Why I Don’t Fit Double Bridles (And Why Requiring Them in Competition Makes No Sense)

In the equestrian world, double bridles are often treated like a badge of honor. They appear in upper-level dressage, in certain competition requirements, and are frequently associated with the idea of refinement and advanced communication.

But as someone who fits bits professionally and spends a lot of time studying the anatomy and biomechanics of the horse’s mouth, I simply don’t fit them.

And the reason is very straightforward.

Most horses do not have the anatomical space to comfortably accommodate two bits in their mouth.

What the Science Says About Space in the Horse’s Mouth

In 2022, a study examining the oral dimensions of adult horses measured the available space inside the mouth where a bit sits. Researchers found that horses had, on average, space for approximately a 14 mm thick bit before the tongue becomes compressed between the upper and lower jaws.

Let that sink in for a moment.

Fourteen millimeters.

Now consider what a double bridle actually contains.

A double bridle places two bits in the mouth simultaneously:

• a bradoon (essentially a snaffle)

• a curb bit

Even when using “thin” versions of both, the combined thickness often exceeds what the average horse’s mouth can comfortably accommodate.

Many commonly used bits on the market today are 15 mm or thicker on their own. When you place two of them in the mouth, you are very likely exceeding the available space identified in anatomical studies.

When that happens, the tongue must go somewhere.

Usually it gets compressed.

The Tongue Is Not Empty Space

One of the biggest misconceptions I see in the industry is that the horse’s mouth has plenty of room for equipment.

It doesn’t.

The tongue occupies the majority of the oral cavity where the bit sits, and research has shown that it is the structure that most consistently interacts with the bit and receives pressure from it.

When you add multiple mouthpieces, the tongue is often forced downward or compressed between the mandible and palate.

That pressure can affect:

• comfort

• swallowing

• breathing

• willingness to accept contact

And it can contribute to many of the behaviors riders label as “training issues.”

Requiring a Double Bridle Is Philosophically Backwards

This is where I start to question the logic of competition rules.

Dressage, at its core, is supposed to represent a horse becoming lighter and lighter to the aids. The entire training scale moves toward subtlety, balance, and minimal interference.

So why would the end goal of that training be more metal in the mouth?

If a horse is truly educated to respond to refined aids, the equipment should become simpler, not more complex.

Requiring a double bridle as a standard for advanced riding sends the opposite message.

It suggests that progression in training is measured by adding hardware, rather than by improving communication.

There Is Surprisingly Little Research Supporting Double Bridles

One of the things that surprised me most when I started digging into the science of bits is how little research exists specifically on double bridles.

There are studies on:

• bit pressure

• oral lesions from bits

• oral dimensions

• rein tension

• bit position inside the mouth

But very little research that demonstrates a clear welfare or performance benefit from placing two bits in the horse’s mouth simultaneously.

In fact, research examining ridden horses has shown that oral lesions associated with bits are extremely common, suggesting that bit pressure can frequently cause tissue damage when poorly fitted or used excessively.

When we know the available space is limited, adding additional mouthpieces without strong scientific justification becomes hard to defend.

“But Riders Need Two Reins”

This is another argument I hear frequently.

Riders often say the double bridle allows independent communication through the snaffle and curb.

But from a mechanical standpoint, there are other ways to achieve similar effects without crowding the mouth.

For example:

• pelhams

• curb designs used with two reins

These can provide similar signal separation while using a single mouthpiece.

So again, the question becomes: if there are alternatives that take up less space, why insist on two bits?

My Philosophy as a Bit Fitter

My goal is always the same.

Find the least invasive option that allows clear communication.

Sometimes that is a simple snaffle.

Sometimes it is a curb.

Sometimes it is bitless.

But I have yet to encounter a situation where placing two pieces of metal in the horse’s mouth simultaneously felt like the most anatomically considerate option.

For that reason, I simply don’t fit double bridles.

Not because riders who use them are bad riders.

Not because tradition doesn’t matter.

But because the anatomy of the horse’s mouth deserves to come first.

The Question the Industry Needs to Ask

Instead of asking whether riders are capable of using a double bridle correctly, we should be asking a different question:

Does the horse actually have room for it?

Because according to the best anatomical research we currently have, the answer is often no.

Reference

Anttila, M., Raekallio, M., & Valros, A. (2022). Oral Dimensions Related to Bit Size in Adult Horses and Ponies. Frontiers in Veterinary Science.