Correct curb (chin strap) adjustment on curb or leverage bits is critical for safety (stopping your horse) and is also important for proper function of not only the bit and curb but the entire bridle. A curb must be attached to the cheek piece rings or curb rings of the bit. It must never be attached to the snaffle rein rings on a bit with shanks and must not be too loose or too tight. In addition to safety, proper curb adjustment will allow your horse to respond to your cues accurately.
Curb adjustment is correct when the horse gets a signal from the bit as the reins are pulled (feels the bit begin to move) before the curb contacts the chin. For safety be certain the curb makes contact when you pull the reins. This contact generally occurs within approximately 3 inches of pull on the reins or an approximate 25 to 30 degree change in angle of the shanks after pulling the reins. A good rule of thumb: you should be able to slip a finger or 2 between the curb and chin if adjusted correctly. Always double-check before mounting by pulling the reins to see that the curb will make contact with the chin within 25 to 30 degrees of shank movement.
When the reins are loose (not being pulled) the curb must lie loose. It should not make contact with the chin unless the reins are being tightened. A curb that is adjusted too tight is uncomfortable and may cause your horse to throw his head or to set his head below the vertical in an attempt to escape the constant tightness. In either situation you lose the effectiveness of the curb.
The chain of events that occur once the reins are pulled or tightened:
- Simultaneous pressure from mouthpiece on tongue, bars, lips (and possibly roof of mouth if using a bit with a jointed mouthpiece or port) and to the chin from curb.
- Rotation of the cheek piece ring forward causes pressure on the poll. This pressure along with that of the bit and curb causes a fulcrum type action to occur.
The pressure points are released when the horse slows or stops and/if the rider releases the pull, or, as the horse’s head becomes perpendicular to the ground and the horse “carries” the bit.
Riding with your curb properly adjusted will help to make your rides safer and to keep your horse happy, relaxed and ready to give you his best.