While there are literally hundreds of types of bit
mouthpieces, bit rings and bit shanks, essentially there are really only two
broad categories: direct pressure bits, broadly termed snaffle bits; and
leverage bits, usually termed curbs.
Bits that act with direct pressure on the tongue and lips of
the bit are in the general category of snaffle bits. Snaffle bits commonly have
a single jointed mouthpiece and act with a nutcracker effect on the bars,
tongue and occasionally roof of the mouth. However, regardless of mouthpiece,
any bit that operates only on direct pressure is a "snaffle" bit.
Leverage bits have shanks coming off the mouthpiece to
create leverage that applies pressure to the poll, chin groove and mouth of the
horse are in the category of curb bits. Any bit with shanks that works off of
leverage is a "curb" bit, regardless of whether the mouthpiece is
solid or jointed.
Some combination or hybrid bits combine direct pressure and
leverage, such as the Kimblewick or Kimberwicke, which adds slight leverage to
a two-rein design that resembles a snaffle; and the four rein designs such as
the single mouthpiece Pelham bit and the double bridle, which places a curb and
a snaffle bit simultaneously in the horse's mouth.
In the wrong hands even the mildest bit can hurt the horse.
Conversely, a very severe bit, in the right hands, can transmit subtle commands
that cause no pain to the horse. Bit commands should be given with only the
quietest movements of the hands, and much steering and stopping should be done
with the legs and seat.
