page_title: Pelham bit
section_title: Shank
hierarchical_section_title: Pelham bit / Action / Shank
caption_attribution_description: Galego: Cabalo en Bastabales - Galicia - Spain
context_page_description: A pelham bit is a type of bit used when riding a horse. It has elements of both a curb bit and a snaffle bit. In this respect a pelham bit functions similar to a double bridle, and like a double bridle it normally has "double" reins: a set of curb reins and a set of snaffle reins. Because it has a bit shank and can exert curb-style pressure on the horse, it is considered a curb bit. Like all curb bits, a pelham bit has a mouthpiece, shanks with both purchase and lever arms, a ring for rein attachment at the bottom of the shank, and a curb chain. But like a snaffle bit, a pelham bit also has a bit ring on either side of the mouthpiece. Like some curb bits, a pelham bit usually has "loose" shanks - hinged at the mouthpiece in the same way that the rings of a snaffle bit are hinged. When two sets of reins are used, the snaffle rein generally is wider, to help distinguish it from the curb. A "cowboy pelham" is a western style of loose-jawed curb bit with additional rings at the mouthpiece allowing a second set of reins to be added.
context_section_description: A pelham is a leverage bit, meaning that it increases the force but reduces the extent of movement applied by the rider. Unlike a snaffle bit, the curb rein can amplify the rein pressure several times over, depending on the geometry and length of the shank.  Shank lengths are 2 inches (5.1 cm) ("Tom Thumb") and longer, although most are less than 4 inches (10 cm).
  The relation of the purchase arm—the length from the mouthpiece to the cheekpiece rings—and the "shank" or lever arm—the length from the mouthpiece to the lowest rein ring, is important in the severity of the bit. A long lower shank in relation to the upper shank increases the leverage, and thus the pressure, on the curb groove and the bars of the mouth. A long upper shank in relation to the lower shank increases the pressure on the poll, but does not apply as much pressure on the bars of the mouth.
  However, longer-shanked bits must rotate back further before applying pressure on the horse's mouth than shorter-shanked bits. Therefore, the horse has more warning in a long-shanked bit, allowing it to respond before any significant pressure is applied to its mouth, than it would in a shorter-shanked bit. In this way, a longer shank can allow better communication between horse and rider, without increasing severity. This is also directly dependent on the tightness of the curb chain.
  If the bit has a 1.5" cheek and a 4.5" lower shank, thus producing a 1:3 ratio of cheek to lower shank, while the ratio of the cheek to (upper + lower) shank is 1:4, and producing 4 pounds-force of pressure on the horse's mouth for every 1 pound-force (4 newtons per newton) placed on the reins. If the bit had 2" cheeks and 8" shank (ratio of 1:4), the bit will produce 5 lbf (22 N) of tension for every one applied by the reins (5 N/N). Regardless of the ratio, the longer the shank, the less force is needed on the reins to provide a given amount of pressure on the mouth. So, if one were to apply 1 lbf (4.4 N) of pressure on the horse's mouth, a 2" shank would need much more rein pressure than an 8" shank to provide the same effect.
caption: This pelham bit, used without a snaffle rein, is essentially a curb bit
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