Abstract: A flexible form for making street and sidewalk curbs uses C-channels such as is utilized in straight portions of street curbs, said C-channels carrying "V" openings spaced regularly evey 6 inches or so, to facilitate gradual bending, such opening being equipped with a U shaped spring which resists the bending and, at the same time, causes a uniform tension along the length of the curve. The V openings are located both in the straight interior part of the curve and in the slanted external part of the curve. The external part of the curve has other V slots vertically placed in the web and spaced one every 5 feet for a curve radius of 12 feet, such V slots correcting the vertical camber of an inclined bent form. The flexible form, once spring balanced, allows the casting of concrete in a continuous fashion.