I am thinking of redesigning the bike shorts pattern I've been using. The crotch seam is a problem, even if you put the seam allowance on the outside. For me, anyway, it seems like that seam is rather irritating after a while because it fits so tightly. Maybe, as I said, this is a girl problem, but it's a problem. I am thinking that you could make some sort of "codpiece" (ironically, since I'm fixing a girl problem): a sort of panel that goes down the front and through the crotch and up the back. That way, there would be no seam at the center. Has anybody ever bought bike shorts like this or used a pattern like this? I'm not sure exactly how you would sew it on a machine. This modification might make bike shorts better for men too.
Alternatively you could make a square gusset at the crotch, like the ones that tights often have.