Differential Spoke-Tension Sensing for Estimating Bicycle Rear-Wheel Power

Abstract

This open technical disclosure proposes a low-cost method for estimating bicycle rear-wheel power from changes in the tension of ordinary wheel spokes. The proposed architecture uses two spoke-coupled sensing modules: one on the drive side and one on the non-drive side of a dished rear wheel. Each module measures strain, or another quantity correlated with spoke tension, together with wheel angular position. During a short torque-free coasting interval, the system records a side-specific, angle-synchronous baseline representing repeatable effects of radial loading, wheel geometry, imbalance, and rolling conditions. During subsequent riding, the baseline is subtracted from both measured signals. The residual signals are normalized and combined to estimate torque transmitted through the rear hub-to-rim spoke system. Rear-wheel power is then calculated from estimated torque and wheel angular velocity. The disclosure describes the mechanical basis, bilateral sensing architecture, phase alignment, calibration alternatives, weighted least-squares torque estimation, disturbance sources, implementation variants, and a proposed experimental-validation procedure. It explicitly considers dynamic weight transfer, road excitation, braking, temperature drift, sensor attachment, centrifugal loading, angular acceleration, and the limitations of sampling only one spoke on each side. The method is presented as a physically grounded but experimentally unvalidated engineering hypothesis. No prototype performance or measurement accuracy is claimed. The publication openly documents the concept, defines its falsifiable technical boundaries, and provides a basis for independent implementation and experimental evaluation.