How to choose the right bit for your horse

Choosing the right bit means finding a mouthpiece whose size, material and action suit the horse’s mouth and the rider’s level. A poor choice creates tension; a good one makes the contact clearer and more pleasant for both of you. Most contact problems, however, start with the hands or the fitting, not with the bit itself.

Measuring the mouth correctly

Size comes first. A bit that is too narrow pinches the corners of the mouth; one that is too wide slides around and can injure the bars. To measure, place a piece of string or a test bit in the mouth, from one corner of the lips to the other, and note the distance. Add about half a centimetre on each side for comfort.

Common sizes range from 10.5 cm for small ponies to 14.5 or 15 cm for large horses. Brands vary slightly. If in doubt, try two neighbouring sizes. The horse must be able to close its mouth without effort, and the bit should not stick out too far beyond the corners. Look at the thickness too: a small mouth copes badly with a very thick bit.

Materials and shapes

The material affects taste and feel.

• Stainless steel: neutral, durable, easy to care for.
• Copper and copper alloys: often well accepted because they encourage salivation.
• Sweet iron: iron that oxidises slightly on the surface; its taste also encourages salivation. Dry it after use.
• Rubber or synthetic: softer, useful for very sensitive mouths, but they wear faster.

The shape of the mouthpiece matters as well. The single-jointed snaffle is the most common. A straight (mullen) or slightly curved mouthpiece acts more evenly on the tongue. A double-jointed bit with a centre piece follows the shape of the mouth more closely and reduces the “nutcracker” effect. A bit with a tongue relief (anatomical port) leaves more room for the tongue.

Olive heads (eggbutts) and loose rings are not mouthpieces but the cheeks of the bit: an eggbutt snaffle sits more still in the mouth, while a loose-ring snaffle moves more. Always start as simply as possible. A complex bit does not fix hard hands.

How the bit works

A snaffle acts mainly on the tongue, the bars and the corners of the lips. In theory, the thicker it is, the milder its action, but a bit that is too thick can be uncomfortable in a small mouth. The effect also depends on the rider’s hands: a steady, light hand is worth more than a “soft” bit with hard hands. Watch how the horse reacts in the first few minutes.

Trying and fitting

Try the bit at a standstill and then on the move. The horse should chew, salivate and accept the contact without stiffening, tossing its head or putting its tongue over the bit. Check the corners of the mouth too: a slight wrinkle is normal, an injury is not.

The bridle’s adjustment affects the bit. The cheekpieces must let the bit sit correctly without pulling the mouth upwards. A badly adjusted bridle can make a good bit uncomfortable. Also make sure the bit does not press excessively on wolf teeth or the bars.

If the horse shows discomfort (refusing the contact, head high, clenched jaw), check the hands and the fitting first before changing the bit. Changing too often prevents the horse from getting used to it. Give it several sessions to adapt to a new bit.

Signs that a bit does not suit

• The horse tosses its head as soon as you take up the reins.
• It opens its mouth wide or puts its tongue over the bit.
• It refuses to go forward or resists.
• Injuries appear at the corners of the mouth or on the bars.

In these cases, review the whole picture (bit, bridle, hands) rather than trying one bit after another.

Care and replacement

Clean the bit after every use. Check for wear: a bent or rough bit causes injuries. Replace it as soon as it shows unusual wear. A well-kept bit lasts for years. Store it somewhere dry to prevent corrosion.

Before changing the bit, check the bridle fitting as well: the guides cover each part, and you will find more practical advice on the blog. To see mouthpieces for real, have a look around the shop. A question about a particular horse’s mouth? Write to me from the contact page.

The right bit shows in a calm horse and a good contact. Take time over measuring and gradual trials: it usually works better than switching between many models. Simplicity and consistency generally give the best results.