It turns out skateboarding has a proper biomechanics literature — force plates, motion capture labs, someone who sat down and solved the ollie as a physics problem. Bolts is built on all of it. Here it is.
What each one found, and what Bolts does with it. We have said how closely we read each, because an abstract and a full text are not the same thing.
Sports Engineering 27:8
Read in full
An optimal-control model of the ollie, solved from the physics rather than from footage. It breaks the trick into six phases and eleven timing cues, and finds the fastest ollie is jumped first and tailed second — not the other way round.
In Bolts The six moments Bolts reports are six of this model's eleven timing cues — the six a camera can see reliably. The ordering test, did you jump before you popped or pop before you jumped, comes straight out of it too.
The six, straight off this page:
Journal of Applied Biomechanics
Abstract only
Force-plate measurements of the ollie. The pop puts a little over twice body weight through the board; the landing puts nearly five times body weight through the feet, and it arrives in well under a tenth of a second.
In Bolts Why landing stiffness is one of the things Bolts checks. A landing taken with straight legs has nowhere to put that.
Apunts, 100 Hz optical motion capture
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Thirty-four body markers and four board markers on real ollies. The board reaches its highest point before the skater does. Front-knee angle tracks height almost one-to-one — and more ankle plantar-flexion goes with a lower ollie, not a higher one, which is the opposite of what most people are told.
In Bolts The board-peak-before-body-peak offset, and the front-knee angle at the crouch, are both read directly. The ankle finding is why Bolts does not tell you to point your toes.
Biomechanics of the ollie
Summary only
About half the variation in how high people ollie is explained by knee-extensor strength alone.
In Bolts The reason Bolts separates technique problems from strength problems instead of telling everyone to try harder.
Wearable sensor trick classification
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Board-mounted sensors identify tricks from their rotation-axis signature rather than from a list of names, at high accuracy — and the confusions are structural, between tricks that share an axis.
In Bolts The argument for describing a trick by its measured components instead of classifying it. Bolts reads the axes and the name follows.
Sensors
Summary only
A board-mounted inertial sensor was compared against video analysis for height and airtime, and was not reliable enough for either. Video remains the reference measurement.
In Bolts Why Bolts is a camera and not a sensor you bolt to your deck.
The literature is brilliant and it is also quite small. Here is what we are adding to it.
Which is fair enough — getting a kickflip into a motion-capture lab is a big ask. It does mean the rotation tricks are open ground, so we are building that dataset ourselves, clip by clip. Every trick that comes through makes the next reading sharper.
Nobody has ever published a benchmark for skate coaching, so we started one. Our measurement accuracy is on the site, in full, misses and all — which is more than we can say for anything else in this space.
The same measurements those studies took with force plates and marker sets, from a phone propped against a kerb at your local park.