A lot of riders think a Tom Thumb bit is a snaffle bit, and that it is a mild bit. But, it's jointed mouthpiece doesn't actually make it a snaffle, and it is a more severe bit than many people realize. Here is what you need to know about this common western curb bit.
Tom Thumbs have a jointed mouth piece and medium length shanks from 5 to 7 inches long (15 to 18cm). The headstall of the bridle attaches to the rings at the top, and a curb chain or strap attaches to the D-shaped slots. This particular bit has a copper mouth, thought to increase the saliva the horse produces, making the horse's mouth more sensitive. The curb chain is a very important part of this (and all) curb bit, and should always be adjusted properly.
Many people disagree on the severity of the Tom Thumb bit. Because it is jointed it has a nutcracker action in the mouth and combined with the leverage action provided by the shanks this could be a very harsh bit in inexperienced hands.
How it Works:
This bit is a curb or leverage bit. The rider’s signal is felt in the mouth, over the horse’s poll and on the chin through the curb strap or chain. The Tom Thumb bit is often erroneously called a Tom Thumb snaffle. But the jointed mouth piece does not make a the Tom Thumb bit, which works on leverage, a snaffle bit. The leverage caused by the shanks make it a curb bit. (To learn the difference between curb and snaffle bits read Curb and Snaffle Bits.)