So a shoulder in is keeping the horses haunches on the rail and pushing their shoulder over ... almost creating three tracks... so *closes eyes and tries to visualize* I would use my inside leg to keep his haunches on the rail, but have pressure on my outside leg to keep the shoulder off the rail? Or maybe place my inside leg further back and keep the outside one by the girth? Where would my seatbones rest ... other then being in the saddle
Shoulder-in...hind feet continue to track straight on the original track (it does not have to be performed on the rail, it's just where you start to help control the haunches) and do not cross one another, inside fore leg crosses outside fore leg...shoulder-in can create 3 or 4 tracks depending on the degree of it. Shoulder-fore is the precursor to the shoulder-in and does not quite succeed in creating 3 clear tracks. Shoulder-fore requires the horse to bend through the body as if travelling on a 20m circle, shoulder-in requires the horse to bend through the body as if travelling on a 10m circle.
First of all, to do a shoulder-fore/shoulder-in your horse has to be on the aids, in front of the leg, accepting contact and everything that comes before those things; forward, rhythmic, relaxed, supple. The horse must also understand inside leg to outside rein, and you have to be able to control and move the shoulders at will etc...
When that is achievable all you have to do is move the horse's shoulders 'in' a couple inches. The outside leg moves slightly behind the girth to prevent the haunches from falling out, the inside leg goes at the girth and pushes the horse forward into the outside rein and the outside rein controls the whole shabang. There may be a touch more weight on the inside seatbone, but really for the most part the rider sits quite even, making subtle corrections as you go along.
The picture of the shoulder-in in this thread is not correct. It would score a 5 at best. The horse has evaded that outside rein and popped his shoulder and has way too much bend through the neck. The rider is using too much inside rein. The horse needs a very strong half halt and to be straightened....I'd actually have the rider, ride a short diagonal out of this position to straighten the horse. Also notice the rider and horses shoulders and hips are not lined up. The rider's hips should be facing forward in the direction of travel with the shoulders slightly turned in.
Less is often more and if you look at the horse doing haunches-in...you can see how much straighter the horse is...that's how the horse should look in shoulder-in, only with the body in the reverse position.
A haunches in would kind of be the opposite. The outside leg would slide back and you would create a minor counter bend. Your inside leg would stay steady, preventing your horse to leg yeild... right?
No, there is no counter bend in haunches in. The horse's front end stays straight and on the original track, then the rider moves the haunches to the inside track a couple of inches. The outside hind then crosses the inside hind. There is a soft bend through the horse body...the horse being bent in the direction of travel.
The outside leg does go behind the girth to move the haunches over. The inside leg is at the girth to keep the bend. Again, the outside rein controls the whole shabang.