Schooling help, unbalanced

Does she go fast in canter? If so I would try to really collect her and slow her down before asking her to turn and only turn gradually to start with, until she gets more balanced.
 
A good qualified instructor should be able to help firstly. If she is old and stiff you may never change her. It could also be a back issue. Work on suppling exercises and leg yielding, try sitting to the inside of the circle and saddle, she will have to move out to balance herself. How does she feel in the rein, this can be a clue to underlying stiffness.
 
Ok, not much info but this is due to a lack of engagement of the hindleg on the inside. Hence the 'motorbiking'
A lot of work can be done in the trot using transitions and concentrating on the connection and straightness. This relates dirrectly to how the hindleg is placed under the body through to the hand. The horse then needs to learn how to remain in balance through all the questions of balance that we place on him, like in corners and in circles not by using his neck and your hand but by finding his hind leg.
He therefore needs to take time to finish each step and you need to develope aids that help him and co-ordinate his reactions; i.e inside leg at the girth tapping=his inside hind reacting, outside rein=containment of energy. You need to be sure that you can provide a still and consistent 'frame work' and that is where the hand is still relative to the horse and your body in balance upwards through your spine and downwards in relaxed legs.
You must not 'lean in' in the corners and your leg needs to be loose at the hip so that the lower leg is free to support and motivate whithout gripping upwards .As i have posted on a few occasions i use 'squares' to teach the feeling both in the horse and you the rider. this teaches you the rider what straightness is and how difficult it is to get via the inside leg pushing the inside ribs out to the outside supporting rein. At the corners you halt using your enclosing fingers and a stretch upwards in your spine and reaching down and around with your legs. you need to turn your shoulders with elbows at 90 degrees and above your hips, too many people turn their heads but not their shoulders and you need also to ensure that you have a clear inside leg at the girth and an outside leg behind the girth that supports and holds the hind leg on so that the inside hind needs to step forward. when you make a 'turn' like this you give your horse a clear frame work for his balance and your co-ordination. It really is important that you look up and see where straight ahead is as this will get you feeling the hindlegs and by this you will then start to understand through feel when and where the hindleg needs to be placed.
If you look at my other posts it describes this in greater detail and how to ride it in various paces and the benifit it has.
basically you will need help from a good instructor but in the meantime this exersice will help all horses all riders at all ages and stages of training
Good luck.
 
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