Balance with inertia adjustment with no inserts

A timepiece balance, with inertia adjustment for adjusting the inertia and/or poising and/or oscillation frequency thereof, including a hub arranged for cooperating with an arbour pivoting about a balance staff perpendicular to a balance plane, and a continuous or discontinuous peripheral felloe, connected to said hub by at least one joining surface, wherein said balance has no inserts, and that said felloe is made in a single piece with said joining surface and said hub in a micro-machinable material, or silicon, or quartz, or a compound thereof, or an alloy derived from MEMS technology, or an alloy obtained by the “LIGA” method, and wherein said felloe includes at least a first resilient arm including coupling means arranged for cooperating directly, in various coupling positions, with complementary coupling means comprised in said felloe to form, in a coupling position, a closed loop, the inertia of which relative to said balance staff is variable according to said coupling positions, and wherein said balance is in a single piece with said coupling means and said complementary coupling means.