has the largest online selection of Catalyst 4 parts available. frame, side guards, casters, forks and stems and more are available now for the Catalyst 4. We ship your Catalyst 4 parts directly from the manufacturer. Get the Catalyst 4 parts you need at the lowest prices possible. It’s ’s priority to provide you with top quality, OEM Catalyst 4 parts, straight from the manufacturer. If you are unable to find the Catalyst 4 part you were looking for, call customer service at 1-800-236-4215.