Free AI Bike Fit — Analyze Your Cycling Position at Home
What is bike fitting?
Bike fitting is the process of adjusting your bicycle's geometry — saddle height, handlebar reach, and riding position — to match your body's proportions and riding goals. A proper bike fit reduces injury risk, improves power transfer, and increases comfort on long rides. Studies show most cyclists ride with at least one measurement outside the optimal range, often contributing to knee pain, back discomfort, or reduced efficiency.
I ride indoors and wanted to know if my position was actually dialed in. So I built AxyZ. You record a short video on your trainer, upload it, and it measures your saddle height, hip angle, torso lean, and pedaling stability against the same targets professional fitters work from. Then it tells you what to fix first.
It will give you a science-backed read on where you are today — and that's worth a lot when you're trying to figure out why your knee started aching after you put on a new saddle.
Read the story →Free to try · No credit card required
Cycling Position Metrics AxyZ Measures
Saddle Height
Knee angle at bottom dead center
Target 35–40° of knee flexion at BDC. Too low over-flexes the knee (above 40°) causing anterior knee pain; too high under-flexes it (below 35°) causing hip rocking and IT band strain.
Check your saddle height →Hip Angle
Hip flexion at top dead center
Target minimum 60–69° at TDC. A hip angle below 60° indicates hip flexor compression from saddle height or reach; above 69° suggests an overly upright position for the discipline.
Torso Lean
Upper body angle relative to the bike
Scored against your bike type — road, gravel, mountain, or triathlon. Asymmetry and excessive hand-loading are flagged as secondary indicators.
Pedaling Stability
Hip drop variance across a full pedal cycle
A saddle set too high forces the hip to dip on each downstroke to reach the pedal. AxyZ measures this vertical hip variance across multiple pedal cycles — the most reliable side-view indicator of saddle height overshoot.
AxyZ covers the X axis (sagittal angles — knee, hip, torso) and Y axis (vertical hip stability). The Z axis — lateral knee tracking and cleat alignment — requires multi-camera 3D capture and is the domain of a professional fitter.
How AI Bike Fitting Works
- 01Set your phone level with your pedals, 6–10 ft away. Film 10 seconds from the right side with your full body in frame.
- 02Enter your height, crank length, and bike type. AxyZ uses these to calibrate angle measurements to your specific geometry.
- 03The AI tracks every joint frame-by-frame across a full pedal cycle, scores each fit variable, and ranks the adjustments by impact.
How Accurate Is AI Bike Fitting?
AxyZ uses Google MediaPipe Pose, a computer vision model that tracks 33 anatomical landmarks at 10 frames per second. Across a 10-second video, it analyzes approximately 100 frames and averages measurements across multiple complete pedal cycles — reducing the effect of any single noisy frame.
For sagittal-plane variables — saddle height, hip angle, torso lean, and pedaling stability — a stable, level, side-on video reliably identifies whether your measurements are within target range and by how much they deviate. These are directional measurements: they tell you the right adjustment and its magnitude.
Lateral variables (cleat alignment, knee tracking, fore-aft saddle position) require a front or rear camera and 3D motion capture. AxyZ does not report on these — reporting on variables a single side-view camera cannot measure accurately would produce incorrect recommendations.
AI bike fit vs. professional bike fit — full comparison →Try first — no account needed
Free Saddle Height Check
Two photos and a playing card. We measure your inseam and current saddle height and tell you exactly how much to raise or lower it.
Check my saddle height →Last updated: · Analysis engine: Google MediaPipe Pose · Methodology