Post by rideanotherday on Mar 28, 2017 11:59:33 GMT
Rather than continue in on a different posting, I thought it would be worthwhile to discuss more about the action of curb bits.
This picture shows the parts of the bit so that everyone can be sure to be talking about the same thing. Physics is important to the use of bits. The relation of the upper shank (purchase)—the shank length from the mouthpiece to the cheekpiece rings—and the lower shank or lever arm—the shank length from the mouthpiece to the lowest rein ring, is important in the severity of the bit. The standard curb bit has a 1½" cheek and a 4½" lower shank, thus producing a 1:3 ratio of cheek to lower shank, a 1:4 ratio of cheek to full shank, thus producing 3 lbs of pressure on the chin groove and 4 lbs of pressure on the horse's mouth for every 1 lb placed on the reins (3 and 4 newtons respectively for every newton).
Regardless of the ratio, the longer the shank, the less force is needed on the reins to provide a given amount of pressure on the mouth. So, if one were to apply 1 lb of pressure on the horse's mouth, a 2" shank would need more rein pressure than an 8" shank to provide the same effect.
A long lower shank in relation to the upper shank (or purchase) increases the leverage, and thus the pressure, on the curb groove and the bars of the mouth. A long upper shank in relation to the lower shank increases the pressure on the poll, but does not apply as much pressure on the bars of the mouth.
However, longer-shanked bits must rotate back further before applying pressure on the horse's mouth than shorter-shanked bits. Therefore, the horse has more warning (pre-signal)in a long-shanked bit, allowing it to respond before any significant pressure is applied to its mouth, than it would in a shorter-shanked bit. In this way, a longer shank can allow better communication between horse and rider, without increasing severity. This is also directly dependent on the tightness of the curb chain.
When the reins are pulled, the shanks are pulled back and the purchase moves towards the horse's nostrils and the chinstrap squeezes up against the chin of the horse (acting as a brake). The degree of action of any part of the bit has to do with it's relative size.
The anatomy of each horse has a significant amount of variation. The port (center raised area) may or may not reach the roof of the mouth of every horse if the port is low as is common with a kimberwick or english style curb bit. The mouthpiece does rotate within the mouth (the purchase reflects the angle of the port and will indicate which way the port is pointing within the mouth), and with higher ported bits, it will impact and engage the roof of the mouth.
The curb bit's mouthpiece controls the pressure on the tongue, roof of the mouth, and bars. A mullen mouth places even pressure on the bars and tongue. A port places more pressure on the bars, but provides room for the tongue. A high port may act on the roof of the mouth as it touches. Some western style curbs, particularly the Spade Bit, have both a straight bar mouthpiece and a high welded port., thus acting on the bars, tongue and palate. In the wrong hands, such bits can be extremely severe, but on an exquisitely trained animal, they allow the rider to communicate with the horse with a simple touch of the fingertips to the reins.
(some information found: Price, Steven D., ed. (1998). The Whole Horse Catalog: Revised and Updated. New York: Fireside. ISBN 0-684-83995-4. Research rocks.)
This picture shows the parts of the bit so that everyone can be sure to be talking about the same thing. Physics is important to the use of bits. The relation of the upper shank (purchase)—the shank length from the mouthpiece to the cheekpiece rings—and the lower shank or lever arm—the shank length from the mouthpiece to the lowest rein ring, is important in the severity of the bit. The standard curb bit has a 1½" cheek and a 4½" lower shank, thus producing a 1:3 ratio of cheek to lower shank, a 1:4 ratio of cheek to full shank, thus producing 3 lbs of pressure on the chin groove and 4 lbs of pressure on the horse's mouth for every 1 lb placed on the reins (3 and 4 newtons respectively for every newton).
Regardless of the ratio, the longer the shank, the less force is needed on the reins to provide a given amount of pressure on the mouth. So, if one were to apply 1 lb of pressure on the horse's mouth, a 2" shank would need more rein pressure than an 8" shank to provide the same effect.
A long lower shank in relation to the upper shank (or purchase) increases the leverage, and thus the pressure, on the curb groove and the bars of the mouth. A long upper shank in relation to the lower shank increases the pressure on the poll, but does not apply as much pressure on the bars of the mouth.
However, longer-shanked bits must rotate back further before applying pressure on the horse's mouth than shorter-shanked bits. Therefore, the horse has more warning (pre-signal)in a long-shanked bit, allowing it to respond before any significant pressure is applied to its mouth, than it would in a shorter-shanked bit. In this way, a longer shank can allow better communication between horse and rider, without increasing severity. This is also directly dependent on the tightness of the curb chain.
When the reins are pulled, the shanks are pulled back and the purchase moves towards the horse's nostrils and the chinstrap squeezes up against the chin of the horse (acting as a brake). The degree of action of any part of the bit has to do with it's relative size.
The anatomy of each horse has a significant amount of variation. The port (center raised area) may or may not reach the roof of the mouth of every horse if the port is low as is common with a kimberwick or english style curb bit. The mouthpiece does rotate within the mouth (the purchase reflects the angle of the port and will indicate which way the port is pointing within the mouth), and with higher ported bits, it will impact and engage the roof of the mouth.
The curb bit's mouthpiece controls the pressure on the tongue, roof of the mouth, and bars. A mullen mouth places even pressure on the bars and tongue. A port places more pressure on the bars, but provides room for the tongue. A high port may act on the roof of the mouth as it touches. Some western style curbs, particularly the Spade Bit, have both a straight bar mouthpiece and a high welded port., thus acting on the bars, tongue and palate. In the wrong hands, such bits can be extremely severe, but on an exquisitely trained animal, they allow the rider to communicate with the horse with a simple touch of the fingertips to the reins.
(some information found: Price, Steven D., ed. (1998). The Whole Horse Catalog: Revised and Updated. New York: Fireside. ISBN 0-684-83995-4. Research rocks.)
