j-lu has described her changing position between shoulder-in and halfpass. What she is not aware, is that as her position changes, so do her weight aids, i.e. how she is weighting the stirrups. Where the rider’s leg is on the horse’s side, i.e. at the girth or behind the girth, changes those weight aids as well. If the horse is very straight, which most are not, the rider might perceive the weighting of the stirrups as being equal. But, the rider must also ask themselves if the weight is on the rear edge of the stirrup correctly and the rider’s toes pointed up and not to ground.
The question when you ride, is which of the horse’s hind legs needs to take more energy of compression of the hock in order to do the movement. The answer is that the hind leg of the diagonal which needs to travel farther within the movement needs more energy. In shoulder-in, we need more energy taken over the outside diagonal. With half-pass, we need more energy taken over the inside diagonal. By virtue of where the rider’s inside leg is, hopefully at the girth if the horse is straight, that alone will be enough weight to help maintain the bend, and in shoulder-in, also direct the energy over the outside diagonal. We look the direction of travel, which also changes the weight aids. line. Our pelvis stays “bent” to the curve that would be a 10-meter circle segment. It is that bend of the rider’s pelvis that maintains the bend of the horse. But, the fashion in which we move the upper body, and how we change that weighting by moving only the position of our head.
For shoulder-in, the upper body is also bent to the 10-meter circle, while the head turns slightly outward in order to look the line of travel. This actually also changes the height of each of the rider’s shoulders, and changes the angle of deflection of the extra energy being created. For a diagonal pair to travel farther, that diagonal needs to elevate more. In other words, we need both more energy, and we need to send that energy on a higher trajectory so that it travels farther.
The same is true as to what we need to get the inside diagonal to move farther for the half-pass. So the rider’s weight aids need to change. The focus now becomes a need for greater weight in the horse’s outside hind leg. By virtue of the rider “looking the line of travel,” the trajectory of the energy angles higher.
The rider should not have to use spur or extra leg to get the horse to move directionally. Lots of luck on that one because…both horse and rider are generally crooked. That changes a lot. The biggest mistake that a rider can make in half-pass, is thinking you can use that outside leg in half-pass to “move” the horse laterally. Riders often take their leg back even more than it should be, trying to get the horse’s hindquarters over. This makes the balance even worse as it dumps weight onto the horse’s inside shoulder.
By the level of the half-pass, the rider should understand how to change her weight aids to effectively change the horse’s weight to the diagonals in order to straighten the horse. I have not seen much of this happening. As the results, the horse stays crooked and if that horse is hollow right which most are, the half-pass to the left is easy, and the half-pass right is a mess. If the horse has been trained to the weight aids from the beginning of the training, then half-pass is not much of a problem. If half-pass is a problem, then all sorts of other movements are going to be a mess as well…the walk pirouette, the canter pirouette, the flying change, and latter on, the canter zig zag, which has my vote as the most poorly performed movement in dressage.
So when you go to do the half-pass left, and assuming that you have a hollow right horse, just sit up straight, and the crookedness will actually help you. Do not try to push the horse from the outside. Let your leg contact the horse’s outside only by virtue of how the horse is moving. This is your leg breathing with the horse within the movement. You leg contacts only because of the way the horse is moving. If that is not happening, it means you are tensing muscle somewhere, and actually retarding the motion.
With that same hollow right horse, the crookedness will hurt you, the more crooked things get. The horse is not taking enough weight on its left hind, and is not elevating its right shoulder enough. Slide your left leg back just a hair…not much. You need to keep weight in your heel of that foot…not in the toe. Now raise your right hand a bit and take your left shoulder back. Whether you know it or not, your left shoulder is slouching. Do not quite look the line of motion in this half-pass right direction. Look more toward the horse’s left ear. Do not lose the weight from the rear edge of your stirrups. Do not allow your toes to point to ground. Think about lifting your toes on your left leg to help with the correct position. If your stirrups are too long, there will be a tendency to lose your right stirrup, and this will also be the case, if you do not have enough weight aid on the left stirrup.
Your legs must both fall against the horse’s sides in response as to how the horse is moving. For the half-pass right your right leg will fall too deeply if the horse is fairly crooked, and your seat will not effectively maintain the rhythm of the gait. The half-pass right will become labored, and sort of hoppy. Think of riding a barrel in water. The barrel begins to roll, and in the case of a hollow right horse, your barrel is rolling toward the right. If you do not straighten the barrel correctly, you are going swimming. You need to get weight on the left side of the barrel to keep it from rolling over to the right. You use your weight aids to keep that barrel steady in all movements. And by the way, when you lift a rein, you are keeping the horse’s shoulder from rotating farther inward, and asking the horse to move away from that rein.
