Solving the standing-start paradox in track cycling.

Standing starts in track cycling appear paradoxical: a departure 'from rest' can exhibit a non-zero bike velocity at the official signal. We resolve this apparent contradiction by identifying a brief transitional regime, initiated around the gate-release window and preceding steady pedalling, in which coordinated whole-body motion provides the initial impulse. Using direct characterization of the starting gate, high-speed videography of elite specialist starters, anthropometric centre-of-mass (CoM) reconstruction and instrumented crank-torque measurements, we separate three concurrent contributions to the early motion: gate braking, inertial forcing from rapid CoM motion and pedalling propulsion. The resulting dynamical model reproduces the measured velocity-time profiles and explains lawful non-zero start velocities without prescribing them as initial conditions. Optimization analyses show that start performance is governed primarily by the timing of initiation relative to the release window and by the explosiveness of the CoM motion, whereas gearing and mass have only minor effects over this early interval. The model therefore provides practical guidance for improving the first instants of the track-cycling standing start within the rules.