Snaffles, spades, hackamores, curbs, the list of bits is endless. But before you stick that piece of steel on your horse’s face, perhaps you should find out what it really does. Having spent over twenty years within the equine profession, I have seen every bit imaginable, and some that should have been left there.
It is incredibly important that horse people be conversant with how bits function. Many ‘bad’ equine behaviors can be traced directly to a bad bit style, fit, or use.
The vast majority of bits that you will find at your local feed store can be broadly categorized under the following categories.
Snaffles are considered by western riders as starter bits (unless they start horses in a bosal) and english riders as the go to bit. They are designed around a simple broken mouth piece with direct pull action. If you place one on your palm and pull a side it is pretty clear that a logical response would be to move away from this very direct pressure. They must be used with a cavasson, or the horse can simply evade the bit by opening it’s mouth.
Depending on how the snaffle bit is designed, horses can evade the pressure by rooting forward, which removes the pressure from the tongue and bars of the mouth and places it in the corners of the mouth.
Curbs are the western horseman’s bit of choice. They can have zero port all the way up to the elaborate Spanish spade bit. A curb bit depends entirely on the horse being neck rein broke. A neck reined horse will not be steered by the direct action of the bit, and in fact attempting to neck rein a horse not properly trained to do so causes the head to rise and the nose to face away from the direction the rider wishes to go. Again, if you lay the mouth piece across your open palm you will see that pulling one side leads to a peculiar twisting action.
This bit also has a pair of counter intuitive pressure points, first the curb part of the bit will place pressure on the top of the horse’s mouth, not the tongue. The second is a curb strap placed below the bit that rises up to meet the bottom of the jaw when the shank is lifted. Again you can see all of these actions with the bit, shorn of its bridle placed in you hand. You can do this by placing your fingers together around the bit, your thumb being the horse’s bottom jaw. When you pull on the bit you will see that if your hand wishes to avoid the pressure, up is the logical direction to go. Due to this, western horses must be carefully schooled to understand that the pressure is released when they counterintuitively drop their heads. This is also the reason that poorly broke western horses often root the sky or wear tie downs.
Hackamores and their kin, such as bosals are sometimes considered kinder because they are not in the mouth. Bosals are often used to start western horses. They are used two handed (like snaffles) and are used to shape the horse’s movement through broad, open-handed movements that mimic leading on the ground, through this the horse understands what the rules are before faced with the confusing action of the curb bit.
Mechanical hackamores have almost nothing in common with bosals. They have a nut cracker action on both the jaw and nose, and again can only be used in horses that have been finished in neck reining. They have exceptional stopping power often due to the lengths of their shanks. These bits are harder to experiment with on your hand, but by standing next to a horse wearing one you can see that the bit itself will provide almost no meaningful direction at all, and is used primarily for rating speed and stopping.
Due to the pressures exerted on the nose and the jaw, these horses too must be trained to know where to put their heads to avoid pressure.
Though there are many details that could be added to the list above, this is designed to give you a basic understanding of how these bits function. Choosing a bit should be more involved than whatever came with the horse or what your last horse wore.