I am having this same question. My husband always tells me that my cycling clothes are too loose. (He says that about all my clothes; I think he'd be happiest if I could find a way to walk, hike, bike, and paddle in some sort of fancy wicking corset and heels.) I usually wear size medium Pearl Izumi shorts, and I think they are fine, but he thinks they are a little big on me. I just tried the Shebeest Triple S shorts in small, and they feel a bit too snug. I have a tiny bit of bulge around the leg openings (but they are otherwise fine). Going by size charts, the Shebeest medium is a bit larger than the PI medium, so I'm not sure what to do.

Maybe I'll just stick with the PI's.