Hi guys,
I am 5'7" and have always ridden medium bikes (Trek session Aluminum & carbon, Intense Socom & Morewood Izimu). I ended up ordering the small frame and I am very happy with it. It is definitely longer than my older bikes, but it is so easy to ride due to the short chainstays. I don't think I would be able to ride a medium frame on this bike as it would be too long IMO. I hope this helps.
I am 5'7" and have always ridden medium bikes (Trek session Aluminum & carbon, Intense Socom & Morewood Izimu). I ended up ordering the small frame and I am very happy with it. It is definitely longer than my older bikes, but it is so easy to ride due to the short chainstays. I don't think I would be able to ride a medium frame on this bike as it would be too long IMO. I hope this helps.