Rear light for aero seat post

I spent a lot of time trying to find a light that would fit around an aero seat post. The most popular option seems to be to put a light under the saddle. But, I didn’t want that because I often have a saddle bag there or possibly a rear bottle.

Exposure rear flare

One of the few which seemed to fit was this exposure rear flare. It is a fairly bright light with 75 lumen red beam. It can be seen from quite a distance. It is quite popular amongst time trialists because it is quite small and aero, but gives off a reasonable light that can be seen from quite a distance.


Exposure flare light.


It’s a bit of a stretch to get around this aero seat post. It also needed some blue tac to make the light stay in place. It can still sometimes move direction a little.


It is fairly easy to use. You just twist the glass into different positions. There is constant or flashing mode.

Some riders have reported that if you go over bumps, it can switch mode. If you contact Exposure they may send some contact pads to fit behind the springs. One tip for using is that make sure you tighten the cap tight as this seems to help keep the light in the right mode. Though be careful not to overtighten as the threads are susceptible in the long-term.

Once it is attached to the seat post, you can pull the light out of the holder.

Weight: just 36 grams

Batteries: small CR123 disposable or rechargeable

You can buy a saddle mounted attachment as well. Though this does not come with the light, and has to be bought separately.

It’s a good little light, which gives a high output of light for the size. It’s easy to put on and off, and fits around an aero stem which is a good thing. The main test will be how well it survives in long-term use.

Long term review

I have used this for the 2015 season, but I find it does tend to move around. It is OK, but it wouldn’t be my first choice for TT bike.

Knog Blinder R70 – adjustable straps


Finally, a rear light specifically designed for aero seat posts. Well not specifically, but there are different lengths of straps to go around the seat post. There is also a small indentation in the back so that it fits relatively snuggly around the aero seat post.

It is very bright and has good all round light – it is significantly better than the USE exposture.



6 Responses to Rear light for aero seat post

  1. paul heggie August 2, 2015 at 11:29 am #

    had one but threads stripped far too easily-now have a cateye rechargeable which fits nicely round aero seat post

  2. tejvan August 3, 2015 at 6:58 am #

    Cheers Paul, I wonder if it is longer than a Because I got that hoping it would go around aero seat post, but it didn’t

  3. Ray Claridge August 3, 2015 at 1:24 pm #

    I’ve been using one of these on my TT bike for a couple of years with no problems. I have cable tied mine to the saddle rail under a Adamo saddle, bright enough to be noticed even in daylight.

  4. Harry August 3, 2015 at 2:04 pm #

    I’ve got one of the cateye rapid’s that Paul links to and it has an elastic band fitting which stretches quite well round an aero seatpost. It didn’t sit very neatly against the post though and I moulded a new one using sugru (basically plasticine which sets hard,

    However, the light isn’t that visible in daylight so I’m not convinced it is useful for TTing. I ended up upgrading to one of these instead:

  5. Greg August 27, 2015 at 11:29 pm #

    I’ve now got a Moon LX-70 which comes with three rubber moulds for the back of the light, the most pointy of which is a good fit to the seatpost on my P3. ( I have no connection with Moon etc etc)

    • Fernando April 29, 2016 at 4:41 pm #

      How can we order products from moon in the U.S.?

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