A piano key mechanism for a pianoforte with improved dynamic performance has weights placed within each keystick in the region between the pivot point of each key and a point midway between the pivot point and the ivory end of the keystick. The arrangement of weights reduces the overall inertia of the keysticks thus improving the dynamic performance of the musical instrument and results in an average of the downweight and upweight which is heavier than the conventionally accepted value for that key on a keyboard.