I have to say your "description" of the flank strap and spurs is not an honest evaluation. Sounds like spin to me:) If not to keep an animal bucking what is their purpose? And you don't stay on by anchoring your spurs to the animal. You are suppose to run them up and down on thier shoulders, is what I thought. If they were used as an "anchor" then they would be a pain causer.
Once again, I don't believe they actually cause pain, but they do help to keep the animal bucking.
Becky
You are correct on the spurs as to bareback and saddle-bronc riding; but not for bull riding. Bareback and Saddle-bronc riders are required to spur; for bull riders its an option but not required for a score (just as bronc riders must "mark out" - bull riders don't have to worry about this). Also - bronc flank straps are pulled as the animal leaves the chute - bull riding is much different.
It is true that the flank strap makes the animal want to kick; but there is lots more to bull riding than just a bull that kicks because that wouldn't be that hard to ride. Bulls do more than that. They lunge, they spin, sometimes they will change directions in their spin, and things like that. I am willing to agree that the flank straps are an annoyance to bull; but not that they cause pain or torment. If the bulls were in pain, they would be less inclined to perform.
Also, you must remember with the spurs about the thickness of a bulls hid compared to that of a human being; a bulls hide skin is even thicker than a horses. I have never heard of an animals bones or internal organs being damaged as a result of spurring - I have never even see a bull bleed from spurring.