Curb bit

A curb bit is a type of bit used for riding horses that uses lever action. It includes the pelham bit and the Weymouth curb along with the traditional "curb bit" used mainly by Western riders.

Kimblewicks or "Kimberwickes" are modified curb bits, and a curb bit is used in a double bridle along with a bradoon. A curb bit is, in general, more severe than a basic snaffle bit, although there are several factors that are involved in determining a bit's severity. Liverpool bits are a type of curb bit commonly used for horses in harness.

The curb bit consists of a mouthpiece, curb chain, and a shank, with one ring on each side of the purchase arm of the shank, and one ring on the bottom of the lever arm of the shank. Pelham bits add a ring for a snaffle rein, next to the mouthpiece.

A curb bit works on several parts of a horse's head and mouth. The bit mouthpiece acts on the bars, tongue and roof of the mouth. The shanks add leverage and place pressure on the poll via the crownpiece of the bridle, to the chin groove via the curb chain, and, especially with a "loose jaw" shank, may act on the sides of the mouth and jaw.

A curb bit is a leverage bit, meaning that it multiplies the pressure applied by the rider. Unlike a snaffle bit, which applies direct rein pressure from the rider's hand to the horse's mouth, the curb can amplify rein pressure several times over, depending on the length of the curb's bit shank. Shank sizes vary from the Tom Thumb (2 inches long) to more than 5 inches. The longer the bit shank, the more powerful its potential effect on the horse. For this reason, overall shank or cheek length, from the top of the cheek ring to the bottom of the rein ring, usually cannot exceed 8½ inches for most horse show disciplines.

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