Originally Posted by
Digital Gee
So can anyone answer my original question?
Yes. It's one of those Murphy's Law things. If the sweats are borderline too small, washing in hot water will make them shrink uniformly. If they're a little too big, such washing will shorten the legs but expand them around the waist and butt.
Fortunately, you now have some excellent material for making bike washing rags. That's important for keeping your white bike spiffy looking.