I'm 6'1 180lb and got the large.
The length for the arm is good but it felt really big around the abdomen/chest area. Like the other reviewer said, it feels drafty.
I think medium would be a better fit but unfortunately I'm overseas and can't return it
I normally wear US12 in most shoes. My left foot is slightly longer than my right by like 5mm or so.
I ordered the US11.5 because everyone said they run big, but I find it is probably ever so slightly too small in the left foot.
If I was to order again I would get the size 12
But these shoes are great, I love the blue colour and they are super super sticky on my pedals for my mountain bike.