Brace height is the distance from the pivot point of the bow’s riser located at the deepest part of the grip on the belly side of the bow (the side facing the archer) to the bow string when the bow is undrawn.
Most traditional and compound bows have brace heights between 6 inches and 8 inches.
In addition, it is important to note that when an archer chooses a given anchor point (the place to which the archer draws the arrow’s nock on each shot), their draw length effectively becomes fixed and bows with shorter brace heights cause the arrow’s nock to travel over a greater distance than bows with longer brace heights do because the distance from the archer’s anchor point to the brace height position is increased over that of bows with longer brace heights.
Consequently, bows with shorter brace heights produce higher arrow speeds than bows with longer brace heights.
But, you should also be aware that bows with shorter brace heights are less forgiving to shoot than bows with longer brace heights and an archer’s form must be near perfect to achieve pin point accuracy with a short brace height bow.
It should be noted that brace height can be easily changed by removing one end of the bow string from either the limb tip or the cam and then twisting it as many as thirty or forty rotations to shorten the string.
That way, when you reattach the bow string, the shorter bow string length will cause the bow’s limbs to bend more and increase the brace height.
However, this is an action that you only need to take when tuning a traditional recurve or long bow since, when doing so, even a slight change in sting length can cause a significant reduction or increase in both noise and vibration.
The reason that brace height is important when selecting a compound bow is that compound bows with shorter brace heights are faster but less forgiving to shoot than compound bows with longer brace heights are.
Also, the reason that brace height is important to the traditional archer is because increasing or decreasing the bow’s brace height can cause a traditional bow to become significantly more or less smooth and quiet to shoot.
Knowing how to measure the brace height of any bow is important so that an archer can either choose the best compound bow for their intended purpose or tune their traditional bow for increased accuracy.