This study examined how the morphology and thermodynamic stability of α-synuclein amyloid fibrils govern their disaggregation by the human HSP70–DNAJB1–Apg2 chaperone system, relevant to Parkinson's disease. Across four fibril polymorphs — and fibrils amplified from patient brain extracts — chaperone disaggregation efficiency correlated negatively with fibril thermodynamic stability. Flow Induced Dispersion Analysis (FIDA), on a Fida 1 instrument, was used to quantify soluble α-synuclein monomer across a chemical (urea) depolymerization series, providing the monomer readout from which each fibril's thermodynamic stability (ΔG) was derived. It is an example of using FIDA to quantify a protein in solution to derive a thermodynamic measurement.