Abstract: In cloth simulation particle systems models, bending stiffness involve forces which are either represented as additional springs, or as out-of-plane forces along surface normals. While the former solution is quite inaccurate for both small and large curvatures, the latter requires significant computation and is unsuited for fast computation required by real-time or interactive systems. We present a linear approach which combines simplicity and accuracy, being perfectly suited for the implicit integration schemes used in particle systems.