This is the largest of the bitting groups, and perhaps the most important. There are numerous divisions within the group, and more and more variants are developed all the time.
The snaffle, generally speaking, provides a lifting action. It lifts upwards against the corners of the lips. In the past, when the primary aim was to produce flexion at the poll and mouth through the use of the curb bit, the role of the snaffle was to raise the head, neck and shoulders as a base from which to prepare the horse to work with the curb. Today riders tend to keep the use of the snaffle up to advanced levels, so the role of the bit has become more significant.
In essence, the action of the snaffle is governed by the position of the head and the relationship of the rider’s hand to the horse’s mouth. Therefore, in the early stages of training when the young horse is encouraged to move ‘long and low’, the snaffle certainly acts in a largely upwards fashion on the corners of the mouth. As the training of the young horses advances, along with the physical development and strength, the horse develops more of a working outline. The head carriage is then somewhat higher and the face is carried nearer to the vertical plane than previously. In that position the bit has less action on the corners of the mouth and more across the lower jaw, encouraging a degree of flexion in the lower jaw, and a retraction of the nose. In the more advanced outline, when the head is carried on or close to the vertical, the action is increasingly on the lower jaw. However, in both of the last two cases the rider is still able with judicious use of the hands to exert some pressure on the corners of the mouth to try and correct any faults in the outline.