Are you left handed?
My son is ambidextrous, with a slight preference for his right.
He tends to put more weight on his right side, so over time, rather than staying centered up in the saddle, he's actually pushing down with his right and thus, the saddle is simply rolling a little at a time until he has to shift his weight and pull the saddle back to center.
Can you get more pictures, or perhaps video? I keep looking at the picture and your saddle APPEARS centered up, just looking at the gullet - certainly not off enough to explain the wild difference between your two stirrups. I mean, just looking at it, the first thing I'm really thinking is you have one stirrup way, way too short and the other out about one hole too long. I can only assume that's not the case though and you're riding with even stirrups.
So, next question - what kind of pad is that under your saddle? A cheap pad can allow for saddle roll, no matter how tight you cinch your horse. We had a fleece backed Mustang Manufacturing pad when we first started out, my son bought it at Paul Taylor's in Pilot Point Texas... and I. hated. that. pad. Never could get up in the saddle without the saddle rolling on the mount, no matter how tight we cinched the horse up. Do you perhaps use a mounting block, and maybe aren't realizing the pad is causing the slip?
Ignore that bolded paragraph - This is a treeless saddle and I missed that.
Are you walking your horse around a little, rechecking the tightness of the cinch? Some horses can blow up like Mrs. Puff from Spongebob... I've seen my friend's older mare, Twinkie, puff up so much that after she's walked around a little bit, and the cinch is re-tightened, there was a 5... FIVE... loop through the D difference. Not holes in the latigo, I mean loops through the D and back out again. She's a master at blowing up and holding the puff.
"We are here to laugh at the odds and live our lives so well that death will tremble to take us."
Last edited by AtokaGhosthorse; 07-30-2019 at 01:38 PM.