The Flyknit Racer is intended to give a snug, sock-like feel; almost like that of a track spike. Because of this, you will want to go true to size. The fit is also quite narrow and there is no wide option available, so those with wider feet may need to upsize, though this defeats the purpose of the close-fit. The shoe is intended to be unisex, so women will need to downsize to find their ideal fit.