Movement
Three segments, two joints
Instead of one frame trying to match the whole back at once, three short crossbars each seat on their own stretch of it. The joints between them take up the difference, stride by stride.
Patent pending · Developed in the Netherlands
The saddle tree hasn't changed in two thousand years.
Every saddle is built around a rigid frame. The horse's back is not rigid; it lifts, dips and bends through every stride. EquiWave Flex breaks the tree into three, and puts joints between them.
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Rigid tree
Load conc. — · Contact —EquiWave Flex
Load conc. — · Contact —
One rigid frame
Three segments, two joints
Bars below the line show contact load
Schematic. Illustrates the operating principle, not measured test data.
The problem
A frame that can't follow.
Underneath the leather of almost every saddle sold today sits a tree: a fixed frame of laminated wood and steel. It gives the saddle its shape, spreads the rider's weight and keeps the rider's spine clear of the horse's. It has done that job, in more or less the same form, since the second century.
The horse's back does not hold still. It flexes and extends as the back rounds and hollows, it bends through turns, and — most awkwardly for a saddle, it rotates about its long axis as each hind leg pushes off, so the left and right sides are never quite level with each other. A frame built to one fixed shape can only match that back at one moment in the stride. The rest of the time it makes contact unevenly, and saddlers have words for the results: bridging when it props on the ends, rocking when it balances on the middle.
So the flocking is left to absorb everything the tree cannot follow. That is what the wool inside the panels is really doing, squashing, unevenly, thousands of times an hour, until it packs down hardest exactly where it was working hardest and the saddle needs reflocking again. Shimming, adjustable gullets and half pads are all versions of the same compromise. All of it works around the tree. None of it changes the tree.
Why this is hard
The tree is the one part of a saddle nobody redesigns, because it is doing three jobs at once: hold the shape, spread the load, protect the spine. Take away its stiffness and it usually stops doing all three.
Treeless saddles solved the first problem by removing the frame, and inherited a new one, the rider's weight concentrates where the rider sits. EquiWave Flex keeps the frame.
The design
We kept the tree. We broke it into three.
Three crossbars, each carrying a pad either side of the spine. Two joints on the centerline link them, sitting in the gullet clear of the spinous processes. Each bar finds its own angle, so the structure follows the back instead of the flocking having to hide the difference.
Seen from the front and above
The movement that matters for a saddle is not mainly the back rising and falling. It is rotation about the long axis: as each hind leg pushes off, the ribcage rotates and the left and right sides of the back move out of phase with each other. At any instant, the back is not symmetrical.
Each crossbar takes the angle of the surface under its own pair of pads, so all six stay loaded. Switch to the traditional tree and the plate stays level, because a single rigid frame spanning both sides has no way to take an angle. Everything the horse does has to be absorbed by the flocking squashing, which is why it compresses unevenly, and why it packs down where it is worked hardest.
Load
The same weight, spread wider
Maintaining contact across more of the panel means the same rider weight is carried over a larger area. Larger area, lower peak pressure, that is the whole mechanism.
Feel
It bends and twists, not just flexes
Ball joints move in every axis, so the tree follows the back through a turn and through the twist of the canter, not only up and down. Riders in testing describe it as a closer, quieter contact.
Fit
It looks and fits like a saddle
Familiar shape, familiar flocking, familiar fitting appointment. Nothing about your routine changes, and nothing about it announces itself in the warm-up ring.
Where we are
Honestly: it isn't finished yet.
We would rather tell you exactly where this stands than dress it up. Here is the real state of things as of July 2026.
- Availability
- Not on sale. We are building the early access list now and will contact it first when riding trials open.
- Intellectual property
- The flexible tree construction is the subject of a patent application. Application number to follow.
- Testing
- Developed with input from Utrecht University. Independent pressure measurement is planned; we will publish the results here in full, including anything that doesn't flatter us.
- What we can't show yet
- Photography and video of the production saddle, and measured pressure data. The comparison above is a schematic of the principle, not a test result.
Who's building it
Twenty years in the industry, and a stubborn question.
EquiWave is a small Dutch team: more than twenty years in the horse industry between us, and enough time spent watching saddlers work around a rigid frame to start asking why the frame had to be rigid in the first place.
The mission is short enough to fit on one line, better welfare for the horse, and a rider who can feel more of what's underneath them. We don't think those two things are in tension. We think they're the same thing.
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Robert Portielje
Communications
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If you fit saddles for a living, stock them, or are looking at where this category goes next, we have a separate conversation for you, including the technical detail and the commercial terms that aren't on this page.