled to turn on whilst maintaining a safe trajectory! The only other thing to note is the side visibility feature - In my opinion this is virtually useless and a bit of a disappointment by all accounts.

Overall it's a great little light, even if the looks are bit on the ‘square’ side. I appreciate the subtlety and prefer the narrow profile to a more radical design. If you want to sex it up a bit you can go for a white version!


  1. Great review.
    I have question about the on/off switch: is there any protection against accidental switching (by example: need to press 1 or 2 seconds to switch on or of) in order to avoid useless lightning of bag inside ?

  2. Thanks for your comment, I hope you found the review useful.

    The light takes a second or two to turn on when the power button is pressed which is enough to prevent an accidental switch-on but moreover, the On button is placed in such a position that I think you'd find it difficult to turn it on even if this delay weren't there.

    Since writing the review I've used the light a lot on my Tuesday night rides and it's pretty much the perfect rear light - in my humble view!

    1. I purchased this light while in Sydney, AUS a few weeks ago. It is the most awesome rear light! I like the really fast blinking mode. It will really get a driver's attention!!!

    2. I'm convinced that this is possibly the only rear light I'll need. The clamp for the saddle rails is also adjustable for angle (as different people set their saddle angle differently) and its these small details that sets Moon apart - for me at least.