Join Date: Dec 2010
Location: southern Arizona
You're sitting in the saddle wrong. Unless your feet are forward of your belt buckle, and you post 'forcibly' to put your center of gravity over your feet, you cannot hit the pommel.
Are you using a close contact jump saddle? Mine has the stirrup bars farther forward than my AP saddle, putting my feet a bit forward and thus forcing my hips farther forward - if I'm trying to get my center of gravity over my feet.
There are a couple of things you can try. If your feet are forward enough that getting your hips above them causes you to hit the pommel, you can:
1 - Find a different saddle. Gravity tries to force you so that your rump is in the lowest part of the saddle with the stirrup straps hanging straight down. Find one where this happens without putting your feet too far forward.
2 - Post differently. Regardless of saddle type, I prefer to post as minimally as possible. The goal is weight suspended off the horses back - and the horse cannot tell the difference between 1/4" and 6". I shoot for 1/4". I wear jeans, and my goal in posting is for my jeans to remain in contact while my body does not. And no, I don't meet that goal very often. Still, I try to keep both upward and forward motion under an inch.
I don't jump, and I don't know what jumping requires, so it could be different.
One last thing you might try: a jock strap.
One other thing: try posting without stirrups. When sitting the trot, most of my 'bounce-resistance' comes from the weight of my legs pulling my hips down (thus heels under hips), and from the friction of my thighs against the saddle. I don't know if it is different when jumping, but for flats, you shouldn't need your stirrups to post. It sounds like you are trying to balance above your stirrups with your weight in the stirrups, not your legs.
I'm a beginning rider who now mostly rides western/Aussie saddles, so YMMV.