All of the componants work exactly like a bicycle. The two front wheels steer with handlebars attached to tie rods and the back wheel brakes with the peddles. The front wheels are 16 inch. One of the seat/peddle assemblies has a 16 inch wheel and the other has a 20 inch wheel. These assemblies can be changed out in 30 seconds or less and are double pinned for safety. This new product idea can accomodate a wide variety of ages from smaller children to adults and has been tested to hold up to at least a 175 pound rider. My grandchildren love it.