- You get all the tricky math and counting out of the way at the beginning of the sweater.
- You can try it on as you go. If it's not going to fit, you find out almost immediately and can rip it out and start over without a backwards glance.
- The sweater grows organically, with shaping integrated into the knitting through the use of increases, decreases, and short rows.
- You don't have to guess about body or sleeve length, but can make the sweater as long as you like. You can adjust sleeve or body length to available yarn.
- You can easily lengthen or shorten the sweater, an especially handy feature if you are knitting for children.
- You can easily replace cuffs and ribbing, the parts of the sweater that get the most wear.
- You don't have to sew any seams. Most edges are eliminated and the rest can be picked up from existing knitting.
I've presented options for working top-down: raglan, round-yoke, or shoulder-down. I then complicated matters by presenting the most complicated kind of raglan, the poncho sweater, as an unspecified fourth option.
All top-down sweaters, however, start from the back neck and shoulders and work down the yoke to the underarm. At the underarm, the sleeve stitches are divided from the body stitches, and extra stitches are cast on to form an underarm gusset shared by sleeves and body. These extra stitches are incorporated as the body is knit down and later picked up and knit as part of the sleeves.
The body is knit down from the underarm to the bottom edge. The sleeves are also knit top down to the wrists, decreasing as you go.
About a third of the knitting (and about a third of the yarn) is in the yoke of a long-sleeved pullover, about a third in the body, and about a third in the sleeves.
The yoke of the sweater is responsible for 90% of the way the sweater fits. Almost all of the complicated knitting and shaping is in the yoke. If you can get the yoke to fit well, you can do almost anything with the body and sleeves and the sweater will still fit the wearer.