There are two types of bits: snaffle and curb. Snaffle bit is usually a straight bar hinged in the center with two rings on each outer end. There is no extra leverage to a snaffle bit. If you pull with 1 pound of force on the rain then 1 pound the force will be felt by the horse’s mouth from the bit.
Curb bits, on the other hand, have an extra length of metal from where the snaffle bit rings would normally be. This extra length of metal gives leverage. A common way to visualize this leverage is to think of a carpentry hammer. If you’re trying to pull a nail from a board with the claw end of a carpentry hammer, and the hammer handle is short, you have to exert more force. If you have a longer handled hammer then the amount of force that you have to exert on the handle would be less in order to pull out the nail.
Curb its work much the same way. Longer bar exerts more force on the mouth of the horse. This allows the rider to exert less pressure on the rains in order to get the horse to turn.
Snaffle bits do not have this extra length of iron. Snaffle bits are commonly used to train young horses to respond to pressure from a rider. Because there is less pressure on the bit, snaffle bits are considered gentler to horse.
Snaffle bits are usually hinged in the center and applies a nutcracker type action to the horse’s mouth. Both types of bits apply pressure to the bars of a horse’s mouth. The bars of the horse’s mouth is the section where there are no teeth that sits in front of the back grinding molars.
There are a variety of snaffle bits all with a different purpose. The basic types are as follows:
The O-ring: the O-ring is a simple ring that is attached to the outer ends of the bit. The ring itself is usually not fixed, but is allowed to rotate on the ends of the bit. This type of bit is considered more forgiving but has the possibility of pinching the lips of the horse. This type of bit is usually used in Dressage training.
The Dee Ring: the D ring describes the shape of the ring. The outer ends of the bit usually have a hinge that looks very similar to door hinges. The D ring itself is attached to the hinges that are on the end of the outer bit. This hinge is wider than a typical O-ring and gives a little more pressure to the mouth of the horse. Since the hinge of the D ring is usually wider than the lips of the horse pinching usually does not occur.
Full Cheek: the full cheek bit is a little different than the above two. At the very outer ends of the bit, the ring in which the reigns attach, have bars that sit perpendicular to the horse’s mouth and nose. These bars keep the bit centered in the mouth and does not allow the bit to slide out to one side of the mouth or the other.
EggButt: the eggbutt bit gets its name from the oval-shaped of the ring at the outer ends of the bit. The eggbutt bit is a cross between of the O-ring and Dee ring bits. The eggbutt bit usually is usually made thicker than the other bits. This type of bit is gentler to horse and does not pinch the horse’s lips. Some horses won’t take an eggbutt bit, as the extra thickness of the bit weighs heavy in the horse’s mouth.