Ahh, yes. With what bgpcf has added I now see, both sides of his collar are also ratcheted so he can't pull back and his thighs are going to be straining more as they can't relax even slightly to be behind the verical - nearer his feet. I tried to make myself get into a simialr position as you suggested, simply to see wher the most strain might reveal itself,  but of course without the suspension you can't keep any position similar to his, gravity and all that.:)

You asked about my experience. I was standing legs in a spreader, gag, blindfold. He put my wrists in leather restraints joined together behind my back. I had a reasonably thick leather collar. He got a rod, just like yours in the pics, tied one end to the wrist restraints and the other to the back of the collar. On the wrist end third of the rod was a hook. He tied a rope to the rod hook which he connected to a ceiling hook complete with ratchet and then down so he could pull it, thus raising the bar and my arms but not allowing me to bend forward to any extent that would relieve the strain. As the hook was not in the centre of the rod it raised at an angle, lower at the neck end. He tightened it, waited then again, click click as you are so fond of. Arms were busting for relief. I had to stay like that for a time, took some doing actually and built up quite a sweat. My "get out" was to choose, get out sooner - more strokes of the flogger, the more I could stay put the fewer the lashes. It was a good session.