[Dean]

The head of some safety pins is a bit big and the pins too wide to thread easily. I find it easier to use a hair-clip, but one where the ends are well rounded. The shaft that you are working with is longer but thinner, which is much more satisfactory. One does need to double the cord over carefully otherwise the end of the cord slips out.
Byron, the shaft you are working with looks like a good length to reach across the black stripes, you should have no problems. The whole idea of a safety pin though it that it has a protective head to guard the pointed end and keep it safe. It seems from the photo that you have removed your protection. Need to be careful it does not damage the cloth in that state.