Does the thickness of a bit matter?

When it comes to choosing a bit, we know that riders will quite often focus on the type of material, mouthpiece or cheekpiece first, and then find a combination that works. That’s understandable - you need to balance comfort and communication in a way that works for you and your horse! But there is another factor that can make just as much difference to your horse’s comfort and way of going: the thickness of the mouthpiece. We are often taught that thicker is kinder and thinner is harsher, and while that is true in the most basic form, the right choice depends on your horse’s mouth conformation. Plus, some horses dislike bar pressure, others aren’t keen on tongue pressure, so you may need to consider that too.

Why bit thickness matters

The main reason thickness makes a difference is pressure distribution, as mentioned in the introduction. Thicker mouthpieces can help spread the pressure they exert over a larger surface area. In theory, this will make them gentler on the horse and so is often a more obvious choice.

In turn, thinner mouthpieces focus pressure on a smaller area, which increases the intensity. That means they can offer more precision but can also be too severe in uneducated hands.

It sounds simple, but your horse’s mouth only has so much room inside, and how much space can vary a lot from horse to horse! If a bit is too thick for your horse, it can press hard on the tongue, push against the palate/roof of the mouth or crowd the oral cavity. That causes discomfort, and instead of being “kinder,” the bit becomes actively uncomfortable.

Factors to consider when choosing bit thickness

1. Your horse’s conformation

Not all mouths are built the same. Horses with fleshy tongues, low palates or small mouths may run into trouble with those thicker mouthpieces, as mentioned a moment ago. There’s also a chance that horses who have a sensitive tongue may dislike a thicker bit pressing on it. By contrast, a horse with a roomy mouth and thinner tongue may go well in a thicker bit, but it can be down to personal preference too.

Signs a mouthpiece is too thick include head tossing, gaping, fussing with the tongue or an overall sense of resistance to the contact. On the other hand, if a bit is too thin, the horse may become over-sensitive, anxious or show physical signs of bruising.

2. Discipline and rules

Competition rules also play a role. For example, British Dressage specifies a minimum mouthpiece thickness of 10mm for snaffle bits and 12mm for curbs. These rules are designed to protect horse welfare and create a level playing field. Showjumping riders or those in fast disciplines may sometimes choose thinner bits for sharper responses, provided the horse is comfortable.

3. Rider skill and preference

The rider’s hands matter just as much as the equipment. A skilled, sympathetic rider may be able to ride with finesse in a thinner mouthpiece, while a novice might find a slightly thicker bit offers more margin for error. That said, ‘beginner friendly’ does not always equal ‘thicker,’ especially if the horse’s mouth conformation makes that uncomfortable.

4. Material and design

Thickness doesn’t exist in isolation when it comes to horse comfort, as the material and design of the bit can influence how it feels to the horse. Here are some examples:

● Rubber or plastic bits tend to be thicker but are softer in the mouth.
● Metal bits can be thinner yet comfortable if designed well and made from salivation-encouraging materials like sweet iron or copper.
● Ergonomic designs that shape around the tongue may reduce the need for a very thin or very thick mouthpiece.

Choosing the right thickness

The key is to get a clear understanding of your horse’s anatomy and then balance that with what you’re aiming to do with the bit. Here are some of our top tips:

● Check your horse’s mouth. A bitting expert, qualified yard manager or vet can help assess tongue thickness, palate height and overall space.
● Consider your goals. Are you aiming for relaxation in schooling, sharper aids for competition, or something your horse can stay consistent in across everything you do with them?
● Trial and feedback. Horses tell you how they feel. If they’re fussy, resistant or inconsistent, the thickness (or fit generally) may need reviewing.
● Ask for expert advice. Experienced bitting advisors (like our founder Jodie!) have the expertise to match the right thickness to your horse’s individual needs.

Need a little bit of help deciding?

At Horse Bit Bank we know how confusing the world of bits can be. That’s why we offer free bitting advice to help you find the perfect fit. With decades of hands-on experience and in-depth knowledge of all the major bit brands, Jodie is always happy to talk through your options and guide you to the right choice for you and your horse. Our bitting advice line is 01609 765 324 or email at sales@horsebitbank.com