[QUOTE=beau159;7867920]
I don’t want this to turn into a Tom Thumb debate, but I stole these pictures from another forum because I think they are worth posting.
http://i84.photobucket.com/albums/k27/r_beau/TomThumbisbadpic2.png
http://i84.photobucket.com/albums/k27/r_beau/TomThumbisbadpic1.png
Just because a bit has a single joint mouthpiece like a Tom Thumb, does not mean the bit acts like a Tom Thumb. Subtleties are important.[/QUOTE]
No subtleties there, but pure mechanics.
Hold any bit in one hand, holding the bridle with the other above it and have someone handle the reins behind your back.
You will see that, with a mouthpiece made of two or several rather long pieces of metal, attached to anything with any kind of leverage, there is no two times, when they pull on one shank or both, you get the same response from those mouth pieces.
Horses are wonderful at reading so much more we use to indicate what we want and learn to ignore those kinds of bits for the finer points of communication.
Want to go left and use one of those bits, that no telling what that pull of your hand in the reins may do to it and the horse learns to understand that bit as saying, “my rider wants something, what else is telling me what that is, their weight, their legs, where they are looking?”, because the bit is anyone’s guess how it will poke around in their mouth.
Just as confusing as you can feel it in your hand.
A bit with direct action, where your pull is on the mouthpiece, no leverage, makes that communication much more clear too the horse.
That is why most people traditionally trained with a bosal or snaffle, didn’t go to a leverage bit, with a straight mouthpiece, until the horse was well trained and would not require but signaling to understand what it needed to do.
Don’t believe me?
Try it on your own hand, the bit in there like it would lay in a horse’s mouth.
Now, there are specialty bits that are made just for one kind of contact and those, like correction, chain and other type bits with other kinds of mouthpieces than a few long, connected pieces and that is not even talking about bits that transfer some of their action to nose or poll, like gags and other combinations.
Try doing that with a curb with any kind of large port also and see what you think, taking into consideration how a horse’s mouth is built, how that makes you hold your wrist, the equivalent of the horse’s larger palate, how it makes a horse hold it’s head.
Way before there were so many bits, we were already taught to always look at any bit carefully, check it out in our own hand and listen to it, see how thick or thin it may be to a horse’s mouth, how it balances, how it twists and turns when affected by reins, etc.
The real answer to any bit is, after you try it on your hand, try it on the horse you intent to use it and see how the horse responds, now that you have a better idea of the mechanics of it.
Some times, it would surprise us what some horses just like best.