In case you would like to try it too, I've made a mini tutorial here on the blog. It assumes prior knowledge of herringbone stitch and twisted herringbone as I haven't included all of the steps to start you off.
I started off with a regular twisted herringbone rope in all size 11 beads to get comfy, and then began adding my twin beads to it. This is a three spine piece, so there are six beads around total. So, coming down through one 11 and up through two 11s for the rope so far...
Pick up one twin bead (or Superduo bead) and two 11 beads. Go down through the second hole in the twin bead and down through the second 11 in your spine. Go up through two 11s in your next spine. Repeat this twice, and step up by coming up through your two 11s and then the twin and the first 11 added in this round.
Pick up one twin and two 11s and come down through the second hole in the twin and the 11 underneath it. Come up through the first hole in the twin bead in the next spine, and the 11 above it. Repeat around. When you step up, you will be coming up through a twin, an 11, a twin, and an 11.
Just keep on going, adding a twin and two 11s per stitch, coming down through an 11 and up through a twin, and your rope will spiral nicely!
I went back to the start and took off the beginning spiral in 11s, so that the whole rope bracelet was in twins, but I can see how this would look fabulous as a center for a rope, with regular or twisted herringbone in seeds to show off the twins in the middle. :) I finished off each end by adding one 11 per stitch - so that I had a picot of sorts on the ends of the spines, and then went round those three 11s in a circle to cinch them up, and then added a crystal rondelle and a clasp half. Once the crystal and clasp were attached firmly, I came back down to my circle of three beads and added one 11 between each of them to make it look less pointy, and voila I had a bracelet!! I hope you have fun if you decide to try this out too!