, here is another complicating factor that occured to me while cleaning the corral:
English riding. The US Cavalry manual calls the first "rein effect" an Opening or Leading rein. The inside hand is brought FORWARD and inside the turn. I use this direct rein all the time.
The second one is called "The Direct Rein of Opposition". It is described as "The right [inside hand for the purpose of the manual)...is carried slightly to the right, and drawn to the rear, to a point where it becomes effective. The neck, perforce, bends to the right as a result...The sharpness of the turn is regulated by the amount of tension on the [inside] rein.
When I took western lessons, the "The Direct Rein of Opposition" was used for one thing: A One Rein Stop. Heaven help a rider who ever pulled back on one rein for anything other than an ORS. I was chewed out more than once since I had read George Morris's book before taking lessons. Since then, my direct reining consists of an opening rein. Period. I don't like the ORS, but I never cue a turn by bringing the inside rein directly back. I also don't know how other western riders have been trained.
Could this result in what an English rider might see versus what a western rider might see? Could that change how a Tom Thumb bit moves or folds in the mouth?
Originally Posted by Idrivetrotters View Post
...A curb bit has shanks which put pressure on the poll and ads a lot more pressure to what the mouthpiece can do. Larger the shanks the greater the pressure.
Now that I got that out of the way Tom Thumbs in the Western world are garbage. Those straight shanks put an incredible amount of pressure on the horse's mouth, poll, and jaw. Shanks that are swept back have much less leverage and can be used for direct reining.
Larger shanks do NOT cause more pressure. The ratio used in the shanks control the mechanical advantage. You can design an 8" shank that has a mechanical advantage of 2:1, and a 4" shank that has a mechanical advantage of 4:1.
Straight shanks do not apply more pressure than bent shanks, provided the distance between mouthpiece and tip remain the same in comparison to the length of the top of the shank. If you bend a 4" shank, the bending will shorten that distance a little compared to a 4" straight shank, reducing the mechanical advantage. But one can design a straight shank bit with a 2:1 advantage, and a bent shank bit with a 4:1.
Straight shanks are designed for a horse who carries his head in the vertical. Then the BALANCE of the straight shank allows for 45-60 degrees of free rotation before the curb strap tightens. If you use a straight shank with a horse who carries her head at 45 degrees, the weight of slack reins will rotate the bit 45 degrees. This will not cause more pressure, but it robs the horse of the 45 degrees of "signal". It is a bad idea to use straight shanks on a horse who carries his head at 45 degrees, and a bad idea to use bent shanks on a horse who is expected to carry his head in the vertical.
"The amount of weight behind the shankís vertical line, and the angle of the mouthpiece, will determine your bitís balance. Comparing the bitís balance to the natural carriage angle of your horseís head could determine if you two are on speaking terms at the end of a long day.