A flattering fit is especially important in a pant. We spend quite a bit of time searching for that snug, derrière-hugging fit you find in jeans. Trousers are a whole different story. They are a more formal pant with a smooth line and fluid fit. It’s jeans, and the casual pants like them, that cause us to spend hours trying on pair after pair. No one wants a saggy bum. So here’s the trick: If you look at the pattern piece for a pair of these types of pants, the back inseam seam ends up on the bias. With this fit trick, we are going to exploit the bias’ natural stretch.
Once your pattern piece is cut you are going to pin the inseam together from the bottom to the knee. Then clip about an inch off the top of the back inseam at the crotch. CLIP ONLY ON THE BACK. We are not looking to drop the crotch, so we need that front inseam to stay put. Clipping the back crotch seam will make the back inseam shorter than the front. Not to worry, this is a stretchy seam, and we are going to make it act like a bias cut dress.
Now that you have clipped away the back crotch a bit, grasp the top of the cut seam only, and the seam at knee, and stretch just this portion so that the top edges meet again. Continue to assemble your pants as usual. Voila! A snug, sexy, flattering derrière through clever use of bias! Now go make a pair. Happy sewing, and happy head turning!
Basic pant pieces as they start
Basic pant pattern. You can easily see that the inseam is on
the bias, if you look at the stripes. The cutting line goes diagonally across the stripes. If you pull lengthwise on the cutting line, the fabric will stretch. This is true of pretty much all weaves: Plain, like shown, or twill, like denim. Twill is exceptionally stretchy. That’s good for jeans. Not so good for corsets.
Crotch seam trimmed away on back inseam.
On the BACK ONLY, trim away about a half inch from the curved edge, smoothing into the curve that’s already there. Here you can see the back crotch seam trimmed away, and the new curve of the center back seam.
Back inseam stretched back to its original length.
Now pick up the pant back pattern piece at the knee and at the point where you trimmed away, and firmly pull until it matches the front piece. This is the only area that you want hugging your leg. It will have the best stretch here anyway since the bias goes away at about the knee anyway. This whole bias thing is due to the width of your thigh being wider than your calf. A slim fit pant will follow that shape closely. Now it will fit closely all the way up. Yeah!
From here on, assemble the pant as usual. Those of us that like to experiment can make up the pattern both ways and and see how the fit changes.