This bike has a high quality ultralight aluminum frame and an inner wire designThe brake system consists of double Hydraulic disc-Brake. And 27-speed Shifters ensures total control in every situation.The 27.5-inch wheels and Lock out suspension fork make for a great ride experience on mountain roads, highways, and forestways.85% pre-assembled,easy to assemble,free pedals,required assembly tools included.The 16-inch frame is suitable for a person 5'2"- 5'8" tall.The 18-inch frame is suitable for a person 5'7"- 6' tall. The 19.5-inch frame is suitable for a person 6