Instructions
Measure your horse's withers using a thin, flexible piece of wire 16 inches long. Bend the wire in the center and set it on your horse's back about two fingers behind his shoulder blade. Be sure the wire is molded to your horse's back; it should not spring back when you let go of it.
Measure the width between the two ends of the wire in centimeters if you are purchasing an English saddle or in inches if you are purchasing a western saddle; this is your horse's tree size.
Place the properly fitted saddle on the horse's back. The front of the saddle should sit over the horse's withers. Check that the seat area of the saddle is level. If it is tilted upward, slide the saddle back until the seat becomes level. If it is tilted downward, slide the saddle forward until the seat is level.
Attach the girth or cinch to the buckles on the right side of the saddle. Bring the girth under the horse's belly and attach it to the buckles on the left side. The girth should be tight enough to keep the saddle in place, but loose enough that you can fit several fingers under the girth.
How to Fit a Flex Tree Saddle on a Horse
A flex tree saddle features bars that are more flexible than those of a standard wooden tree, meaning the saddle can flex and conform to the horse's back. While the flexibility provided by a flex tree saddle can help the saddle fit the horse's back, it does not create the correct fit. You must fit the flex tree saddle to the horse just like a wooden tree saddle. It is important to measure your horse's back properly in order to ensure the correct saddle fit.