The forks are the device that holds the front wheel and are controlled (steered) by the stem and handle bars. Forks come in solid and suspended versions. The solid version is similar to a bicycle fork in design, an upside down u shape with slots at each end to attach the wheel. The suspension version will usually use coil spring over shock system in each side or an elastomer spring in each side. Fork suspension systems travel is usually shown in millimeters, 1 inch is equal to 25.4 mm.