If you're torn between rs and rse, I think the rse chamois is just that much better and the shorts seem more breathable. I rode a 500 mile trip last summer over 7 days and the day I wore the rse was by far my most comfortable. Pay the extra money for the rse, you won't be sorry. Also for sizing, they are true to size, don't buy "up" a size. The legs are supposed to be snug for the benefit of compression. I'm 5' 8" and 120-ish and I wear the small. The mediums swam on me.