The CapoForma Phantom Tactel Socks might hide beneath your cycling shoes' cuffs, but they don't slack when it comes to wicking sweat off your hard-pedaling feet. Elastic in the arches provide support and a snug, no-wrinkle fit.
Really low profile - if you chose the sock that has the same upper color as your shoe, then I bet people would not even realize you were wearing socks. Quite thin, so if you rely on your sock for comfort/vibration damping (say with a really thin or sub-par insole... cough Sidi) you may feel it in your feet. As a size 9, I am at the low end of the Large size, so it is just a little big, but I would assume the Medium would be too tight.