I think the fabric is too light weight and stretchy.

If you can iron it, you could try ironing on a strip of light weight interfacing right where you are going to sew. Pin your hem then pin a half inch lower then iron the interfacing on to the pants. That will give you a firmer base to sew on and if it's light weight it shouldn't add too much stiffness or bulk.

If you've cut some off the bottom you could give it a trial run

I generally call it decorative. I'm not a type A personality, though.

You mention adjusting the tension: needle or bobbin? It would be the bobbin tension that would help you here. Try loosening the bobbin tension, maybe a little more than you think necessary, and see if it makes a difference.

They're exercise pants? You'll be moving, yes? If someone's checking your hems while your exercising, something is wrong with the whole setup.

Thank you oilpainter and evaf555.

I was so focused on the machine that I didn't even think of using some sort of stabilizer (hits head with hand).

I have two pair of these pants. On the first pair I used a zigzag stitch and the wrong type of needle. The thread kept breaking - what a mess. So the second pair will look better no matter what. It's true I'm the only one who will notice. I'm probably just looking for excuses not to exercise. :)

I can't find how to change the bobbin tension. A closer reading of the manual is in my future.

Susan

I agree with loosing the tension or lengthening the stitch, usually doing one or both should help. I do not mess much with the bobbin.

I often use wooly nylon in the bobbin, sometimes for the upper thread also, it has a stretch.

I believe the fabric is called sport knit mesh, I press in the hem, sometimes light spray starch/sizing or stabilizer spray.

Did you know that they now have twin needles that are ballpoint. Ballpoints usually are used on knits.
HTH

Patti, is a stretch needle the same as ballpoint? I'm using an Inspira twin stretch 4.0/75.

Sport knit mesh describes it perfectly.