Remember, as the rating goes up, so does price. Frames Frames, which are also called chassis, come in plastic, nylon, aluminum, titanium and composite materials. Metal frames are usually stiffer and used in more high-end hockey skates. Racing skates tend to go more exotic with titanium and composite materials, even though there are some very good plastic frames on hockey and racing skates. Recreational and fitness skaters will usually find plastic and nylon frames on their models.
Flat frames are non-adjustable and made so that all the wheels touch the ground at the same time.
Flat frames are more stable and a little faster. In the rockered position, the two middle wheels touch the ground while the end ones are off the ground slightly. This results in a smaller turning radius, which makes the skate more maneuverable, yet less stable. Number of wheels per frame also varies with intended use. Many kids and women's frames sport only three wheels because of the shorter frame length.