Help!....making sense of shoe sizing, gulp

[emily_in_nc]

I wear sz 7 and my new Lake CX170s are 39s. My foot is a little bit wide. But this may be the first pair of cycling shoes where I don't need arch supports.

HTH

I also wear a 7 in street shoes and used to have a pair of Lakes (not sure what model, a much older one) in 39. I have narrower feet. I bought a pair of Sidis in 39, and they were too short (but not too narrow), but I have since heard that Sidis run small.