|Imagine walking down (or up) a conventional stair. Each foot normally uses only about half of each tread, stepping out and over the unused section (shaded red).
||On a steeper stair or ladder, the unused half tread becomes an obstacle, significantly reducing the usable tread depth of the tread directly below. As the angle increases, the problem becomes worse.
||In contrast, the Lapeyre stair removes the unused half of each tread, allowing the foot to reach the next tread in a straight, direct line, providing more usable tread depth.