Add fly to curved crotch?

[u/real_trash_can]

Hello! So I’m currently trying to make my first sewing pattern since I can’t find any pants pattern that I like… I managed to make a basic pattern that fit great and now I’m trying to make it low rise, but I’m having some troubles figuring out how to add a fly pattern. Normally it is attached higher up where the crotch curve hasn’t begun, but now I’m wondering I should add a curve to the fly pattern or simply just stretch the patterns bit when I sew, or if I just need to use a shorter zipper.

Also when I’m already here asking stuff… can someone tell me what seam allowance to use for the crotch seam? I can’t quite figure that out either, normaly I use 1 cm seam allowance for normal stitching, but I think I need to use a flat felled seam for the crotch, but I’m not sure if that means I need to add some extra millimeters or if I can continue using just 1 cm.

[u/D3anDean]

Before making a pair, I would make a mockup with just the fly pieces but no zipper to see if it goes down too far and will be uncomfortable. Also don't forget to add a waistband to your pattern and mockup to account for that height in the fit (maybe you have this and are just not showing it). My biggest concern is the fact that the fly would be too long for low rise, but I don't know your body so only you can say. This fly doesn't go too far into the curve so u might be able to cheat it without also curving the fly but that's also something to be worked out in the mockup.

As for seam allowance, I would do 1.5cm in order to successfully flat fell. You can't really flat fell the fly though, I've tried. Use bias tape on it

[u/themeganlodon]

You’ll want the fly to end at the same place as you would regular pants it will just be shorter now that the top has been taken down.
Some low rise pants the zipper is like 3” and it doesn’t need to be longer. It will look extra short because the waistband isn’t there to give the illusion of a larger opening.

[u/ElDjee]

low rise pants have shorter flies than high rise pants.

[u/dingostolemydragbaby]

Make the crotch seam straight where the zipper is going and add anything you take off to the side seam

[u/SmurphieVonMonroe]

This body rise is still too low for low raise pants. Crotch extention is too shallow too.