Quick fix: If the ribbing cast on is tight, rip it out and recast using a larger needle (2 sizes up). If the bind off is tight, rip it and redo it with a needle 2 sizes larger or use a sewn bind off.
What you are seeing
Ribbing that should stretch to fit over hands or a head but sits stiff and narrow. The ribbing may look correct — alternating knit and purl columns — but it cannot expand when pulled. A finished cuff or neckband may be impossible to put on.
Why it happens
- A too-tight cast on that anchors the ribbing at a narrow width
- A too-tight bind off that restricts how far the top of the ribbing can expand
- Knitting the ribbing at a tighter gauge than the pattern intended
- Using a non-stretchy cast on (backward loop, cable) for a ribbing start
Fix it now
- Test whether the cast on or bind off edge is the restriction: hold the ribbing and stretch it. Which edge resists first?
- If the cast-on edge: rip back to it and recast using a needle 2 sizes larger, or use the German twisted cast on, which is naturally very stretchy.
- If the bind-off edge: tink the bind off and redo it on a needle 2 sizes larger, or use a sewn bind off (thread tail through each stitch purlwise then knitwise, loosely).
- If the ribbing body itself is tight: wet block the ribbing — soak in cool water, stretch to the needed width while damp, and pin on a foam mat. Wool and wool blends respond very well.
Prevent it next time
- Use a stretchy cast on (German twisted or long-tail thumb) for all ribbing starts.
- Bind off on a needle 2 sizes larger whenever the edge must stretch.