curb bit measurement diagram

A Little Bit About Curb Bit Measurement and Function

To understand how any given shanked or curb bit will affect your horse’s response, it’s important to understand how to measure the bit, and, what affect the measurements and the ratios of those measurements may have.

Since use of equipment that doesn’t abide by horse show rules almost always results in disqualification, it’s also important to know how to measure the shanks, bars and port to determine if your bit is legal. These rules can be found in most organizations’ rule books.

A shanked (curb) bit is any bit that produces leverage when the reins are pulled. The leverage component categorizes it as a curb bit, regardless of the mouthpiece. A curb bit has 2 main parts: the shanks (cheek pieces) and the mouthpiece. Where the mouthpiece attaches to the shank is known as the butt. This is also the point of balance in any shanked bit and the point of rotation when pressure is applied to the reins.

A bit shank can be more accurately divided into the purchase, which includes the bridle ring above the butt, and the true shank, with rein ring below the butt. The length of the purchase and the length and angle of the shank help determine the speed that the horse’s mouth, curb strap groove and poll receive the signals, directly or indirectly, from the bit, when the reins are pulled or released. It’s important to remember other design factors including bar diameter, mouthpiece angle, and port width and height play roles in the effect of the bit on the horse’s mouth.

Whenever the reins are pulled the bit revolves around the butt or balance point. As the reins are pulled the rotation of the mouthpiece causes the bridle rings to move forward of the point of rotation and the shanks to move behind the point of rotation. This movement in turn causes the curb to be tightened on the chin and the crown piece of the headstall to put pressure on the horse’s poll. As the ratio of shank to purchase changes, the leverage a rider has available changes, as does the speed of the signal.

To measure the shank, start where the headstall is attached to the bit (on the inside of the bridle ring) and continue through the butt straight to the point where the rein pressure is applied on the rein ring of the bit. The bit shown here has 8-inch shanks.

To determine the height of the port of a bit, start at the bottom of the port and measure through the middle of the port to its highest point. To measure the width of a port (tongue relief) start where the bars end and measure the distance between them.

Every bit you’ll need for starting your colts to showing your bridle horses is available and ready to ship at Dennis Moreland Tack: Handmade swivel shanked curb bits in both steel and aluminum, and, solid shanked curb bits along with snaffles, Spanish bits and gag bits are available. All bits are offered with a variety of mouthpieces.  All steel curb bits are made from high grade 4130 steel and accented with beautiful, yet very durable, hand engraved nickel silver overlay. Mouthpieces are steel with copper strips to promote salivation. If you have any questions or need help choosing a bit call 817-312-5305 or email [email protected].

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