Designing the gradient for a rainbow slide requires balancing safety, thrill, and site conditions. Typically, the main slope is kept between 13° and 30°. We recommend 18°–25° for straight sections and 15°–20° for S-curves to maintain a safe sliding speed of 2 to 6 m/s. A key design rule is that the slide length must be at least six times the vertical drop. If the natural terrain is too flat (below a 9% grade), we build up the slope to meet this ratio.

The design is also customized based on the target audience: slopes for kids are generally kept under 15°–20°, adult slides max out at 20°–25°, and high-thrill "scream" slides can go up to 35°–42°. Finally, for safety, the end of the slide must feature a buffer zone of at least 20 meters, equipped with a deceleration slope or cushioning pads to effectively absorb kinetic energy and protect riders.