My favorite winter riding costume is 3 layers of wool sweaters, topped off with this fantastic vest that my husband got me some time back. It keeps my core toasty, it’s got plenty of pockets, and it’s got a cozy fur-lined hood.

It’s also got two problems:

1) It’s black. I’m not a huge fan of hi-vis neons (and wearing a neon vest with lots of blinkies certainly didn’t keep that King County Metro driver from sending me to the pavement back in April), but I do want to be safer.

2) It was not designed for a woman who wears larger than an A cup. Dear lord. It fits me great at the hips and waist, but I seriously could not breath if I zipped it past halfway.

Through talking with friends (and personal experience), I know that point 2 is a common problem for a lot of women with ready to wear clothes. Especially vests, for some reason.

I know how to do a Full Bust Adjustment on a pattern before sewing it, and I thought surely there must be a way to do a FBA on a garment that’s already been made. I finally settled on the idea of inserting stretchy panels in the side seams from the arm hole to just above the waistline.

What. Sweet. Relief.

It was also way easier than I thought, so I thought I’d share my process in case any other ladies out there would find this helpful.

(Oh, and since I had my vest near my sewing machine, I thought I’d fix its visibility problem with a little reflective flair. It’s pretty awesome, if I do say so myself.)

You need:

A small amount of ribbed knit fabric in a corresponding color.
A seam ripper
The usual sewing accoutrements

Step 1: Preparation

Try your offending vest on and decide just how much more ease you need for the girls to breathe. I decided on 3″.

While you’re wearing it, find the waistline and mark it with a pin in the side seam.

Step 2: Marking

Measure up about 1 1/2″ to 2″ from your waistline. Mark that spot on both side seams.

If your vest is lined, find that spot on the inside. Oddly, my lining side seam and shell side seam didn’t match up inside. I decided not to worry about that.

Step 3: Open the seam

Carefully unpick the side seams from the armhole down to your mark. Be patient—it can be tempting to just run your seam ripper through the seam, but the nylon shell of a vest like this slices so easily that you may not even notice until you’ve cut a big hole in it. Especially if you have a sharp seam ripper, which you do, right?

If your lining seam lines up, then unpick that one, too.

Like I said above, mine didn’t. My vest is lined in a dense fleece that won’t unravel, though, so I opted just to cut it open from the arm pit to my mark. Because it won’t unravel, I didn’t bother finishing the edge—but if you have a lining that will, I’d do something like use a bias binding, or just zigzag or serge it.

Step 4: Insert your stretchy panel

Cut your ribbing:

Length: (Opening length x 2) + 2″
Width: (Total ease desired/2) + 1″

You’ll fold it in half lengthwise, so make sure you cut it so that the ribs are going the long way.

Insert the panel into your side seam and pin it in place, folding under the shell’s seam allowance so it looks neat. Make sure you have the lining pinned perfectly, as well.