A Bit About Bits. Is The Snaffle The Most Dangerous Bit Of All?
In online discussions about bits, many posters will say that in the wrong hands a snaffle can be as deadly as any curb, gag or combo bit. At first glance this seems logical, after all the majority of bits are made of metal and sit on the soft and sensitive tissues inside the horse's mouth. Any application of strong or rapid pressure on those soft tissues will cause equal harm? The problem with this claim is that it doesn't stand up on closer scrutiny.
So how can we tell? A little physics will help us out. Let's imagine that instead of the horse's mouth being the surface that we are applying pressure to, we are trying to move a large rock. Yes rocks and horse's mouths have little in common. True, but the outcome we are seeking from our rock and our horse's mouth is in fact similar. We apply pressure to the rock to make it move. We apply pressure to our horse's mouth in order to get them to move their mass (their bodies), either to slow it down or to change its direction. We also use the bit to get the horse change the way it moves its mass, even if we don't want it to slow down while it does (that is go round or work in a frame), but we will leave that one for now. While the bit in the horse's mouth doesn't actually cause the changes in the how the horse moves its mass, the pressure it applies motivates the horse to use the muscles in its legs, back and neck to move its mass in order to make the pressure on its mouth go away. So for the purposes of this illustration we will assume that our horse's mouth is like a large rock we want to move. The first thing we can try on our rock, is to reach down, grab it with our hands and attempt to pick it up. Depending on how heavy the rock is, how fit and strong we are, we may be able to apply a fair bit of pulling power to that rock and may even be able to pick it up. But the maximum amount of lifting/pulling effort we can apply is directly related to how strong we are. Picking up a rock with our hands is like using a snaffle on the horse's mouth. There is a direct relationship between the amount of pressure we can apply to the horse's mouth and the strength in our arms. Once we have reached the limit of our strength we can't increase the pressure on the horse's mouth. We can change the way the pressure is delivered by reducing the diameter of the snaffle or by changing the way we apply the pressure-for example by yanking. If we move to a thinner mouthpiece we are concentrating the force that we can apply. The thinner mouthpiece reduces the surface area over which the force of the bit can be applied which means that the force applied per square centimetre of contact with the bit is increased, even though the total amount of pressure is still limited by the strength in our arms. Alternatively, we can yank the horse in the mouth which, although being limited to that maximum strength we have in our arms, can generate more force in a short period of time due to the energy released by the momentum we generate with the yanking motion. Now it's likely that if we move to the thinner mouthpiece the horse is more likely to respond quickly to the cue to move its mass the way we want because the thinner mouthpiece causes more pain and thus increases the horse's motivation to do something (like slow down) to make the pain go away. By way of example, compare carrying a 20 litre bucket full of water with a plain wire handled, to carrying the same bucket with a plastic handle. The plain wire handle will cut in to your skin, cut off the circulation and start to cause pain in your hand pretty quickly. The plastic handle by contrast, spreads the load of the water over a wider area. You'll be able to carry the bucket with the plastic handle a lot further and with fewer rests than the plain wire handle. Even if the plastic handle hurts, the pain is of a lower intensity so you can put up with it for longer than the sharp pain of the wire. That's why horses in twisted wire, chain link and ultra-thin snaffles feel lighter and seem to require less pressure to respond to their bits. It's because the pressure that is being applied is more concentrated and thus more strongly applied to the area in contact with the bit. The benefit of a snaffle with a wider mouthpiece is that it spreads the pressure from the rider's arms over a wider area, just like the plastic bucket handle. However, the downside, especially bits with heavy mouthpieces is that they can also temporarily "indent" the tongue and compromise the blood flow to the parts of the tongue and mouth with sit under and below the bit. And if used with strong or sudden pressure their weight can cause them to hit the premolars or roof of the mouth causing pain there too. So that's our snaffles - yes they can cause pain and harm, but the amount of pressure that can be applied is limited mechanically to the strength of our arms. The critical difference between our imaginary rock and a horse's mouth is that we can't hurt the rock with our pulling but we can certainly hurt the horse's mouth. Even little arms using the reins for balance can cause pain in the horse's mouth. Any time we see a horse with a gaping mouth it's a sign that it’s experiencing discomfort and very likely pain. Clamp your front teeth down over your tongue and see how comfortable it is. It’s highly likely that it's a similar sensation to what your horse feels when his tongue is squashed by a bit. So snaffles can and do cause harm, however there is a limit to the maximum amount of pressure they can apply and its directly related to the strength of our arms and how long we can keep up the pulling effort. At maximum effort it can get pretty tiring just like pulling on a rock that won't move. About that rock. We haven't been able to lift it with our arms so our next step is to get some help in the form of a lever. There are many ways we can use a lever to add power to our arms and some ways will give us more power than others. The first thing we could do is get a short crowbar, stick it under the rock and push against it. The effort we put in is the same, but now we have the crowbar increasing the amount of work our effort can achieve. Our effort is now producing more force. This is the effect of a lever. Going back to bits, our shank, Dutch gag or curb bit without a curb chain this is the effect we are having on the horse's mouth. By adding in the lever (the shank) we can increase the impact of the pressure we apply via the reins and concentrate it on the part of the horse's mouth which is in contact with the bit. We also get another pressure multiplier not available to our rock pusher, in that the bit shank applies some pressure to the horse's poll because the bridle straps prevent the shanks from rotating when we pull the reins. So our shank multiplies the amount of pressure the horse experiences in its mouth and on its poll, even though the actual amount of effort we have to expend to pull the reins is the same or even less than we would use with a snaffle. More pressure - more discomfort, more pain - our horse is even more motivated to make that pressure go away by moving its mass the way we want it to. In fact, many horses are so motivated to never ever experience the full force of the shank bit that they pick up on the little changes in rein tension, rider position and so on and respond to these changes before the bit pressure is even applied. So they feel extra light and responsive. But that "lightness" is coming because the rider is using more force. And if we consider the wrong hands argument put forward about snaffles, if a shank bit applies more pressure to the mouth, even if the rider feels like they are applying very little, it follows that when used harshly, shank bits can cause far more pain and discomfort than a snaffle. Add arm pressure at maximum volume multiplied by the lever effect of the shank and that's a lot of pain for a horse to endure. So our rock is still there. Our small crowbar has shifted it a little, but it's still sitting in our driveway and we need it gone. We can increase the amount of work we can make apply to the rock by doing two things, we can put a fulcrum under our crowbar and we can also increase the length of the bar. Depending on the height of the fulcrum we can increase the efficiency of the crowbar by providing an opposing surface against which to apply pressure to the rock, so we don't have to spend energy holding the crowbar up at the right angle. And using a longer crowbar means we can increase the multiplier effect of what strength we have in our arms. At last we can get that stone rolling. Now notice that we haven't increased the actual power available- we're still only using the same muscles we had at the start. But the output of those muscles, the amount of force we can now apply to that rock has increased by a factor of at least three and possibly more depending on the length of the crowbar and the height of our fulcrum. This type of arrangement is known as a first class lever and it is the most efficient way to increase the amount of work done (force generated) per unit of effort. Our shank bit works in exactly the same way. So back to the horse's mouth - by adding in a curb strap and adjusting the distances between the shank length (below the mouthpiece) and the cheek piece (above the mouthpiece) we make the horse's mouth an efficient fulcrum against which we can apply force. In particular, by increasing the length of the shank we can further multiply the amount of force we transmit with the reins without having to increase the amount of effort we have to apply. In fact, we can actually use less effort (use softer cues) and still apply more pressure on the horse's mouth. For each kilogram of tension we put on the reins, the shank of the bit increases the weight of that pressure on the horse's mouth by a large factor. The longer the shank (lever) the more pressure applied. As noted above, it's why horses ridden in these bits feel lighter and softer. The fallacy is believing that the cues delivered via these bits are experienced by the horse as reduced pressure. The opposite is true. No matter how "light" or "soft" you are with horse hands, if you are making contact with the horse's mouth with one of these bits you are applying substantially more pressure on the horse's mouth than the same amount of force applied with a snaffle. Now if our rock still hasn't budged, we could go to the next step and get a machine in or some more muscle power from the friends who've been standing around watching up until now. In the world of horses, this equates to combo type bits. Not only do these bits apply pressure via the lever effect of shanks, they apply pressure to the nose, under the chin, the poll and with some designs other places beside. Some combine a thin, chain link mouth piece with wire hackamore, long shanks and a curb strap - increasing the areas of the horses head on which strong and painful pressures can be applied. It's no wonder horses ridden in these contraptions will do whatever is asked to escape these pressures. The motivation to learn how to respond quickly to avoid the pain will be very high. So yes, your horse will be soft and responsive, but only because he is desperately trying to strong uncomfortable pressure on sensitive parts of his head and mouth. Back to our original statement. Yes it's true that in the wrong hands a snaffle can be an instrument of torture. No doubt about it. But it is also true that in even the best of hands, bits which increase the pressure applied to the horse via shanks, thin mouthpieces, nosebands, curb straps etc. will always cause more pain and discomfort at lower levels of rein tension than a snaffle, no matter how skilled and sensitive the rider. These bits work because they apply more force per unit of effort- you can do less because the bit does more. No matter what language we might attach to it, we can't escape the laws of physics and the fact remains, whether applied to rocks or to horses' mouths, levers mean we can achieve more force with less effort. That's a good thing for moving rocks, but we should be very mindful of what's happening when it's applied to a horse. For more information about how bits work see Chapter 10 'Apparatus' in Equitation Science, PM McGreevy & AN McLean, Wiley Blackwell, 2010