Have a horse here that I can throw anything on (ie. tarps, bags, saddle pads, bags filled with rocks for weight etc). Yet when it comes to the saddle as soon as it lands on his back (wether I do it slow or quick) he takes off bucking. He’s good to cinch up with my surcingle and such. I can throw stuff all around him. It’s only the saddle. 

How do I stop this?

As soon as it’s fully on his back he’s gone and it falls off. I try to turn him so I can keep it on him but he kicks out at my knees. 

I’ve thought to try and tie him but worry I’ll get in a huge wreck.