Knit one, purl one ribbing is so common in knitting, and while you can use virtually any cast-on technique in any book to get started, tubular cast-ons are my preferred choice for ribbed edges. Why? There are two main reasons:
A tubular cast-on is stretchy!
Ribbing is added to the edges of garments to provide some stretch. It's certainly not necessary, but it does create a nice, gentle blousing effect on garments that are primarily Stockinette stitch. It keeps socks up around our calves (mostly) and keeps cold air from sneaking up the arms of our sweaters. A regular long-tail cast-on works just fine, but a tubular cast-on is incredibly stretchy, making it even easier to pull a knitted hat on our head—I'm sure most of us have run into the "ooops cast on just a bit too tight" problem. No such problem with tubular cast-ons (making sure you cast on the correct number of stitches is a different problem).
A tubular cast-on provides a beautifully clean edge to ribbed fabric.
Ashley Rao's article in Knitscene Winter 2013 is called "The Limit Does Not Exist" for a reason—there's no harsh cast-on edge to tubular cast-ons. The edge of the fabric blends gracefully into the ribbing and adds a polished touch to the fabric.
If you're participating in the Tara Jacket Knit Along, Ashley uses the second method she mentioned in her excellent article to cast on for this knitted motorcycle jacket. However, the jacket pattern starts with a purl stitch—the method in the article demonstrates beginning with a knit stitch.
There's a note in the Stitches section that describes how to start the cast-on with a purl stitch instead of a knit stitch, but I thought a couple of photos might be handy.
With contrasting waste yarn and using the backward-loop method, cast on half the number of stitches required plus one (total sts + 1, divided by 2). Cut the waste yarn. With main color yarn work as foll:
Row 1 (WS) K1, *yo, k1; rep from * to end.
Row 2 Sl 1 pwise wyf, *k1, sl 1 pwise wyf; rep from * to end.
Row 3 K1, *sl 1 pwise wyf, k1; rep from * to end.
Rep Rows 2 and 3 once more.
Next row (RS) P1, *k1, p1; rep from * to end. Cont in p1, k1 rib as established, removing waste yarn after a few rows.
I'm particularly partial to the third method from the article, and I used it when casting on for my Bristlecone Pullover. Allyson Dykhuizen's pattern doesn't call for any specific cast-on technique, and that's the great thing of being a knitter and making your own things—you can choose to use whatever cast-on technique you want!
I hope you'll give these different tubular cast-on techniques a try, since it never hurts to add to your knitting technique arsenal! And for even more awesome cast-ons (and bind-offs), download Ann Budd's 45+ knitted cast-ons and bind-offs video.
Until next time, happy knitting!