Pelham bit

A "cowboy pelham" is a western style of loose-jawed curb bit with additional rings at the mouthpiece allowing a second set of reins to be added.

A pelham works on several parts of a horse's head, depending on which rein is applied.

The mouthpiece acts when either the snaffle or curb rein is applied and puts pressure on the bars, tongue, and lips of the horse.

The curb chain and design of the mouthpiece can alter the degree of pressure placed on the horse's mouth.

The roof of the mouth is affected if the bit mouthpiece of the pelham has a high port or if it is jointed.

A pelham is a leverage bit, meaning that it increases the force but reduces the extent of movement applied by the rider.

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.

The lower the bit is placed, the more severe it is as the bars of the mouth get thinner and so pressure is more concentrated.

Adjusted correctly, the chain links lie flat and hang loose below the chin groove, coming into action against the jaw only when the shanks have rotated due to rein pressure.

The point at which the curb chain engages varies with the individual needs of the horse, but contact at 45 degrees of shank rotation is a common default adjustment.

The pelham bit is also used for polo, when the action of a double bridle is desired, but the rider's ability to make rein adjustments is limited.

In the United States, use of a pelham bit is prevalent in hunt seat equitation, and occasionally in show jumping and eventing.

Shank designs and size are governed by the rules for various forms of competition and very considerably across disciplines from combined driving to draft horse showing.