To clean a bit with a plastic or polymer mouthpiece, wash it in warm water using a mild soap only if needed. Rinse the bit thoroughly with running water, making sure to remove any soapy residue. Use a soft towel to dry the mouthpiece and buff the cheeks or rings.

How Bits Are Measured
To find the right size bit for your horse or pony, consider both the length of the mouthpiece and the width of the mouthpiece in combination with the conformation of your horse's mouth.

Length of the Mouthpiece
Bit length corresponds to the width of your horse's mouth. This measurement is usually provided in inches and fractions of an inch, such as 5 inch or 5 1/2 inch.

When attached to an appropriately adjusted bridle, a bit should rest comfortably at the corners of a horse's mouth and shouldn't press too hard against a horse's face. This would indicate the bit length is too short, and the horse may feel pinching at the sensitive corners of his mouth.

Conversely, if you see a 1/2 inch or more on each side between the lips and bit rings, the bit is too long. A bit that is too long can slip sideways in a horse's mouth, becoming ineffective and causing soreness.

The specific type of bit you choose will influence slightly the desirable bit length. A full cheek snaffle, Pelham or elevator bit should sit snuggly next to your horse's cheeks, but should not squeeze or pinch. For a loose ring snaffle or any bit with moveable rings, make sure that your horse's lips completely clear the bit ring holes by 1/8 inch on each side. Otherwise, the horse's skin can become pinched into the holes as the action of the loose rings works with the reins.

Measure your horse's mouth to determine the length of bit required in either of two ways:

• A Bit Sizer, simple but accurate, is a plastic device that measures in inches and corresponds to bit sizes. Take the reading as you would on a ruler. Slide the Bit Sizer across the horse's tongue, resting it against the corners of his mouth. The end piece should rest against one cheek comfortably. At the other side, read the inch measurement at the corner of the mouth.
• Use a piece of string in place of a Bit Sizer if your horse will cooperate. Mark the spots on the string that meet the corners of the horse's mouth, then lay the string against a ruler to obtain your bit length measurement.

As described previously, depending on the type of bit you're selecting, you may want to add 1/4 to 1/2 inch to your measurement.

Width of Mouthpiece
Bit width refers to the bit circumference at the widest part of the mouthpiece. This measurement may be in inches or millimeters.



For most horses, the thinner the bit, the more severe its action is on the horse's mouth because the pressure from the bit is exerted on a narrower surface. Similarly, in general, the thicker the bit, the more gentle its action on the horse's mouth because the pressure is distributed over a wider surface. With this in mind, also consider the conformation of a horse's mouth when choosing bit width. A bit should never be too thick in relation to the space in a horse's mouth.

The height of the palate (roof of the mouth) plus the thickness of the tongue determines the amount of space available for the bit. You can usually identify the conformation of the horse's mouth by prying open the side of the lips. A small or average sized tongue lies below or level with the bars of the mouth; a thick tongue rises above the bars or spills over the bars and between the teeth.

Your equine dentist, veterinarian or a knowledgeable trainer can help you determine whether your horse's palate is normal or high, which could allow for a thicker bit, or very low, which could reduce the thickness of the bit that may be used.