Sidis do run really small. I wear a 7 in most street shoes, and my Sidi road shoes are a 39, which I'd say is a 6.5; they fit, but just barely -- fine for road shoes since my feet jam back in the heels when I ride, but I wouldn't want to walk in them much! If I ever buy another pair of Sidis, they'll be a 40. My Pearl Izumi Vagabonds (mtb shoes) are a 38 and have a lot more room in the toes and are longer than my Sidi 39s! I don't know why Sidis are sized so differently from other bike shoes.

Emily