Western Bits: Force and Pressure
A pound of force does NOT equal a pound of Pressure!
Bitting is a complicated subject with hundreds of bits currently in existence. To correctly choose a proper bit for their horse, one must understand the relations between force and pressure. There is a LOT of misinformation being repeated because of this misunderstanding.
With so many bits available, It is easy to see why even the most experienced professional would be confused. The main thing to remember is that each bit is designed with a particular function in mind and sometimes for a particular horse. The proper bit is determined by many things: the age of the horse (configuration of teeth and mouth sensitivity), its breed (natural head position), its training, the experience of the rider, what the horse is expected to do, the psychology of the horse, the toughness of the horse’s mouth (tough mouths are usually caused by improper riding) and lastly, experimentation.
There is not one solution. Sometimes while training a horse, a trainer will use, or even devise, several bits determined by how the horse is responding to different cues. Often the use of a “specialty bit” will be temporary until the horse learns the desired response.
Often one hears the assertion, usually when discussing leveraged bits verses a snaffle bit, that a pound of force equals a pound of pressure. The problem with the assertion is that the person did not recall their high school physics (or their tire gauge). Many are misled into choosing the wrong bit or choosing not to have one. The western leveraged bit’s function and application is being misunderstood, and sometimes improperly used (or avoided) because many riders do not understand the difference between force and pressure.
The incorrectness of the above assertion lies in fact that pressure is measured in pounds per square inch (English system). Thus, if I were to put a one pound weight (force) on a 12×12 tile (144 square inches), the pressure exerted by the weight would be 1/144 or 0.007 pounds per square inch. Likewise, if I were to put a 1 pound weight on the heel of a high heel shoe, with a heel of say ½ inch on a side (.25 square inch) then the pressure would be 1/.25 or 4 pounds per square inch. This brings us to the bit.
The pounds per square inch (pressure) that a horse feels with a snaffle type bit will depend upon the surface area that the bit contacts within the horse’s mouth. Examine a broken snaffle bit where one pound of force is applied to the reigns. If the contact area in the horse’s mouth is 1/2 square inch, then the pressure felt by the horse would be 1/.5 or 2 pounds per square inch. So, bits with more contact area in the horse’s mouth will generally be softer or milder that a bit with a smaller contact area. Consider the twisted snaffle whose outer surface of the ridges bear on the horse’s mouth. The twisted wire reduces the service area in the mouth (for the same diameter bit). Thus, pressure applied to this bit will be applied to a smaller surface area, thus increasing the pressure per square inch. That is why a twisted wire bit is said to be more severe (more pressure) for the same amount of force on the reigns than a smooth snaffle with more bit service area.
The point that many people are trying to make by stating one pound of force equals one pound of pressure analogy, is that a leveraged bit (by use of the lever) can be harsher than the snaffle (unleveraged bit). This seems logical on the surface, but it is not true. The pressure applied depends upon many things, such as: the horse’s head position, size of the bit surface area, and to how many places the pressure is applied. Leveraged bits also work on the pole of the horse, and to the curb (jaw) so some of the pressure is exerted there. A leveraged bit with a 1 square inch surface area could exert much less mouth pressure than a twisted wire snaffle with only a ¼ inch surface area. Also, with a leveraged bit (usually ridden with loose reigns), to exert pressure, the reigns have to be moved much further than a tight reigned snaffle bit to apply pressure. Thus, with a leveraged bit, the trained horse receives cueing (communication) for action during the movement of the reigns before force is applied. I discuss the leverage bit and why one may consider one here.
Hopefully, I have cleared up some misinformation about pressure and force. Pressure is all about surface or contact area. Generally for the same style bit, the larger the surface area, the less pressure will be exerted for the same force.
I hope you can understand why ANY bit can inflict pain in the hands of an inexperienced, untrained or improperly trained, or simply abusive user. There is a current trend for people to blame the tack and especially to shift to bittless reining (hackamores or bosals) thinking they are less cruel. This may not be the best thing for one’s horse and if one is inexperienced with the bosal or mechanical hackamore (regarded by most as a very harsh tool), one may inflect more discomfort on the horse. The least discomfort from your horse will come when you learn to ride with quiet hands and the horse is taught to respond to the cues.
I would be leery of anyone that recommends a bit change without seeing your horse, watching you ride it, and being able to explain WHY they are recommending a particular bit by explaining how its function (extracting the principles) will correct your problem. It’s not just the bit, rather its the bit AND how the bit is handled. Consider the spade bit. It is probably the most complicated and heaviest bit ever devised. It is also the most elegant and sensitive. A horse is trained (correctly) with that bit for one to two years before the reigns are ever worked on this bit. But the beauty and finesse that is obtained by the trained Spanish or Californian vaquero and the properly trained horse is pure beauty without discomfort to the horse.
I have addressed the another common misconception with how the force of a leveraged bit is calculated here. I also discuss why it shouldn’t matter.
If someone says “lets try this” without a reason, it’s usually because the reasoning ain’t very good…that’s Cowboy Logic.