Finally, just bungee the unicycle on tight, and ride away! Be warned, this may be dangerous, so take care. I also carry a lock to lock the uni to my...
How to build a unicycle rack for a Harley Davidson motorcycle. Don't let riding your motorcycle stop you from riding your unicycle! Supports both a 20" trials unicycle, and also a standard 24" mountain unicycle.
Step 1: Cut up an old bicycle
First off, you need some steel. I used an old bicycle and cut it up with a sawzall. After cutting the steel into manageable lengths, it is a good idea to remove the paint.
Step 2: Figure out where to mount it
Figure out a good spot on the motorcycle to mount the rack. For my Harley Sportster, that was on the rear shock mount. Heat up the end of one of the tubes with a torch and flatten it it out on an anvil. Then drill a hole that will allow your bolt to pass through
Step 3: Weld a simple square together
Basically, you are welding a simple square together. Mount the two pieces you cut in the previous step to the side of the motorcycle and cut a piece that fits in the middle. Cut it off at a 45 degree angle and weld it together.
Step 4: Weld a vertical post to the top of the square box
Next, you want something to hold the frame to. So, take a piece of tubing and cut a semicircle on it. I used a dremal, which isn't the easiest way to do it, but works. Weld the post vertical, and test fit the unicycle to it with a bungee cord.
Step 5: Weld on a horizontal post
Next, you need to find the good spot to place a horizontal post. To make it work with a 20" and a 24" uni, I had the post just above the tire on a 20", and just below the rim on a 24" (going through the spokes -- see the last picture). After you find the sweet spot, cut the two posts to fit at 45 degree angles and weld them together. I had the angles with the horizontal tube pointing slightly upward to hold it together a little tighter.
Step 6: Weld on some nubs for bungee cord attachment
Finally, weld on some nubs for bungee cord attachment. I made these by bending some steel over in half, and then cutting the resulting half circle out.