I wasn't sure about sizing and went with the suggestion of many reviews to size up from what you normally would get. I'm also new to wearing an aero type jersey and much rather perfer the mtb style shirt. My dims, 210 lbs, 5'11" with some fat around my stomach and athletic build elsewhere. Jersey choice, I find size large shirts fit nicely on me and a little better when shrunk some. I went with a traditional XL and was happy with my choice. Even with the roomier design, I felt everything was snug.and probably added some motivation to work on my core. Note.. when I'm in the hoods, I notice that the front bunches up a little around my stomach. Not to the point where I am annoyed but probably a result of my body type and the roomier style jersey. I feel like the moisture wicking is great and fabric feels comfortable against the skin. Will be trying a base layer and then the Aero style jersey in the future. Thanks Pactimo!