Leg Hole Design

Why does it matter where I put the leg line?

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Good morning class. I hope you all read chapter three last night. We're going to have a pop quiz.

Look at each of the leg line designs below and tell me which one you think is the most stable. If you're really keen for bonus points then rank them in order from most stable to least stable. By stable I mean how well the design will stay where it's supposed to on the body.

 Well the apex forward of the side seam is the most stable as it doesn't interfere with the leg and hence doesn't mess up the fabric. And the front panel from the waist can draw a line down the back leg line holding it in place.

The hybrid apex on the side seam is the next most stable for the same reason. Essentially if you follow the angled back line up a bit more you really still have an apex foward of the side seam, just higher cut ... it's a trick question.

The angled apex at the side seam is popular because it looks like a higher line but it does put fabric over the leg. It does create a stronger elastic line in the front which is then prone to loosing that tension rapidly in the front on bunching up (not increasing tension add you might think) ... a tension that is the only thing holding a narrower back panel precariously in place.

The curved side seam is a disaster because of how the elastic lines up with horizontal negative ease ... let me explain ... The curved apex stagnates the tension in the elastic when on the side seam ... a dead zone of sorts on the front panel now cant help to stabalise the back ... so all the forces in the back are vertical ... garment gets eaten by bum. This dead zone is created because the elastic is parallel to the horizontal negative ease for a few inches ... it literally opens the curve at the apex. Does that make sense?

Why doesn't this happen at the apex forward of the side seam too then ... The top of that is curved right? Well it does ... but the front panel around the waist can still draw a line down the back leg line (anchoring it somewhat) ... This line is cut when the apex is on the side seam so the back leg line just collapses.

Question from Morrison Jackson:  And how do we help the back stay in place and not pull up into the crack?

Answer from Me: many ways ...


  1. Wider back panel/more cheek coverage

  2. Center back seam

  3. Apex forward of the side seam

  4. Lower leg line

  5. Move the side seam forward below the waist ... you're changing fabric grain (if you can call it that) at the seam line to more on grain at the back and more off grain at the front. Keeps the front a bit stronger infront of where the side seam previously sat ... only about 2 to 3% but it does make a difference!

Question from Georgia Fellows:  Surely apex forward from side seam would be most stable. The leg bends forward from the hip but not backwards. If the leg line cut across that point it would just scrunch up where the leg naturally bends (maybe).  I imagine if the apex was too low over the leg, the elastic would stretch to sit where the leg naturally bends withe the fabric bunching above this, causing horizontal ripples. Please guide me if I’m completely off track 

Answer from Me:  the elastic stretches below and shrinks above because of the bunching ... elastic doesn't like that ... The loss of tension above destabilizes the back suddenly then the panel moved inward to butt crack and when the leg goes down releasing the elastic to even out again it snaps the back elastic upward and plants the garment further inside the crack ... you can actually watch it happen when girls stand up bent over then straighten up .... "The two stages of hungry butt" ... not a good look.

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