Instructions
Locate the stirrup bar. It is underneath the jockey (small flap next to the seat on either side of the saddle). Pull the buckle of the stirrup leather down away from the stirrup bar. Notice that the stirrup leather has multiple, evenly spaced buckle holes in it. These holes are used to set the correct stirrup length. You move the buckle up and down the holes in the stirrup leather to adjust stirrup length.
Place your fingertips on the stirrup bar and step an arm's length away from the saddle, extending your arm fully without losing contact with the saddle. Place the bottom of the stirrup under your armpit. The metal base of the stirrup should touch your armpit with the stirrup leather pulled taut between you and the saddle. Adjust stirrup leathers as needed until stirrup leather is approximately the length of your arm. Adjust both stirrup leathers.
Mount the horse. Sit comfortably in your normal riding position, holding your legs in the correct position. Attempt to slide your foot into the stirrup. If your foot slides in while in the correct riding position and feels comfortable and stable, your stirrup is the right length. If not, allow your leg to dangle and see where the stirrup hits your leg. A stirrup that is the correct length will have the bottom bar of the stirrup hitting just below the ankle. Adjust stirrup as necessary. Make sure both stirrups are the same length.
How to Find and Set an English Saddle Stirrup Length
Stirrups are an important part of your English saddle. Stirrups are used for several purposes: to assist riders when mounting, to help riders maintain proper leg position and to increase rider stability in the saddle. Stirrups are effective only if they are the correct length for the rider's leg. A stirrup that is adjusted too short will cramp the rider's leg, make them more inclined to pop out of the saddle and negatively affect their riding position. A stirrup that is too long is virtually the same as having no stirrup at all.