Instructions
Put the bridle on the horse. Adjust the bit.
Count the number of wrinkles. You should have two to three wrinkles at the corner of each side of the horse's mouth. Adjust the bridle a notch, if less than two, or loosen the bridle, if more than two.
Check position of the bit. It should lie in the toothless area on both sides of the mouth.
Look at the width of the bit. It should not pitch the corner of the horse's mouth, and the entire sides should be alongside the horse's mouth. Standard width is 5 inches, but bits come considerably smaller. The average horse take a 4½ to 5-inch bit.
Ride the horse, and look for signs the horse dislikes the bit. Signs include head tossing, bit chomping, resistance and sensitivity.
Inspect the sides of the mouth immediately after riding. After a long session, you should not see any marks on the mouth. Watch for an angry red tongue. Use a wider bit if any marks appear on the side of the horse's month. Consider bit guards to protect the horse's cheek.
How to Fit Your Horse's Bit
Fitting your horse's bit is more than the size and tightness of the bit. It might not be what you want to use, but each horse is different. Bit features to consider include mouthpiece type, shank length, size, curb chain position, noseband and mouthpiece material. Each of these features vary by bit. For example, mouthpiece options include a port, snaffle and twisted metal, and each of these come with different options, such as the height of the port.