Join Date: Jun 2009
Location: Ontario, Canada
• Horses: 0
Roll more forward onto your thigh when you post, that helps keep your leg still.
Additionally, little bits of paper placed under your thigh and calf. The top inside of your calf, right below your knee is where the most amount of contact is supposed to be, at least for H/J. For dressage, it's more distributed equally.
Schooling no stirrups is good, but unless you're practicing perfectly you're going to be picking up bad habits. Another thing you could try (on a safe horse, with supervision) is tying your stirrups to the girth with binder twine. Binder twine will break in the event of an 'oh crap' situation, so it's safe, and it really helps you keep your leg still.
If you feel nervous about regular binder twine, you can try dental floss, or simply fraying the binder twine so it has like 2 strands attaching it.