An excerpt from my book Pianos Inside Out illustrates that the hammer slows down (the distance it travels every two millimeters of key travel becomes shorter) as the key reaches the let off point. By my observations from this series of photos, also confirmed by my measurements, in this action the leverage ratio changes from approx. 6.0:1 at key rest to somewhere between 5.3:1 or 5.2:1 right before let off.#actionleverage #hammertravel #actionratio #leverageratio #keytravel