This is my first Instructable, feel free to comment.
Step 1: Parts and Tools
Segment of chain-link fence tubing (PVC pipe would've been much easier if available)
2 Chainlink fence tensioning brackets
2 Locking wire pins (about $3.50 each at Lowe's, in the same cabinet as Clevis pins)
Dog (gotta have a good distraction)
Step 2: Measure twice, cut once
Step 3: Hammer it, bend it, make holes in it
Next, measure the diameter of your headset and seatpost. Mine were about 1-1/2". Leave a little extra room and bend the flattened tensioners into a nice U-shape. I used a vice and shovel handle to keep the bend from getting a point. Wrap them in electrical tape if you want to protect your expensive bike parts.
Don't forget to cut the tape out of the pre-drilled holes in the tensioners. Your pins will go through these