The types of bits cause much confusion to the beginners. I will cover the five groups of bits and how they are used.
In this post I will give the common names and uses of bits. The oldest manuals that have survived the ages were written by the Greek cavlary commander, Xenophon (430-356BC). These writings extend remarkable to present day equestrians.
Snaffle bit are divided into several groups. The jointed mouth piece, with either a single central joint or with a link joining the two sides of the mouthpiece together and the straight-bar or mullen mouth which has a curve that is generally curved up and away from the tongue. Further groups occur regarding the cheeks or rings employed such as loose rings or eggbutts. Of these groups the mullen mouth is the mildest in its affect especially if it is thick and made of rubber or plastics that are currently being used. The straight bar is far more salutary in its action and can act strongly on the edges of the tongue and the bars. There is a similarity in the use of the jointed snaffle but the action is somewhat altered if a thick mouthpiece is used. The joint also acts somewhat like a port in a curb bit. When a centered link is added to the mouthpiece, it will lay on the tongue which will reduce the "nutcracker" action. These bits are called Dr. Bristol or French link snaffle bits. Recently trainers have become more aware that some horses have a shallow tongue groove and are uncomfortable with straight bars bits or even jointed bits. Therefor, we see bits such as the Pee Wee bit which is a mullen mouth bit that lays forward in the horses mouth and allows a lot of room for the tongue. Last we will look at the cheeks on snaffle bits. Loose rings of various sizes are employed. These rings pass through holes in the mouthpiece. Larger rings are most generally used by fox hunters or when turns at speed are intended. Large rings are harder to pull through the horses mouth. The eggbutt has a ring that can be round or flat but will not pass through the butt end of the bit. A side piece is added to the mouthpiece that gives more support and pinches less on the corners of the mouth. Other cheeks used are the Dee which looks just like the word sounds its principal advantage is that it gives more lateral support during turning. It is used on race horses as will as jumpers. The full cheek and fulmer cheeks are straight bars that lay along the face of the horse. It is advisable to use bit loops that attach the bar to the bridle. This will help maintain the bit's position in the mouth and also prevent the tips of the bars from snagging on objects. It also presents a prettier picture in the show ring. The main purpose of these bars is to prevent the bit from sliding through the horses mouth and assist the lateral action by pressing against the horses face.
Multi Ring Bits.
To add to some confusion on snaffle bits a more recent subdivision of the snaffle bit group are bits with multiple rings cheeks. They overlap with Pelham and curb bits. But because they do not have curb straps they must be classified as snaffle bits. What confuses most people is that they are called gag bits, elevators and American gag bits. Gag bits operate with an accentuated snaffle action to raise the head but the action of these bits do nothing to cause this. Please note that if a curb chain is added it is no longer a snaffle bit and the results desired from a snaffle bit is now that of a Pelham or curb bit if pressure is added to the jaw and poll. Perhaps this should be a sixth class of bits. Yet, this is a legitimate bit. It could be regarded as a multi-purpose bit whose action varies according to the rein position. These bits generally come with two or three rings. If the rein is placed on the top ring (center) you will have a snaffle. Almost, -- Because there is an additional top ring it is possible to get slight downward pressure on the poll. This will cause the head to lower. If the rein is placed on the lower ring, there will be increased pressure on the poll as well as pressure to the lower jaw thus even with the lack of a curb chain you will have curb action. It is also possible, on some of these bits to add a second rein creating the effect of a weak Pelham.
I should also mention the Bradoon bit. It is a snaffle bit.
This bit is also a snaffle but is used on a double bridle. It is a light bit with small rings that can be either loose ring or eggbutt styles. It is used along with a curb bit by the most sophisticated riders today. The Bradoon acts to raise the head when it it is necessary to elevate the head. Used in conjunction with the curb bit it will cause the face to be brought close to a vertical plane while allowing flexation and relaxation in the lower jaw. In other words you will achieve an "up and in effect"
Mouthpieces of snaffle bits
I get many questions on this subject. I will give some examples. However, by no means can I cover all of the contraptions that have been devised over the years. Most snaffle bits are generally round with a joint in the middle and allow the horse to move forward in a natural motion. Materials used are stainless steel, copper or mixtures of copper and stainless, plastic and rubber. There are what is called strong snaffles. Twisted wire of the thin variety should be discouraged as they are quit abusive to the animal. There are also double twisted wire and slow twisted steel that are also quite severe. Then we have roller snaffles, sometimes called Cherry Rollers bits, which encourage relaxation in the lower jaw and while are strong are not very sever. We have copper rollers which employ alternating copper and stainless steel rollers which are quite useful. The Magenis snaffle features rollers set across the tongue that is affective in keeping the horse from crossing the jaw in an attempt to evade the bit. The Scurrier bit has a serrated mouthpiece and employs a squeezing action that is considered a stopping bit. The double snaffle sometimes called the Y or W bit can cause bruising and or pinching and should not be used by any novice rider. The patented Dave Robart bits seeks to eliminate pinching that is inherent with most snaffle bits by allowing the center joint to rotate which allows it to lay flatter on the tongue thus reducing the chance of the center joint pinching the tongue. The Waterford snaffle is a series of balls that look severe but really is not . This mouthpiece helps with horses that tend to lay on the bit. All of these mouthpieces can be used in any of the cheeks mentioned above.
The Pelham bit
This bit employs one mouthpiece, a curb chain, and two pairs of reins. It Combines the elements of the double bridle which attempts to achieve the result of a double bridle. (Bit and bradoon). This bit is less demanding than the double bridle. However, cannot achieve the sophisticated action of the double bridle. Yet, this bit has its place for a number of riders and their horses. Pelham bits apply pressure to the tongue, bars, jaw and poll when the reins are attached to lower ring. When reins are attached to the center ring it acts more like a snaffle. If double reins are attached, it could be said, that it acts like a double bridle if the wrists are used properly. The action of this bit is also subject to the type of mouthpiece used. Some designs such as the Snaffle Pelham detract from the overall usefulness of the original design. Also note that the curb chain must be attached to the upper ring where the cheeks are attached.
This bit employs the use of a rope or round leather placed through the "gag runners" which are a pair of holes on each cheek piece. This will cause the rope that passes over the poll to draw the bit upward in the horses mouth. The action is governed by the riders hands. Used correctly it is not considered severe and is used universally in the sport of Polo. It is also used on event horses. As you may have guessed this bit is used where speed and powerful horses are used. It will cause the head to be placed in the correct position for the activity at hand. Its use is usually combined with either a standing martingale or a nose band of varying patterns. The most commonly used gag bit used in the USA is called the Cheltenham which is an Eggbutt snaffle with holes at the top and bottom of the cheek for the runners to pass through. There are also Full Cheek gags and loose ring Gag bits . Each employing a number number of different mouthpieces.
Hacamore or bitless bridles sometimes called nose bridles.
The term hackamore refers to bits that do not use a mouthpiece. This system originated with the Iberian horsemen. This system was also used by the early classical masters with the use of a caveson. This system was adopted by early Californian reinsmen through the Conquistadors. As currently used hackamores are a purely American device although it has been adopted by some European showjumpers. The action is quite simple as it gains control of the horse by pressure applied to the nose which is gained by leverage. On some hackamores there is curb and poll action. The power of this type of bit is derived from the length of the cheeks. Hackamores lack lateral control of the head and require opening of the hands. Side pull bits address this problem to some degree but it is still necessary to to move the head outward. The basic hackamore is comprised of a nosepiece and an adjustable rear strap of leather or chain attached to the cheeks. The nosepiece is generally padded leather or possibly sheepskin to prevent rubs. Other hackamores have nosepieces made of steel that are covered in leather, bicycle chain or cable covered with rubber or plastic tubing. Even steel rods that are not covered. You will also see Combination bits that incorporate a snaffle bit mouthpiece. These are not true hackamores. These combination bits are often set up to act as a Gag bit which first act on the nose then on the mouth to help turn the horse around a barrel or pole while the sidepull action of the shank and gag tucks the nose to the inside. Fitting of hackamore bits needs some care because if not set up properly you can callous the nose and cause chafing under the jaw. If hung to low you will inhibit the ability of the horse to breath. Heavy hands can actually cause injury because with long cheeks these bits can be very powerful.
In conclusion it is worthwhile to note that the fist bits employed were snaffle bits and are still the most widely used bit today. All of the Greek bits were snaffles with and without cheeks. For their young horses the snaffles were round and smooth or were sometimes fitted with lengths of chain like our modern bits with "keys". It was Xenophon, a Greek cavalry commander, who first wrote about the desirability of a light, sympathetic hand. "It is not the bit, but its use that results in a horse showing its pleasure so that it yields to the hand; there is no need for harsh measures; he should be coaxed on so that he will go forward most cheerfully in his swift paces." We communicate with our horses through the use of these bits. We need to think about what we are saying.