This Instructable will show how I built a bracket that allows me to attach seat post mounted lights to the back of my bicycle's rack.

After researching to find the best rear flasher, I decided upon the Planet Bike Superflash. Unfortunately, it's designed to be mounted to the seat post, or by using a clip, to a saddle bag, backpack, or anything with a loop. The clip on the Superflash isn't strong, as some reviewers of the product write. Also, the Superflash does not have a screw for mounting to a rack.

I use a rear rack on my bike to mount pannier bags and the occasional package. I also use a saddle bag to carry a tool kit, cellphone, and other necessities. With all of this stuff on my rack and under my saddle, mounting a light on my seat post isn't an option.

My rack has a tab on the back where I can mount a light or reflector using a single screw. Using a handful of spare parts, I was able to construct a bracket that extends from the back of my rack and provides a tubular structure where the seat post mounted light can be attached.

Step 1: Gather Your Tools and Supplies

I used the following tools and supplies:

PVC pipe that approximates the diameter of a seat post
Seat post mounted rear light
Hex key/Allen wrench set
Metal brackets or any scrap metal that could be bent into desired shape. Note: hardware stores carry metal straps that have holes pre-drilled in them.
Hacksaw for sawing the pipe and bracket
Drill or knife for making holes in the pipe
4M hex screws with split lock washers and wing nuts

As luck would have it, I found a piece of PVC pipe on the side of the road. All I had to buy for this project was a handful of screws, nuts, and washers.

Note that I don't have my Superflash yet. I'm substituting my current Trek Flare 7 light in the meantime.
this is an awesome idea!! now i'm wishing I kept that bit of seatpost that I hacked off my bike a couple of weeks ago! :P
Thanks very much for this, I'll be trying it out very soon. I will however make one small modification. You say you couldn't have it tight in case you broke the PVC pipe, so perhaps it would be better to shape the pipe by cutting a strip off the top at the back and gluing on a flat piece of PVC, so that it is the flat surface that is in contact with the rack, allowing you to securely attach it. Or to save the hassle of solvent glue, use a piece of wood and do the same.
After my first test ride it was obvious that the bracket was moving up and down too much every time I hit the tiniest bump. It even threw my light off of its mount. I used two little zip ties to lash the bracket to the back of the rack, and so far, it's making a big difference in keeping the bracket steady.
Great Instructable. I lost my rear reflector by using a crappy mount. This one seems infinitely better.<br/><br/>As a note, I would remove all the photos except the first two on the Intro step. On some pages (and maybe only for some people), viewing photos on later steps won't work unless that photo is active in the Intro. If you use a photo in a later step, it might be a good idea to remove it from the Intro.<br/><br/><a rel="nofollow" href="https://www.instructables.com/community/Cannot_View_Images_in_an_Instructable/">Image Bug</a><br/>
Thanks Germy. I was up too late writing this and not sure why I thought I needed to put all photos there. I just uploaded them all at once. :) I don't know if all racks have a place to mount a bracket, but I am sure using P-clips one could rig up something.

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