The #1 Reason Your Saddle Slips: Why Shims Fail and What Truly Works

You’ve tacked up, tightened the girth, and are ready for a great ride. But as you warm up, you feel it again—that slight, persistent slide of the saddle to one side.

You dismount, check your horse, and see the familiar tell-tale sign: a dry patch on one side of his withers and a sweat-soaked spot on the other.

If this sounds familiar, you’ve likely gone down the rabbit hole of trying to solve it. The most common advice? “Just use a shim.”

Shims are often presented as the go-to quick fix for unevenness. But what if they’re just a bandage on a deeper issue? What if the solution isn’t about adding a patch, but about reshaping the foundation itself? Let’s explore why your horse’s asymmetry needs a dynamic solution, not just a static prop.

The Asymmetrical Reality: Your Horse Isn’t a Perfect Mirror Image

First, let’s get one thing straight: asymmetry is normal. Just as most humans are right- or left-handed, most horses have a dominant side. This dominance often results in one shoulder being more developed, one side of the back being stronger, or a slight crookedness in their movement.

In fact, research confirms that over 80% of horses show some degree of natural asymmetry. This isn’t a flaw; it’s a fundamental aspect of their biomechanics. It only becomes a problem when our equipment—namely, the saddle—can’t accommodate this reality.

This unevenness can stem from:

• Natural crookedness: A horse’s inherent preference to bend one way more easily.
• Training imbalances: Repetitive work that develops one side of the body more than the other.
• Past injuries: Compensatory muscle patterns developed to protect a sore area.

Understanding that your horse is naturally uneven is the first ‘aha moment.’ It shifts the focus from ‘fixing a problem’ to ‘supporting a unique shape.’

The Common Fix: Why Shims Seem Like the Obvious Answer

When a saddle doesn’t sit evenly, shimming seems logical. A shim is essentially a pad—made of foam, felt, or gel—that you insert between the saddle pad and the saddle to fill a gap. If the saddle is low on the right, you add a shim on the right. Simple, right?

Shims can provide a temporary lift and are often used by saddle fitters as a diagnostic tool or a short-term aid for a horse rapidly changing shape. But while they address the symptom—the empty space—they often fail to address the root cause and can even introduce new problems.

The Hidden Downside of a Static ‘Prop’

Imagine putting a piece of thick cardboard inside one of your shoes to correct a slight imbalance in your stride. It might lift your foot, but you’ll almost certainly feel the stiff edge of the cardboard digging into your sole with every step.

This is the core issue with shims. Static shims can create pressure points at their edges, particularly during dynamic movement. As your horse bends, flexes, and extends, their back muscles are constantly changing shape. A rigid shim doesn’t adapt with them.

It creates a hard, unforgiving edge that concentrates pressure on a small area and can lead to soreness, restricted movement, and even behavioral issues. We have to think beyond simply ‘filling a gap.’

Is the Saddle Slipping, or Is Your Horse Communicating?

For years, riders have blamed a slipping saddle on poor fit or a crooked rider. While those can be factors, groundbreaking research points to a much deeper cause.

A significant study in the Equine Veterinary Journal revealed that saddle slip is more often correlated with hindlimb lameness or underlying asymmetry than with poor saddle fit alone.

This is a game-changer. The saddle slip isn’t the problem; it’s a symptom. Your horse’s uneven push from behind may be causing the saddle to shift. Trying to hold it in place with a shim is like muffling a fire alarm instead of putting out the fire. It ignores the crucial information your horse is giving you.

For a deeper dive into this topic, our guide on What is Asymmetry in Horses? explores the causes and signs in detail.

A Dynamic Solution: Adjusting the Foundation Itself

If shims are a static patch, what’s the alternative? The answer lies in a saddle that can be molded to your horse’s unique shape—the principle behind fully adjustable, wool-flocked panels.

Instead of adding an external piece, a skilled saddle fitter can adjust the flocking inside the saddle panels. This isn’t about propping up one side; it’s about re-sculpting the entire weight-bearing surface to become a mirror image of your horse’s back.

Think of it as the difference between an off-the-rack suit and a tailored one. The tailored suit is shaped to fit you, not just padded to fill gaps.

How Fully Adjustable Panels Create True Harmony

A saddle with adjustable panels offers a far more integrated solution. Adjusting the core panel volume allows for a gradual, supportive contour that mirrors the horse’s musculature. This approach provides several key advantages:

1. No Hard Edges: Because the adjustment is made within the panel itself, there are no artificial edges to create pressure points. The entire surface remains smooth and forgiving.

2. Dynamic Support: High-quality wool flocking is resilient and responsive. It moves with the horse, flexing and yielding as muscles engage and release.

3. Adaptability: As your horse’s training progresses and their muscles develop, the panels can be readjusted. A fitter can add, remove, or shift the flocking to match their new shape. This makes the saddle a long-term partner in your horse’s development.

It’s this philosophy that drives innovations like the Iberosattel Comfort Panel, which is designed specifically for this kind of micro-adjustment to support the horse’s anatomy without creating pressure.

Frequently Asked Questions (FAQ)

Are shims always a bad idea?
Not necessarily. They can be useful as a temporary measure—for example, if a horse is recovering from an injury and has significant muscle atrophy on one side. However, they should be considered a short-term tool under the guidance of a professional, not a permanent solution.

How do I know if my horse is asymmetrical?
Look for clues like uneven sweat patterns, a saddle that consistently slips to one side, difficulty picking up one canter lead, or a trainer who constantly tells you you’re crooked (it might be your horse pushing you that way!). Our article on The Biomechanics of Saddle Pressure can help you identify subtle signs.

Can any saddle with wool panels be adjusted for asymmetry?
Most can, but the degree of adjustability depends on the design of the panel (the gusset depth, shape, and flocking access points). Saddles specifically designed for broad, dynamic adjustment offer the most effective and lasting solutions.

How often should my saddle’s panels be checked?
It’s good practice to have your saddle fit checked by a qualified professional at least once a year, or more frequently if your horse is in heavy work, changing shape, or you notice any new issues.

Your Next Step: From Awareness to Action

Recognizing that your horse’s asymmetry requires a more thoughtful solution than a simple shim is the first major step toward building a better partnership. You’ve moved from treating a symptom to understanding the underlying cause.

The goal is not to force symmetry but to create harmony with the horse you have today. By choosing equipment that can adapt and mold to your horse’s unique body, you’re not just improving saddle fit—you’re improving communication, comfort, and performance.

Continue your journey by exploring how saddle design directly impacts your horse’s freedom of movement. True comfort is the foundation of everything we do in the saddle.