I often have issues with sleeves being tight on my upper arms when the shirt fits me otherwise, both with short-sleeved cycling jerseys and regular shirts. In fact I think all of my short sleeved cycling jerseys are size large.

I followed the instructions - measured 11 inches, based on the chart either a small or medium would fit, so I went with the medium figuring small might technically fit but would be more likely to be uncomfortable. And the medium fits me fine. It's snug but not skin tight. Not constricting in any way.