Mouthpieces are even more complex than ever before and it can be very difficult to choose one for your horse. Here we will give some information on the different types and what action they have within the horses mouth.
Lets start by introducing some anatomical terminology to the horses mouth and the bit itself.
Direct pressure to the mouth means rather the bit has an effect on and of the internal mouth features ie the bars, palate (roof of the mouth), tongue or lips.
Indirect pressure is applied to places around the head ie the poll, jaw, nose or chin groove.
The straight bar / mullen
The mullen mouthpiece is generally slightly curved to very curved with no joints, this means that it is very kind. This bit offers an even mouth pressure over the bars, tongue and lips.
The ported
This mouthpiece is designed to specifically promote tongue relief and can come in varying heights, note not all ports are competition legal over a certain height. These bits are generally curved to follow the shape of the horses mouth and are very good for sensitive or light mouthed horses. Horses that do not respond well to tongue pressure also favour this bit as this bit will distribute pressure directly to the bars and lips.
Full mouths may not like this bit as the port may dig into a low palate.
Barrel mouthpieces
This bit has a roller barrel in the middle, most commonly made by Myler or Bombers. This allows the rider to have independent side aids by (most commonly) two ball joints. This allows the rider to affectively communicate with the horse rather than a straight bar bit that just has a pulling effect on the corners of the mouth.
The barrel also limits nutcracker action distributing pressure evenly within the mouth.
The single joint
This style of mouthpiece is over 2000 years old and is very much the most typical type of mouthpiece seen.
The single joint offers a "nutcracker" action, pressing on the bars of the mouth, pinching the tongue and lifting, potentally digging into the roof of the mouth. The straighter the cannon the more severe this bit will be.
The single joint will usually create a lifting of the head and may cause the horse to open its mouth. You should avoid strapping the mouth shut with a flash strap or alike as you will be emphasising the pressure within the mouth, especially in the roof of the mouth. If your horses opens its mouth, it is likely that the horse is objecting to this mouthpiece.
The Demi Anky joint
This bit has been developed by Neue Schule and Sprenger have a variation of this mouthpiece. At first glance this bit looks like a single joint, but the joint is curved and the cannons are shaped slightly away from the lips. So that when contact is taken up it offers an even pressure over the bars and the central joint slides down the tongue rather than into the roof of the mouth. This offers tongue relief and does not interfere with the palate.
The double joint - lozenge
Similar to a French link and often confused with it, but the lozenge or peanut is more oval in shape and smooth sided. The link can be flat or angled, such as the Neue Schule Trans-angle lozenge mouthpiece. In general a double joint works by direct mild pressure to the tongue.
The round shape reduces the amount of nutcracker action on the tongue when the contact is taken up. This makes it a good choice for horses who prefer a double-jointed mouthpiece but require less tongue pressure than a single joint.
The Verbindend has consistently helped eradicate tongue evasions, encouraging the horse to soften and relax through the jaw. The cleverly curved mouthpiece can also enhance the development of the bend for lateral work and smaller circles.
The French link
This mouthpiece is currently widely debated in the dressage rule book it is currently still legal to use at BD.
Like the lozenge the flat plate puts pressure onto thr tongue when a contact is taken up and they eliminate the nutcracker action. The bit also puts pressure on the bars and lips
The Dr Bristol
The Dr Bristol looks much like the French link, however, the plate is sat at a angle between the cannons. As a result the plate digs into the tongue.
This bit is often used to help slow down or stop with horses that like a double joint but just need a bit more encouragement to listen. The double joint reduces the nutcracker action
The waterford
This mouthpiece is characterised by numerous joints throughout the mouthpiece. The bit works on even pressure throughout the mouth and the more joints the more mobile the bit is. This is designed to stop horses leaning, snatching and grabbing the bit. It looks a harsh bit but is quite the opposite in the right hands. This bit doesn't have any tongue or bar pressure but works on the corners of the lips.
Always increase the size of the bit when using a waterford to allow all the joints to bend. If this bit is tight it will not have any effect. Equally if the bit is too large you may run the risk of pulling bobbles through the mouth and out affecting the lips.
The rollers
The general action of these bits is a loose roller that the horse can play with, distracting and concentrating busy minds. They also act like the waterford, when the horse tries to grab hold of the bit, the roller moves and they cannot lean, snatch or grab the bit.