this may help... http://www.youtube.com/watch?v=7Qvt29gv0X8
Size 1: Back length 34-40cm, Typical height 5ft - 5ft5inch
Size 2: Back length 38-43cm, Typical height 5ft3inch - 5ft8inch
Size 2: Back length 43-48cm, Typical height 5ft8inch - 5ft11inch
Size 4: Back length 48-54cm, Typical height 6ft...