Figure L6
The Bridle and the Bit
A Labelled Curb Bit, Showing Leverage
A curb is not a stronger snaffle. It is a lever: the shank turns about the mouthpiece, so a small movement of the hand produces a larger effect.
rein tension the shank rotates about the mouthpiece shank maximum 12 cm purchase the arm above the mouthpiece; cheekpiece ring at its top curb hook mouthpiece drawn end-on; it is the pivot minimum 12 mm diameter shank the arm below the mouthpiece rein ring curb chain runs under the jaw HOW A CURB WORKS A curb asks through leverage. Rein tension rotates the shank, which acts on the horse’s jaw and poll, so a small movement of the hand produces a larger effect than the same movement on a snaffle. WHAT THE RULES SET · WAWE INTERNATIONAL Curb, pelham and traditional national bits: · maximum shank length — 12 cm · minimum mouthpiece diameter — 12 mm WHERE THE CURB BELONGS Because a curb uses leverage, it belongs to a horse and rider educated enough for the rein to be used with a light contact. At the senior standard the reins are carried in one hand, and the horse is ridden from the seat and the leg; the rein confirms.
Fig. L6  ·  A Labelled Curb Bit, Showing Leverage