Front and Back
Using larger needles and a provisional cast on, CO 80 (94, 106, 116, 128, 138, 148) sts.
Stripes: Work 4 rows st st in color A, then join color B and work four rows without breaking color A yarn. Carry strands loosely up the side of work. This will help avoid having to weave in ends later.
Do not slip the first st as you work pattern, this will make the edge sts too tight.
Work 17 (22, 28, 30, 35, 38, 38) rows or until piece measures 2.5 (3.25, 4, 4,25, 5, 5.5, 5.5)” Write down the number of rows you worked if they differ from the prescribed number below, so you can make the front and back identical.
Shape body sleeves: On next row, increase as follows.
Increase Row: K1, kfb, work until 2 sts rem, kfb, k1; 2 sts inc’d.
Cont working st st and stripes, working inc. row every 6 (5, 4, 4, 3, 3, 3) rows for 18 (20, 20, 24, 24, 21, 21) rows; 88 (104, 118, 130, 146, 154, 164) sts. Mark this row by securing scrap yarn, safety pins or locking st markers on the first and last st of the row. The underarm seam will end at this point on the finished garment.
Cont to inc every 6 (5, 4, 4, 3, 3, 3) rows. Cont. until you have worked a total of 10 (14, 17, 17, 18, 19, 10) inc’s on each side, 100 (122, 140, 150, 164, 176, 168) sts.
For size 54 only, cont inc every 2 rows until you have worked 10 more inc. on each side for a total of 20 inc on each side (188 sts).
Shape sloped shoulders: [Work to last 6 (6, 5, 5, 5, 4, 4) sts, w&t] twice. [Work to last 6 (6, 5, 5, 5, 4, 4) sts before the last wrapped st, w&t], 6 (8, 14, 16, 18, 24, 28) times. As you work short rows, continue to work stripes. You can either carry the yarn VERY loosely behind (on the knit side), or break the yarn and join it again as necessary.
After the last w&t, break yarn.
With the knit (wrong) side of the piece facing you, join color B at the far right edge and work one row across all sts, picking up and knitting the wraps of the short rows. You can keep the yarn attached and use it to bind off the shoulders later (one less end to weave in). Place sts on a long length of scrap yarn.
Work back the same as front, but leave on the needle.
Bind off Shoulders: Return the front piece onto a larger needle so that when you arrange the front and back with knit (wrong) sides facing (unlike a "normal" three-needle bind off), the needle tip of the back and the front are both pointing away from the neckline on the same shoulder. Usually, you do the three-needle bind off with the right sides facing each other. This time, the bind off chain will be displayed on the shoulder seam of the garment, instead of hiding on the inside.
Using color B, work from the edge of the shoulder/armhole toward the neck with a three-needle bind off, 24 (30, 40, 45, 50, 52, 60) sts each side. Break yarn.. 76 (92, 100, 105, 114, 124, 128) live sts remain on each needle.
Repeat for the other shoulder edge, working three needle bind off from the shoulder toward the neck.
Finish neck edge and create ruching: Starting at one neck edge (this will become the back piece), bind off as follows, K1, *k1, slip first st over the second st*, repeat until you have worked the 52 (62, 60, 60, 64, 72, 80) back sts. Continue binding off the first 8 (10, 10, 10, 12, 12, 14) sts of front, then ruch.
Ruch: Pick up 1 st 8 rows directly below and place on left needle, pick up second st 8 more rows below and place on needle, pick up a third st 8 more rows below and place on needle, then knit through all four sts and bind off. Repeat 5 more times. Cont. to bind off 24 (30, 28, 28, 28, 36, 40) sts, then ruch again for 6 sts. Bind off the remaining 8 (10, 10, 10, 12, 12, 14) sts and tie off.
Side Seams: Thread a tapestry needle with color B from the ball, do not break yarn, work mattress stitch from the markers at the armholes toward the provisional cast on. When the seam is complete, you can use the end coming from the ball to work a single crochet into each row st of the armhole, purl (right) side facing you. Make sure you catch the floats from working the stripes.
Ribbed Hem: Using color B, place provisional cast on sts on smaller needle, join for working in the round and work 1x1 ribbing for 75 (80, 80, 85, 85, 80, 80 rnds or until piece is the desired length.
Note that the bamboo yarn is drapey and tends to grow, so you may want to fully wet and dry your piece, still on the needles, before you bind off.
Bind off using color A, using Stretchy Bind Off: [K2tog, slip st on right needle to left needle] repeat to end, then pick up and knit the first bound off st, slip over the remaining st, cut yarn and pull through. Weave in all ends.