There are several possible approaches to knitting a helical strip. We formulated the one presented here to be adaptable to different patterns. See Conway et al. [1] for a simpler stockinette-only method.
The overall approach is to cast on using an auxiliary yarn, knit the first two rows in a similar manner to normal circular knitting, then pull out the casting-on yarn and knit the third row into the bottom of the first row.
1. Using a circular needle and the casting on method introduced in the instructions for transverse strips, cast on enough stitches to fill half the needle. This starter row will be pulled out and discarded, so to avoid confusion use a different yarn with a contrasting color to the main yarn.
2. Slide the stitches to the left needle point, switch to the main yarn and knit a row.
3. Slide the stitches to the left needle point. Wrap the needle into a double circle, so that the two needle points and the midpoint of the needle (where the last stitch is located) are all in the vicinity of the same point. Knit a second row.
4. Slide the stitches around to the left needle point. Start pulling out the contrasting yarn and picking up the stitches onto the left needle point. Continue all the way around.
5. Start knitting the third row. The needle is now running
along the entire edge of a mobius strip. Continue knitting until
the strip is of the desired width. Bind off in the usual manner.
