All it is, is a piece of plywood with a bolt through the middle to hold the camera, and straps as an extra precaution.
Not including the plywood (which was scrap I had lying around) or the bike rack, the rig shouldn't cost more than a few dollars.
You can see the final video here (here's a link skipping to the shots done with the rig)
Step 1: Materials
-Your camcorder (you'll need this to check the dimensions and positioning of various aspects of the project)
-Three or four feet of 1" wide webbing (the size an shape of your camera is going to affect how much you need, but I only needed about three feet total)
-One for the webbing
-One bolt (1/4"-20, coarse thread. The bolt I used was one inch long)
-A bag of zip-ties with a 75lb load limit (feel free to go higher, but I wouldn't go lower because they can take a beating when they get shook around on a bike ride)
The above picture shows more materials than I ended up actually needing, so pay attention to the list here.
And for tools you'll need a jig-saw and a power drill, as well as a bike rack to attach the rig to.
Step 2: Cutting the Plywood Base.
Step 3: Drilling the Zip-Tie Holes and Installing the Screw
After that, find the center of the board and mark it. This will be the location for the bolt.
Drill all the holes on the sides, and in the middle. For the middle you want the hole to be just big enough for the bolt so that it fits in tight (I had to hit it to force it through). And for the sides, you can choose a drill bit slightly larger than the zip-ties' width.
After all the holes are drilled you can place the screw into the center hole (it should be poking out through the top as this is where you'll mount your camera).
Step 4: Holes for the Webbing
Mark a pair of holes just inside of each line (in the picture there's only two pairs, you should have four in total), the holes should only be a little bit farther apart then an inch (the width of your webbing).
Drill all of the holes. Then, using a jigsaw blade small enough to fit inside the holes, cut out gaps between the pairs of holes.
Step 5: The Straps
Once you've figured out the length, cut the webbing and use a lighter to melt the ends a bit (this will keep it from fraying). Run the webbing through the sets of holes and then your rig is finished! All that's left to do is mount it to your rack.
Step 6: Attaching and Using the Rig
To mount the camera, screw it as tight you can onto the base and position to face either backwards or to one of the sides. Then pull up the corresponding strap, and tighten it with the webbing buckle by threading both ends through one hole and then down through the other.
Make sure to tuck the unused webbing under the board so it doesn't fly around in front of your camera when you're using it.
Please leave any suggestions for improvements in the comments thread, enjoy and thanks for reading!
CAMERA SAFETY TIPS:
-Make sure you be extra careful when mounting and un-mounting the camera, you'll want a firm grip on the camera because it can come off unexpectedly as you're unscrewing it.
-Make sure you have a sturdy rack.
-Don't mount the camera and then just leave the bike unattended, who knows when it'll get bumped and then your wonderful camcorder will come crashing into the ground.
-I tested this on some fairly bumpy ground, and it held on tight, but you are still risking your camera by mounting it to the back of a bicycle then riding around and risking falls. You also might want avoid subjecting your camcorder to excessive vibrations.