Abstract: A header for an agricultural vehicle includes: a header frame; a flexible cutter supported by the header frame and including a plurality of cutting edges; a support arm coupled to the flexible cutter and pivotable with respect to the header frame; and a sensor assembly including a pivot sensor directly coupled to the support arm and a linkage including a linkage arm coupled to the pivot sensor and the support arm such that pivoting of the support arm also causes pivoting of the linkage arm, the pivot sensor being configured to output a total pivot angle signal corresponding to a pivot angle of the support arm plus an additional pivot angle of the linkage arm when the support arm and the linkage arm pivot.