I'm 5' 6 1/2" exactly. I looked at sizing information on some new Nishikis and their small frame says "riders up to 5' 7" and their Medium says "riders up to 5' 7" to 5' 11" At 5' 6 1/2 I fall towards the small frame or the one I should be on, but I ride a medium and feel fine on it. I'm not stretched, but my arms are straight out, but not elbow locked. I realize I should be on the smaller frame if I do some heavy trail riding, for sake of weight and control, but I control my medium frame just fine in the woods and it is comfortable on the road and not cramped. I've actually sat on the small frame way back when I bought my bike, but I bought the medium bike simply because I liked the color better(same bike) but between the small frame and medium frame, they felt the same to me. Anyone else fall between sizes? Did you feel you could go either way/ SMALL OR LARGE.