A bit does not rest on muscle. It works on the bars, that zone between the front teeth and molars where a thin mucous membrane covers the mandible. Almost nothing to cushion the pressure. A poorly chosen or badly fitted bit therefore takes its toll quickly, and often silently.
Horses do send warnings. They use quiet signals that many dismiss as temperament. Here’s how to read them, and how to judge a bit on grounds other than price.
Exactly where the bit applies pressure
A conventional bit distributes pressure across four zones:
- The bars: thin mucous membrane over bone, no protective thickness.
- The tongue: it absorbs some pressure, provided you leave it room to move.
- The corners of the lips: skin here is delicate and rubs with every rein movement.
- The palate: involved whenever the cannon rises, especially in horses with low palates.
Leverage bits (pelham, gag, weymouth) add action on the neck and curb groove. The longer the shank, the greater your hand is amplified. The Equirider bit guide breaks down the four main families and their actions.
The signals your horse is sending
No single signal proves the problem alone. It’s their repetition, or their sudden appearance in a previously sound horse, that should alert you:
- he opens his mouth the moment you take contact, or holds it ajar constantly;
- he puts his tongue over the bit, or pushes it out to one side;
- he tosses his head, especially at trot and in contact, yet stands quietly on the lunge;
- he gets behind the vertical, hides behind your hand, or pokes his nose;
- he stiffens consistently on one side and resists flexion;
- he turns his head away when you approach with the bridle;
- you see pinkish saliva, scabs, thickened corners or raw skin.
Make this a habit: after work, pull back his lip and check the corners and bars. Ten seconds. Many lesions stay invisible because you’re not looking for them, and the horse keeps working.
- It extends roughly 1/4 inch (0.5 cm) beyond the corners on each side, no more and no less.
- It creates one or two wrinkles at the corners, never three.
- It leaves room for the tongue without crushing the palate.
- Its rings, joint and articulation holes are smooth, with no burrs or obvious wear.
- The horse chews quietly, keeps his mouth closed without a tight noseband, and accepts contact.
- It is approved for your discipline and level.
Three fitting errors that cause pain
Too wide. A bit extending nearly an inch (2 cm) beyond each corner rocks back and forth. With every rein aid, it slides, pulls the corner and, if jointed, pinches skin between the ring and lip.
Too narrow. The opposite pinches constantly. The corners thicken, then crack. This happens often when you take a bit from another horse without measuring it.
Too high or too low. Three wrinkles at the corner mean continuous pull and loss of sensitivity. Too low, it hits the front teeth and invites the horse to pass his tongue over it. One or two wrinkles is the working standard.
A myth to correct: a thicker cannon isn’t automatically softer. In a small mouth with a thick tongue and low palate, a fat cannon fills the space and presses everywhere. Softness depends on the fit between the bit and the mouth you’re handling.
Single joint, double joint, and straight bar
A single joint closes into a V when both reins act together. On a horse with a low palate, the central point rises and contacts the roof. A double joint removes this V and spreads pressure between tongue and bars. Hence its success with sensitive horses.
A straight or slightly curved cannon rests mainly on the tongue and eases pressure on the bars. A cannon with a tongue groove does the opposite. No design is universally better: they shift pressure, they don’t eliminate it.
The bit isn’t always the culprit
Before changing bits, work through this checklist:
- The teeth. Wolf teeth, caps, hooks: these are the first suspects when a horse resists contact. Regular dental checks by a vet or equine dentist will settle it in one visit.
- The saddle and back. A sore-backed horse hollows and fights the hand. The bit gets blamed for a problem metres behind it. Our article on signs of saddle misfit gives the benchmarks.
- Movement patterns. One-sided stiffness sometimes comes from elsewhere. An assessment with an equine osteopath, after your vet’s advice, completes the picture.
- Your hands. Hard hands make the gentlest bit unpleasant. Soft, following hands make supposedly severe designs acceptable.
Changing bits without checking these four areas just moves the symptom around. Some horses go through five bits in a year when a dental check would have been enough.
Bitless doesn’t mean without pressure
A side-pull applies pressure to the nose, with broad, visible force. A mechanical hackamore works with long shanks on nose, poll and curb groove: power builds quickly. Going bitless relieves the mouth, not necessarily the head.
What the rules say, and why they help
Federation regulations govern bits, and their limits serve as benchmarks even outside competition. The FFE sets a minimum cannon thickness of 10 mm in showjumping, and 12 mm for horses aged five and under in dressage and eventing. Shank length is limited to 4 inches (10 cm). Tongue ties, chains and modified bits are forbidden, and officials check horses’ mouths before and after each round.
Approved lists vary by discipline and level: more permissive in showjumping than in dressage, where bitless riding is permitted only at certain levels from 2026. Details by event appear in our summary of approved bits. If you’re preparing for a federation exam, bit families are part of the syllabus: the Galops hub sets out the essentials.
- The bit presses on thin mucous membrane over bone: the margin for error is narrow.
- Measure width, count wrinkles, inspect the corners after every session.
- Teeth, back and saddle first. The bit second.
- A thicker cannon or bitless isn’t automatically softer.
An open wound, bleeding corners, blood-tinged saliva or sudden refusal of contact need a vet, not equipment changes. Never tighten a noseband to silence a signal: you mask the problem without solving it. This article offers landmarks; it’s no substitute for professional examination of your horse.
A bit remains a tool for conversation. Correctly measured, properly placed, chosen for your horse and not the one next door, it becomes invisible. That’s the goal.
