Curb Bit - Accessories

Accessories

The curb chain or strap applies pressure to the curb groove under a horse's chin. When the shank of the bit rotates back (due to rein pressure), the cheek of the bit rotate forward since it is a lever arm. The curb chain is attached to the rings at the end of the cheek. So as the cheek moves forward, it pulls the curb chain, tightening in the curb groove. Once it comes in contact with the curb groove of the horse it acts as a fulcrum, causing the cannons of the bit mouthpiece to push down onto the horse's bars, thus amplifing the bit's pressure on the bars of the horse's mouth.

The action of the bit is therefore also dependent on the tightness of the curb chain. If the bit is used without a curb chain (very uncommon—and dangerous), it loses its leverage action. If used with a loose curb chain, it allows the shanks to rotate more before the curb chain is tight enough to act as a fulcrum and exert pressure. This extra rotation can warn the horse before pressure is exerted on the mouth, so the well-trained horse may respond faster. If used with a very tight curb chain, the bit immediately exerts leverage and increased pressure on the bars as soon as pressure is applied to the reins. Therefore, a tight curb chain is harsher, and provides less finesse in signaling the horse than a looser curb chain would.

Less often seen is the lip strap, a thin strap or light chain that helps keep the curb chain in place and also prevents the horse from grabbing, or "lipping" the bit shanks with its mouth.