On the reviews of Rider lovers, I bought these shoes, first in size 6, then returned them for 5s.  The difference in the sizes is ridiculous -- I usually wear 6.5, but since even the Rider site says to size down, I went with the 6.  WAY too big.  The 5s are unbelievably small!!! It feels like there are 3 sizes spanned between a 5 and a 6.
Also, the shape of the shoe where it lies across the top of your foot is very uncomfortable, in both the large/small cases, so I know that it was not due to incorrect size.  The outside edge comes up too high on your foot, while the inside edge lies right on your bone -- a blister waiting to happen.  Not happy that I have to lose $10 to return both pairs, either.