It is unfortunate that the sizing link brings up some generic sizing info. Go to 2XU's website for sizing. For people who have not used any type of compression gear, these are supposed to be really tight. Compression shorts, calf sleeves, etc are often so tight that they have to be rolled on or slowly inched up onto your body. These will not fit like normal Lycra shorts or bike shorts. At 5'9" and 140LB I find that the small size fit perfectly.