The motor controller measures whether the rider continues to pedal at the same speed or whether it's accelerating. The motor support then adapts to this, increasing the motor support when the rider accelerates or remaining at the nominal motor support when the rider keeps riding steadily at a constant speed. The Dynamic Support results in a natural riding experience which works best in assistance levels 1-3 on flat roads. But if you live in a more hilly area, or experience head winds on a regular basis, then assistance 4 along with the Boost button will help get you where you need to go.