See exactly what JumpOnion analyzes — start to finish, on one page.
First, a quick look inside the app. Then a complete 2Lo (double loop) diagnosis from a real practice session — the same engine that runs on every customer upload. Look through it, then decide if it's worth $49/month to your skater.
Faces mosaicked for privacy. Recorded inside the JumpOnion app during a real practice session.
Computer vision measures the jump.
Below are the metrics from one real 2Lo upload. Pose estimation extracts 33 body keypoints per frame; biomechanics turns those points into measurements that match what a coach would see — but exact, repeatable, frame-by-frame.
Not AI-generated. Computed with computer vision + biomechanics. Same numbers every time you upload the same video.
Rule engine measures. LLM translates.
A deterministic rule engine compares every metric to clean-jump targets and decides severity. Then Gemini 3 Pro turns that decision into language a parent and a 9-year-old can both act on. The LLM never invents numbers — it's an interpreter, not a judge.
This jump looks good overall. No major issues were identified.
The skater lacks the vertical impulse needed to achieve sufficient air time for a double jump. Combined with a slightly delayed arm pull, the skater runs out of time to complete the rotations in the air, resulting in an under-rotated landing.
The green "excellent" is the main verdict. The red "also noted" is where most tools stop. That's where JumpOnion starts.
Every claim is traced to a measurement.
Three evidence points support the "also noted" warnings. Not hallucination. Not guessing. If you want to challenge a claim, click through to the metric.
The diagnosis becomes a sequence.
Four off-ice drills, picked from a 54-drill catalog, ordered by when they should happen relative to the next ice session. Each drill explains why— so you know what you're fixing, not just what to do.
Metronome-Synced Takeoff
3 × 8Builds consistent, explosive vertical impulse — train your body to be a precise 'human metronome' for maximum jump height.
Kinetic Freeze-Frame
3 × 8By forcing instant 'freeze-frames' in various jump positions, this drill sharpens proprioception so you can find and hold a perfectly tight axis in the air.
Fast Arm Pull
3 × 15Targets tightening speed directly. Train the arms to snap in like a retracting tape measure the instant the blade leaves the ice.
Band-Resisted Arm Snap
3 × 12Builds explosive 'braking' power against centrifugal force. Essential for snapping into a super-tight air position when rotation is already loaded.
What the skater feels. What the parent watches.
Most AI tools forget that the people executing the fix are a 9-year-old on the ice and a parent in the stands. JumpOnion gives each of them their own page.
“The instant your blade leaves the ice, imagine your body becoming a tightly wound spring — push up, then instantly snap into a spinning top.”
Stand at the side, slightly behind the takeoff point. Watch the takeoff knee: does it fully extend upwards, like a powerful piston, or is there hesitation? Immediately after takeoff, watch the arms: do they snap to the chest in one explosive motion, or is there a visible delay?
Want this for your skater?
Every JumpOnion subscription includes unlimited jump uploads, full access to the 54-drill library, historical tracking across sessions, before/after comparison, and email support from a skating mom (me).
I tested it. Gemini misclassified a 2Lz as a Toe Loop. Gemini called an imperfect air position "perfect". LLMs hallucinate; rule engines don't. JumpOnion uses Gemini only as a translator on top of a deterministic biomechanical engine — that's what makes the diagnosis trustworthy. Read the full breakdown on the blog.
DM @cikibuilds on X or @jumponion on 小红书. I read everything.
The diagnosis, metrics, and training plan above come from a real production task (0dc3eb30, March 30, 2026). Not a mockup. Not a demo. The same engine ran on this upload as runs on every customer upload.