I did a lot of research before buying bicycling shoes because I found out the sizing chart for these shoes is a little bit odd. I followed the reviews on Giro Factress shoes and Giro Solara before buying the Giro Sante shoes. I usually wear 8.5 in US size for all kinds of shoes and the size chart said that I should order 40.5 in Giro shoes. Having in mind that I tend to have wide feet (only a little) I ordered one size up for these shoes (41.5 ) and they fit perfectly like a glove. I tried them with my thin socks that I also ordered and they are very comfortable. Of course you cannot walk a lot around with these shoes because they are designed to use while you are in your bicycle but overall I could say they are comfortable and breathable. Keep in mind order one size up.