A release binding is shown for releasably attaching a ski boot to a telemark or cross-country ski having a load spool with a circumferential groove and a substantially elliptical holding portion attached perpendicular to the bottom of a toe plate. The substituents R1, R2, R3, R4 of general formula are defined as the description. The side frame includes right and left side plates and a connecting element for interconnecting the right and left side plates.