Understanding Saddle Fit
To get a proper saddle fit, first we need a centered and balanced rider. Being in balance refers to having the center of balance aligned over the base of support. From this position the rider can easily adjust to stay with the motion of the horse. To find the rider’s center of balance, we divide the body into three planes: lateral, medial, and transverse. The lateral plane is an imaginary line through the rider’s ear, shoulder, hip and ankle, or spur, when in the saddle. The medial plane is an imaginary line through the center of the face, navel, and between the feet. The transverse plane crosses the body just below the crest of the hip. The intersection of these three planes is the center of balance, and is slightly below and behind the belt buckle. On the horse, the same principles apply. The lateral plane is from the point of shoulder to the point of the hip. The medial line follows a vertical line through the spine, and the transverse plane is about 3 ½ to 4 inches behind the base of the withers, in alignment with the 14th thoracic vertebrae. Since horses are much larger and stronger than the rider, they can carry a rider in and out of balanced position, but out of balance is more tiring for the horse. You can get better performance from your horse, and definitely less fatigue, if you maintain a position of balance. Other factors in proper saddle fit start with size compatibility between the horse and rider. For example, a large man riding in a 17-inch seat saddle on a horse that is too small for him would be forced to sit behind the horse’s center of balance. Another factor is gender. A woman’s hip joint is behind the center of balance point of the pelvis and, thus, has a tendency to rock the hips forward. A man’s pelvis is forward, creating the tendency to rock backward or to sit more on their pockets. All these factors affect the balance relationship between the horse and rider. Just as important in rider balance is how the saddle is made. Many western saddles are made with the low point of the seat at the corner of the cantle, which is behind the balance of the pelvis. This puts the rider out of alignment, forceing the hips to roll backward and the rider’s center of balance to be behind the horse’s. Putting the hip in this position causes the rider’s knees and feet to turn outward, so that leg contact is improper, using the back of the leg rather than the inside of the thigh and calf. Sitting in this position also straightens the arch in lower back, causing fatigue. A saddle that places the low point of the seat in the proper place, remains full at the corners of the cantle, and is concave will allow the hip to roll slightly forward, bringing the rider into alignment with the horse by moving his center of balance forward. This also puts the legs into better position to maintain a natural curvature to the spine, giving the rider a sense of sitting in the saddle rather than on it. Distribution of the rider’s weight on the horse’s back. A saddle with a 15 ½ to 16-inch seat length has a bar length of about 23 inches. The center line of the bar should be 3 ½ to 4 inches behind the base of the withers and in alignment with the horse’s center of balance. Measuring from the center of the bar, the rider’s weight under the seat bone should be the same distance to the rear of the center as the center of the stirrup leather slot is ahead of the center line. So if the rider carries one third of his weight in the seat of the saddle, one third on the thigh, and one third in the stirrups, his weight will be equally distributed on the horse’s back along the full length of the bar. However, if the rider’s hip is allowed to rock back, it will put the majority of the rider’s weight on the rear third of the bar, unevenly distributed on the horse’s back. This puts undo stress on the first and second lumbar vertebrae, which is the weakest part of the horse’s back. Not having any skeletal support from the ribcage, the horse is forced to carry the rider’s weight more by muscle, which is more tiring for the horse and hinders him from arching his back, necessary for any athletic movement such as reining, stopping, or turning. Of course, there are exceptions to the rules. For example, a cutting horse needs to move off its hindquarters, keeping its forequarters free. So, most people who ride cutting horses will want their center of balance a little behind the horse’s center of balance. But most riders, from dressage to trail riders, will greatly benefit from maintaining proper body alignment and with equipment that helps them maintain proper body alignment. Relationship of the saddle tree to the horse’s back. The tree is the foundation of the saddle, and regardless of how pretty it looks, the saddle is no better than its foundation. With this in mind, your saddle maker should use the very best tree available. The fit of the tree needs to be compatible with the horse, not only when standing, but most importantly, when in motion. The tree can appear to fit while the horse is standing still, but may not fit as well when the horse moves, due to the motion of the horse’s back muscles. The motion varies as he changes gaits, travels over varying terrain, or performs various athletic moves.
There are five parts to the saddle tree: the horn, the swells, the cantle, and two bars.
The function of the bars is to distribute pressure evenly over the entire surface so that the horse can comfortably carry the weight of the rider without creating spot pressure that can cause pain and physical damage.
The large surface under the swells and the rear of the bar under the cantle are referred to as the pads. The area right behind the stirrup leather slot is called the waist.
If you look notice the difference of the angles of the bars between the front and the rear of the saddle, this is known as the twist. Looking at the bar from the edge, front to back, this is called the rock, as in a rocking chair. The bar in cross section has a round profile on the bottom and this is called the crown.
The skeletal structure of the horse. The horse has eighteen ribs, thus eighteen thoracic vertebrae. This starts at the break of the withers and continues to the first lumbar vertebrae. The vertical processes of vertebrae T1 through T10 form the withers. These vertebrae tend to slope toward the rear. The height of these vertebrae increases from T1 thru T4, with T5 and T6 forming the crest of the withers. T7 thru T10 decrease progressively in height toward the base of the withers. As the vertebrae continue toward the center of the back, they become more vertical until T14, where the process is vertical. As they continue past T14, they tend to tip slightly forward to T18, where the thoracic vertebrae end and the lumbar vertebrae begin; this is the weakest point of the horse’s back. With the skeleton forming the structural framework of the horse’s body, the muscles provide the motion. Muscles only contract to pull the bones that they are attached to. The major muscle groups in the back that pertain to the fit of the saddle tree are the spinalis, longissimus dorsi, posterior trapezius, the latisimus dorsi, and the gluteus. These muscles attach to the shoulder blade, or scapula, the spine, and continue to the hip and across the loin area. A horse moves by the contraction of certain muscles, which when working in unison, move the bones of the skeleton to pull the body over the foot. As this happens, the shoulder blade swivels with the motion of the foreleg. The pivot point is below the top of the scapula. As the foreleg moves forward, the top of the scapula, which is cartilage, moves backwards. As the appropriate muscles contract pulling the horse’s body forward over his foot, they tend to bulge behind the withers in the front of the saddle tree bar. At the same time, the opposite hind leg moves forward in a diagonal stride. This causes the saddle bar to rise slightly in the rear, as the opposite toe of the bar comes in contact with the bulging muscle behind the withers. A bar that is too straight or doesn’t have enough flare, or has inadequate rock, will put pressure on this muscle. Most horses respond to this pressure by shortening their stride, not walking out well, or in the case of a gaited horse, refusing to gait. Prolonged use of an ill-fitting saddle can cause bruising, dry spots, white hair, and saddle sores. If the tree is not compatible with the horse, and rocks or bridges, or if the bars are too long for the confirmation of the horse, problems will occur. A rider sitting out of balance, or sitting behind the vertical, can load the back of the bar, causing the center of weight to be shifted back, forcing the horse to carry this weight on the lumbar spine where the support is muscular and not skeletal. This causes the back muscles to tire. When this happens it creates pain for the horse, his back will hollow, and his head will rise. Sometimes a rider, not realizing the cause of problem, will tie the horse’s head down, thereby creating more discomfort for the horse. A tree can fit the horse properly, but the horse can still suffer from a sore back caused by an out-of-balance rider.
Remember that as a horse’s foreleg moves forward, the top of the scapula moves backward and the muscle bulges, putting pressure against the toe of the bar. This motion is exaggerated in gaited horses that have more shoulder action. To accommodate for this, the flair to the front of the bar needs to start at the back of the front pad and increase toward the toe. It should not just flair at the front edge. This provides a flat surface against the shoulder, reducing the edge pressure. Placing a tree on the horse’s back, the 14th vertebrae should be slightly behind the rear stirrup leather groove and in alignment or close to the center of the length of the bar. Theoretically, the distance from the center of the bar to the center of the stirrup leather slot should be equal to the distance behind this center measurement to a point directly under the rider’s pelvis where the butt bones are located. This is good in theory and will be close in trees with a 15 to 16 ½ inch seat, but may not be the case with long or short seated saddles, or with horses that are not the right size for the saddle tree. The ground seat should be made in such a way as to support the rider’s hip and center him over this balance point. Seats that form a pocket at the cantle will force the rider’s pelvis to rotate backward into this low point and away from the center of the bar. This puts the majority of the rider’s weight on the back third of the bar and places most of the stress near the lumbar spine of the horse. This result is the muscles tire, the back drops, and creates a sore back. In this situation, collection becomes almost impossible. In addition the rider also loses the natural curve to his spine and will experience a sore back. Another common problem is positioning the saddle too far forward on top of, rather behind, the withers. This props the saddle up, tipping it to the rear and causing pressure at the tail of the bar, as well as loading and pinching the withers. As stated earlier, the tree can be a good fit for the horse and he can still develop a sore back if the rider is not balanced in proper position. Being aware that the balance point for most horses is in alignment with the 14th vertebrae; this ideally should align with the center of the saddle bar, and the rider should be balanced in relation to this point. It’s the job of a good saddle maker to form the ground seat in the saddle to position the rider over this point.