Science + Geometry
Pick Up Your Insole.
Does It Pass the Geometry Test?
There is one geometric fact about the human heel that every insole either accommodates or ignores. Here's a test you can do in 30 seconds.
Your heel doesn't go straight down. It rotates on a diagonal.
Every step you've ever taken works the same way. Your heel lands and immediately rotates — not straight up and down, but at a diagonal angle, inward and forward at the same time.
It's not a flaw. It's how the heel was built. There's a hinge just below your ankle — the joint that lets the foot rotate when it lands. That hinge doesn't run straight across your foot the way a door hinge does. It runs at an angle: tilted forward and angled toward the middle of your body.
This diagonal was precisely measured by scientists in 1941. The number has never changed, because it's anatomy, not fashion. Every human heel works this way, within a small individual range.
That diagonal is not a problem to fix. It's a design feature — how your foot absorbs shock, how your leg rotates naturally when you walk, how the muscles from your ankle through your hip are designed to fire in sequence.
The problem isn't the diagonal. The problem is the floor.
Every floor, every pavement, every road you've ever walked on is a perfectly flat, perfectly symmetric surface. And a perfectly flat surface is the worst possible geometry for a diagonal hinge. When your heel lands, it can't rotate the way it was built to. It either forces through it, or it collapses. Most feet do a bit of both. Thousands of times a day.
This is the problem that insoles were invented to solve. And this is where almost all of them get it wrong.
The Test — 30 seconds, any insole
Pick up whatever insole you have nearby. This takes 30 seconds.
- 1 Hold it at eye level and look straight at the heel end — the rounded back part, as if looking at it from directly behind your foot.
- 2 Look at the two sides. Is the inner side (the side that would face your other foot) the same height as the outer side?
- 3 Look at the bottom surface where the heel sits. Does it sit flat — or does it tilt with the inner side higher than the outer?
Both sides same height
Symmetric geometry. It treats left and right the same — but your heel's hinge runs at a diagonal. A geometry mismatch, not a quality issue.
Inner side higher
Asymmetric in the right direction. Shaped to accommodate the diagonal — not block it, not prop up the arch, but meet the heel at the angle it actually rotates on.
Almost every insole on the market is symmetric at the heel. This isn't because the designers didn't care. It's because the entire industry was built around a different theory of how the foot works — one that focused on the arch, not the heel.
Why the arch isn't the answer
The arch is where most people feel discomfort, so that's where insoles were designed to act. That's an understandable design decision. But the arch is not where the rotation starts.
The rotation starts at heel strike — before the arch even touches the surface. By the time the arch engages, the hinge has already set the starting position of your entire step. If that starting position is wrong, no amount of arch support changes it.
Think about it like a door hinge. A door swings smoothly when the hinge is lined up correctly. Now imagine bolting a wedge under one side of the door — the same height on both sides. The door might feel more stable. But the hinge is now working against a surface that doesn't match its angle. The more force you put on it, the more strain at the hinge point itself.
If you've tried arch support insoles — including expensive custom ones — and they helped a little but never fully solved it, this is almost certainly why. Right foot. Wrong location. Wrong geometry.
In 2023, a major peer-reviewed analysis concluded that the theoretical foundation of arch support — the model the entire orthotic industry was built on — was "not supported by available evidence." The review was published in Biological Reviews, one of the most respected scientific journals in the world. It didn't say arch support is dangerous. It said the theory behind it is wrong. Read the study ↗
What Landing Gear does differently
Landing Gear is not a softer insole, a firmer insole, or an insole with a higher arch. It's an insole with a different geometry — one built around the diagonal angle of the heel's hinge.
Inside the heel cup, there are two small projections — one on the inner side, one on the outer. They are not the same height. The inner projection is higher. This creates an asymmetric surface that tilts at an angle — specifically the angle of the heel's diagonal hinge.
When your heel lands on that surface, it meets a floor that was built for it. The rotation the hinge needs to make happens the way it was designed to happen. The foot loads naturally. The leg rotates correctly. The chain of movement from your heel through your knee to your hip fires in the right sequence.
You don't feel the geometry. You feel what happens when everything above the heel is working correctly instead of compensating for a mismatch.
Independent Lab Results · BioMechanica LLC · 2019
31 people. 20 high-speed cameras. Every product tested head-to-head.
Dr. Martyn Shorten Ph.D., former Director of the Nike Sport Research Laboratory, measured how far each person's heel deviated from the correct diagonal rotation with each product.
| Product | Avg. deviation | Walking correctly |
|---|---|---|
| Standard foam (inside most shoes) | 3 / 31 | |
| Best-selling arch support (symmetric) | 6 / 31 | |
| Protalus T-100 Landing Gear | 19 / 31 | |
| Protalus M-100 Landing Gear | ✓ 28 / 31 — 9 in 10 |
"No other over-the-counter insole has demonstrated statistically significant tibia–heel and tibia–arch pronation reduction through 3D motion capture. The geometry-based approach produced results the shape-based approach could not."
The floor never changed. Now you have something that did.
Pick up your current insole one more time. Look at the heel end. Both sides the same height? That's the floor problem — built into the product that was supposed to solve it.
Landing Gear passes the test. 9 in 10 people walk correctly with M-100. Put them in your shoes, take a step — your body will tell you within 30 seconds whether the geometry is right.
Ready to test the geometry
Put them in your shoes.
Take a step.
9 in 10 people walk correctly with M-100.
Not sure which model? Call us Mon–Fri 6am–5pm PT.