Years before, Ron had set himself the task of building a 90-hp Vincent, but every time his highly modified engine reached 7,500 rpm, the crank wheels had shifted on the crankpin, which is pressed in place with many tons of force. He’d thought about that, constructing in his mind a picture of the various flexing parts. And he had decided that the flywheel shift occurred when the “elephant ears flapping” mode of the flywheels, flexing toward and away from each other, came into step with the firing frequency. At that point, the flapping motion would greatly increase, possibly enough to move those heavy press fits. In this motion, the crankpin itself was acting as the spring, and that flexure continued right into the press fits holding the pin in the wheels. That motion, combined with torque pulses from the cylinders firing, had shifted the crank.