Shimano shoes: what is the correct equivalence of US and EU sizes? Or, which to trust more?
EU sizing is generally more inconsistent than US and UK sizes. For example, my shoes are all labeled 10 or 10.5US, but the EU size labels vary between 42 to 45. The size 45s are Shimano SPD shoes so yes, for the same EU size Shimano shoes are the smallest.
It is interesting that centimeter sizes are almost as inconsistent as EU sizes, even though it should be easy to take exact measurement of the shoe. Some brands are also inconsistent between models, so when shopping online it's worth it to read reviews and comments. Finally, to get an idea how the shoe could fit, find a photo taken from the top and compare the shape against shoes you have. The outline of the sole does not tell how the foot fits inside.