Now I decided to do this after-the-fact I made this trainer. So the pics aren't that detailed and step-by-step, but it's really simple and I trust you can do this rather easily. So, now...what you'll need:
1- 12" piece of PVC 2" in diameter
1- worm gear stainless steel pipe clamp to fit around PVC
1- length of rope about 4'
1- swivel clip