I forgot to mention that another reason to upsize since bike shoes tend to be snug is to accommodate heavier socks in winter. I wear Woolie-Boolies with adhesive chemical toe heaters in winter and find that a lot of room in the toebox helps for those, too. If my toes are crammed tightly, my circulation isn't as good and my feet get cold quicker. Also the chem toe-heaters need some oxygen to work. In summer w/thin socks my toes appreciate the extra wiggle-room and ventilation.

I believe the recommended Euro size (per LBS and Colorado Cyclist's chart) for my size 6 1/2-7 feet was 37.5-38. Although I wear 39 now in Carnac and NW, my Sidis were 40 and, as noted previously, still too tight and wrong shape for my feet.