About this item ? Aluminum Frame – The mountain bike equiped with Aluminum Frame. Lighter but stronger frame. ? 21 Speed Drivetrain – TZ500 drivetrain allows buyer to switch gears with smoothness. The positioning is accurate, and silky gear shifts without stalling. ? GREAT TIRE PERFORMANCE Ultra durable, the mountain bike tire made of high-quality rubber material and has strong puncture resistance and abrasion resistance, bicycle tire is suitable for riding in the mountain, jungle or on the city street. ? POWERFUL DUAL DISC BRAKE Our mountain bikes have precision mechanical disc brakes for more precise and controlled braking. Mechanical disc brakes are more effective than V brakes. ? QUICK INSTALLATION IN 20 MINUTES The Elecony bike arrives 85% assembled and includes free pedals and assembly tools. It is easy enough to put together in 20 minutes. The bike can be fully assembled with ease with the help of tutorial videos, and we are more than happy to help with any problems you may have during the assembly process ? Worry-free Returns and Exchanges – We offer 30 days no reason to return. Customers will be provided with high-level warranty and 24-hour customer service when contacting Elecony for any queries. service is 100% satisfaction guaranteed. About install: 1.86% of the bicycle has been assembled. You need to install pedals,front wheels,handlebars and inflate the tires.