You can fill them with clothes, gather the ties to close loosely, hold the bag mouth so just a small opening exists, and lean/press all of the air out...
Tie the mouth close securely by wrapping the ties around the neck a few times...
Thanks! That would probably work if I had a large suitcase, but if it won’t fit in the overhead bin, it’s too big for me to wrestle with. Which is why I chose Space Bags — some are quite small, and fit in the small suitcase perfectly.
After my trip to CO last summer, though, the wheels literally fell off my American Tourister bag, so I had to get another. The new one is a bit smaller but has hard sides and the casters roll in every direction.
This trip will be to road test for the new bag!