21-SPEED - Compared with 7-Speed, 21-Speed can improve speed better. Outroad mountain bike can improve the Speed faster, change the Speed accurately and save more effort for uphill riding. SHOCK ABSORPTION DESIGN - OUTROAD all-terrain MTB uses shock-absorbing front fork, and the thickened outer wall is more shock-resistant. Thickened shock absorber helps to absorb shocks, which can greatly improve ride comfort. STURDY FRAME - This all-terrain mountain bike uses a high-carbon steel frame that combines quality and performance to resist deformation and stretching. The ergonomic design greatly improves the comfort during riding. 4 INCH FAT TIRE - Width up to 4 inches, 5 times more wear resistance than ordinary bicycle tires. Strong grip and anti-skid, fully able to challenge any terrain, conquer any off-road trails and urban roads. INSTALLATION VIDEO - The installation package includes all the tools you need to build and maintain your own bicycle. You can install it according to the installation video we provide. All this takes about 20-40 minutes. Fat tire mountain bike Brake system: Dual Disc Brake Shifter: 21-Speed Tire width: 4 inches Frame material: High carbon steel Size: 26 inches