New 2018 Diamondback Mini Viper 16" Complete Youth Bike General sizing: XS=5'-5'3", S=5'3"-5'6", M=5'6"-5'9", L=5'9"-6', XL=6'-6'4". If you have questions about sizing, feel free to contact us for more information. Complete bikes will be partially disassembled and sealed in a factory box for shipping. Bikes arrive approximately 85% assembled and will require installation of parts and adjustment of components. If you are not comfortable with bicycle assembly or adjustments, we recommend bringing the the bike to a capable bike shop to be built.