Even if much of the stress was relieved by the handle, fiber optics still don't like to be bent. Many shaving operations are not on a flat surface because the body's surface is not uniformly flat. It has positive (Riemannian) curvature on the chin, the jaw, the legs, and the mons; and negative (Lobachevskyan) curvature on the lip margins, the armpit, and the neck.