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Revolving shanks on a curb

Something else that has become popular recently, and as usual no tack shop attendant can explain the reason for it, is a curb with swivel or revolving shanks. They can be turned or rolled in relation to the mouth piece. Some say that there is no difference between these bits and one-piece curbs, but if not, why do they exist? Well, there IS a difference, of course.

In the revolving shanks bit, the mouth piece is shaped to fit the mouth cavity and the tongue and bars, and it will fit the best at the particular angle it was made to fit. So if the shanks can be rotated independently of the mouth piece, quite like the hands of a clock, the mouth piece can stay in its optimal position, but the shanks still effect the curb chain and put pressure on the tongue/bars.

Quote:

"This bit exerts poll, curb chain and bar pressure without compromising the tongue. Each side of the bit can be worked independently for finite control of the head carriage. Proven to be very helpful with horses that like to tilt their head."

This quote is from the manufacturers of one such bit, and I tend to agree with the first sentence. The curb cannot be used one-sidedly, since the pressure against the chain is what makes it work at all, and if you put pressure on one side of the chain, the chain will move to that side and even it all out.

The tilting head thing is not a bit-related problem, it''''s a riding problem. A tilting head can never be adjusted by action on the curb at all, because action on the curb, be it double or one sided, will always be evened out by the chin chain. If the rider pulls on the left rein, the left shank will move back. The upper shank on the left side will move forward, and pull on the chin chain until it has pulled around the jaw on the right upper shank, and so evens out the pressure. But this bit can in effect allow for double action sawing with both bradoon going left and right, and chin chain going left and right. But honestly, one must think about the action of it, before one buys or uses a bit like that...

But the swiveling shank, what in the world does it do? Well, this one actually beats me. The only differences I can find in this curb and a regular one-piece curb are that (1) it rattles, and (2) when using an extreme opening rein the top loop/side piece fastening turns into the cheek of the horse, and (3) there''''s another opportunity for pinching the lips. In a regular curb, the ring at the bottom of the shank will allow for the reins to move about in their direction towards the bit. Just because the shank swivels does not mean that the curb suddenly is suited for opening rein aids like it were a snaffle. So don''''t be fooled.

Curb Chain Adjustment

The use of the curb is also closely dependent on how the chin chain has been adjusted. It needs to be correctly fitted, of course, and have no roughness in it. One can even use a cover out of leather or neopren to pad or stop it from chafing or acting sharply in general. After all, it acts across the lower jaw and its two narrow ridges of bone.

Some riders use a rubber cover or gel-cushion thingie over the chain to make it chafe less, but that really shouldn''''t be necessary. The chain doesn''''t chafe by itself, and you cannot see-saw on a normal curb. If you get blisters or soreness from using the bare chin chain, there is something fundamentally wrong with your contact with the horse, and he probably feels no better inside the mouth, either.

There are leather chin chains as well, although I haven''''t really seen anyone use one, except for yours truly. I''''m not sure if they are allowed in FEI competition, but I can''''t see why not if they are only chains covered with leather, and has an actual chain running all the way through it. The gel and rubber covers are allowed on chains, so why not this...

The purpose of the chin chain is to fix the curb bit at a certain height in the mouth, and stop it from moving about when used, and to take leverage against the chin, thus pressing the tongue down with its action. It is fastened to the upper shanks of the curb, usually in the very same ring where the side pieces go. From there it runs under the chin behind the curb bit but in front of the bradoon. Hooks hang from the upper rings, and these should point with their opening to the front, or else they can catch the bradoon, or the reins or anything, and make a mess.

If the chin chain is too loosely fitted, the curb will be allowed to turn around the axis of the mouth bar until the lower shank points backwards, when reins are taut. If it is really loose, the shanks will point straight in the direction of the reins to the hand.

In that case the curb has no lever action on the mouth at all. The bit just works as any unjointed snaffle (a straight bar) and like the shanks were a mere continuation of the reins. So like that it is a fairly blunt bit. There is no harm in this, of course, but no function either. Riders who fear their horses "over reaction" to the curb adjust their chaíns like that, or kind of.

If one were to succeed in adjusting the curb chain too snugly, so that the lower shank remains parallel to the mouth of the horse when traction is put on the reins, the opposite will occur. The angle at which the rein aid will have the most action is when the shank is at a 90 degree angle to the rein, and that is about parallel to the mouth. This is also a position where the horse can try to nibble at the lower shanks, and stallions are quite prone to this. If you are really unlucky the horse could incidentally move his head so that the lower shank turns over the other way around. This can easily happen when showjumpers use the double bridle or an unjointed pelham without converters. The best way to avoid this is naturally not to use the double bridle for jumping, and use converters on the pelham. Or fit a lip strap.

The Lip Strap

is a quite forgotten old device that noone but myself uses anymore. This is what the small holes midway down the lower shanks of the curb is for. The lip strap goes from the small hole in one shank, through an extra ring in the chin chain and to the other shank, in this way hindering the shanks from moving too far away from the back of the jaw (i.e. forward). And it does not have to be adjusted more than once - you can easily put the bridle on and off without opening it.

Now back to the chain. The ideal is to adjust the chain so that the lower shanks are at a 45 ^o angle to the mouth when the reins are tauted (without firm pressure). As soon as traction on the reins make the chain go taut, the bit comes into action. The chain fixes the upper shank in relation to the lower jaw so that all action on the lower shank is translated into an equal pressure across the tongue (mouth bar) and back of the jaw (chain). One can easily imagine the tongue being the more sensitive part.

So, when we see a horse ridden with the lower shanks pointing backwards in the direction of the rein, is this then necessarily a faulty chin chain adjustment?
I would say, usually not. Many of these horses would have their bits in perfect angle to the mouth if they were ridden with a more normal rein pressure. So what is it that gives to allow the shanks to be pulled this far back?

The answer is, the tongue.

If you look inside the mouth of an unbridled horse you will find that, contrary to the belief that the tongue is a thin "neck tie" like structure coming out of the back of the mouth, the tongue is a very thick loaf-like muscle that emerges from the space between the lower rows of teeth, even quite far down. Only the tip of the tongue is thin - the part we see when the horse licks his lips, etc.

With the force of the leverage of the bit, this muscle can be compressed by the riders traction on the reins, even to the point where a normally fitted chin chain will allow the bit to "fall through" so that the shank is in line with the rein. The tongue is soft and compressible. But it is also a muscle. It needs blood flow and has nerves and can thus hurt. How nice can it be to work through a session with a steel bar pressing the tongue down and cutting of its blood supply?

Rein Pressure on the Curb

A friend and fellow worshipper in our "lightness cult" (joke) showed me a neat test the other day. She put the foot into the curb to replace the horse''''s jaw and tongue, and applied traction on the reins. We all tried it. Now that really tells you something. With the kind of contact I''''m used to riding with, the top side of the foot just felt slightly uncomfortable after a few minutes. So I moved the reins some, released and applied again. Still tolerable. But then I applied the kind of tension that one sees others ride with from time to time, and I all of a sudden understood why some riders have a hard time "getting their horses used to" the double bridle. Pain! Constant, unavoidable pain. I admire those horses who manage to cope with this, and manage to move forward into this kind of contact with just some "added leg aids".

Curb Width

Then there''''s the size of the curb width-wise. How wide a curb ought one to fit ti the horse? The really only problem with a curb that is too wide is that it sticks out at the sides and can get caught in things, and it probably moves around more since neither it nor the chain is snug all around the jaw.

The much bigger problem is when the curb is too narrow so that it presses the lips against the teeth. The top shanks also need to give clearance to the wider upper jaw so that the skin is not pressed into the bone.