I was under the impression the small would be a tad bigger than a normal small which i was understood it to be after the research, i'm normally a medium in clothing. I've wore it anyway and although i did sweat in this it wicks away moisture pretty quick. i was riding in 35 Deg here in Australia. After the ride once home the T-Shirt smelled normal no odour smells from sweating in it. Would buy another but get a medium, quality is good as you would expect from Rukka.