Flying Horse 2-Stroke/4-Stroke Motorized Bicycle Engine Pulley Wheel With Bearing &ndash; Gas Bike Chain Tensioner Idler Wheel Replacement The Pulley Wheel is an upgraded chain idler pulley wheel for smoother riding compared to the stock nylon pulley wheel that comes with most bicycle engine kits Installation is a breeze: unbolt and remove your stock idler pulley wheel, bolt this pulley wheel in to the stock bracket, adjust your pulley to your chains needs, and you're ready to ride