most night lights are designed to attach to the seatpost. but while carrying a bag on the rear rack that area get's blocked.

some manufacturers sell cheap, awful, lights that attach to the rack (topeak) but i figure some kind of adapter would be much more useful (mostly since everyone may have night lights before getting a rack... i do :)

but my searches for such a adapter failed. do you know any?

This is one example of night light i have http://www.dealextreme.com/p/rechargeable-7-mode-red-5-led-safety-bike-tail-light-with-7-mode-2-red-laser-beam-35mw-90117 (i regret. do not buy, laser is useless snake oil. but the leds are OK. EDIT: regret #2, i had rain for the 1st time --socal-- and when wet, the shorted the buttons which are obviously not water proof, so it spend all night turning the leds and laser randomly on and off. battery hold up ok though.)

and this a rack http://www.blackburndesign.com/racks/mtn-2-rack.html (it has a hole on the back, where you can fit a L shaped adapter that holds a reflexive cat's eye)

  • after trying both options from Daniel i'm now considering 3d printing... :/ sucks that there are no standards for those things. Damn all those companies.
    – gcb
    Commented Mar 7, 2014 at 6:38

6 Answers 6


One possibility is to use extra rubber shims to use the seatpost attaching mechanism to attach to the stay of your rack, like so:

enter image description here

You might be able to use something like the Low down light mount bolted through that hole to give you a little bit of post hanging from the hole and use that with the seatpost mount...

You might be able to mount the hardware without the seatpost mechanism to the hole of an L-bracket mounted in that hole...

With racks with a more serious light mounting bracket instead of just a horizontal hole, I've found many light can clip directly to the bracket with no extra hardware at all, like so:

enter image description here enter image description here enter image description here

  • i like the idea of using shims to mount on the side of the rack... but on the last pics above you are pretty much killing the side vision for your rear light
    – gcb
    Commented Oct 27, 2011 at 21:34
  • Also, most racks have that rear mount two screws type. both mine have it. (topeak and blackburn)
    – gcb
    Commented Nov 12, 2011 at 21:49

For a lightweight light that clamps to a seatpost all you need is a piece of pipe of the appropriate diameter and some way to clamp it to your rack. I'd recommend about a 5" length of plastic or steel electrical conduit (though buying such a short length may be difficult). Or a length of wooden dowel will work. Clamping it to the rack will require some ingenuity, but if the rack has a reflector bracket attached you could drill holes in the pipe to bolt to the bracket. If there are only mounting holes for a reflector bracket, you can bolt an "corner bracket" to the rack and bolt the pipe to the bracket.

But another option, for the light you have, is to discard the pipe-clamp portion of the bracket and bolt just the actual mount to something. A short length of aluminum "angle iron" would probably work.

  • The pipe idea is great! but isn't there anything ready made?
    – gcb
    Commented Oct 26, 2011 at 3:52
  • I have done this and it works great. I used hose clamps to attach a short length of PVC pipe.
    – DQdlM
    Commented Oct 27, 2011 at 23:44

If you want something purpose made I know that there are lots of rear lights that come with reflector mounts as included options. For example, here's one from Blackburn.. Look around and read the specs, or ask your LBS for suggestions (there are lot's of crappy lights out there and every shop has their favorite that's proven itself to be durable). There are also plenty ways to rig a light onto the reflector mount of your rack, just use your imagination.

  • not really trying to buy another light... maybe i can go to market with a simple solution like the 1st answer mention, a pipe that attaches to the standard rack mounting hole
    – gcb
    Commented Oct 27, 2011 at 21:33

Cateye seem to have quite a few mounting options for each light on their website, including an adapter bracket for a rear rack, which fit most Cateye lights at least. You can also buy just the mounts without having to buy a whole light, or light set.

Or you could get a light designed to mount to a rack which many of the German ones do like Busch and Muller.
Then you have the no bracket style lights like the ones from Knog that you should be able to mount to a rack.

  • i got lights like Knog's from dealextreme.com for $2 :) Most people, like me, already have lights on seatpost when they buy the racks. So why there's no way to attach the seatpost like lights to the rack?
    – gcb
    Commented Nov 12, 2011 at 21:51

After riding a few weeks with a pvc tube as @Daniel suggested, and another few weeks with the light bolted directly to the rack, I plan on 3D print a $#@!% bracket.


i over did it a little. It is now fully parametrized and can be used with any rear bike rack (just enter the screw you want, the distance from one screw to another, thickness, etc) and any slide-in bike light (chinese, planetbike, etc) just enter the size of the connector part from the light.

Death to proprietary connectors! :D

now i just have to convince myself to pay $12 plus almost same as that for shipping for something that might be too flimsy for any actual use :-/


Planet Bike's small parts page has a section for tail lights that includes quite a few shims and adapters. You may be able to find just the thing there. Good luck!

  • I have no connection with PB except as satisfied customer -- including for a tail-light shim for my not-particularly-standard Electra Townie rack.
    – D.Salo
    Commented Mar 8, 2014 at 22:42
  • The light i have looks like it is planet bike, but it is not. it is just 1mm too deep and 0.5mm too thin. damn china.
    – gcb
    Commented Mar 10, 2014 at 22:48

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