Leblett 26 Inch Folding Mountain Bike, 21-Speed Thickened High Carbon Steel Foldable Bicycle,Good Damping Effect,Dual Disc Brake,Weight-Bearing 264.55lbs for Adults/Men/WomenDetails Variable Speed Positioning Chain: It uses a variable speed positioning chain, which is not easy to drop the chain during the ride and can make the gear shift more sensi..