Just for one moment ignoring the dangers of being overly simplistic, horse bits follow the simple principle of either applying direct pressure or leveraged pressure to generate the “signal” to the horse that you want him to do something. When you pull on the rein you generate force that is transferred to the bit and with direct pressure you transfer the same amount but with leverage pressure by the law of levers you will see a multiplication in the force generated.
The humble snaffle is essentially a direct pressure bit and the term curb bit describes any bit that generates leverage. Now the force that is transferred to the bit can be distributed to the horse in different areas. The bit mouthpiece will act on the bars, tongue and the roof of the mouth. The shanks or lower cheeks work via pressure on the poll via the crown piece of the bridle, also the chin groove through the curb chain, and may also act on the sides of the mouth.
Sometimes one may need the stronger signaling of the curb but be happy 99% of the time with a simple snaffle. The Weymouth and Bradoon set can help with this however a popular solution is to look at the Pelham Bit. The Pelham has some advantage over the double bridle in that you now have two reins for direct and curb pressure but in only one bit. aBitSpecial.com has a good range of different pelham types to choose from and we offer the unique opportunity to “mix and match” your cheeks with your mouth pieces to get the results you want.
A lot of variety and function is achieved by using different mouth pieces and the variety that can be applied to the Pelham is vast. For example jointed bits which are popular with Snaffle users as they can generate a nutcracker effect on the bars of the mouth as a strong signal. Also the joint of the mouth can impact the tongue or roof of the mouth to give further signals to the horse – be very soft handed with your riding in these cases and don’t try and fix a badly schooled horse through shear brute force. That would be a very bad thing in so many ways.
To give more room to the tongue and also reduce the impact on the roof of the mouth double jointed bits are a good option. To give the tongue room but in the case where you don’t want a jointed bit you can use a ported mouth.