i've got 3 pair of Sidi cycling shoes in different sizes; old Dominator 2s that work perfect without socks in 45.5, Dominator 5s in 46, and Carbon Titanium road shoes in a 46.5.
i found that i needed the Crossfire 2s to be larger than all of those and didn't fit right in anything smaller than a 47.
bottom line; if you don't have the chance to try them on in person, be prepared to return/exchange them, or order a couple of pair and return what doesn't work.
just a guy...
'02 GS Adv