VeloFit — Bike Fit Analyzer

A browser-based bike fitting app inspired by MyVeloFit. Point a webcam at yourself side-on while pedalling on a trainer and VeloFit performs markerless pose detection in the browser, measures your joint angles over the pedal stroke, and gives fit recommendations for several cycling disciplines. Sessions are saved locally so you can compare changes over time.

Features

• Live webcam pose tracking — MediaPipe Pose Landmarker runs entirely in your browser; nothing is uploaded.
• Joint-angle measurement — knee, hip, torso (back), elbow, shoulder and ankle angles, sampled at the key points of the pedal stroke.
• Discipline-aware fit model — Road, TT/Triathlon, Mountain and Gravel, each with its own target ranges.
• Recommendations — concrete, prioritised adjustments (saddle height, front-end height, reach/drop) with the rationale behind each.
• Reports & history — save sessions to the browser and review past results.

Running it

The app is fully static. Because webcams require a secure context, serve it over http://localhost (allowed) or HTTPS:

# from the repo root
python3 -m http.server 8000
# then open http://localhost:8000

Allow camera access when prompted. An internet connection is needed on first load to fetch the MediaPipe model and WASM runtime from the CDN.

How to capture a good reading

1. Put the bike on a trainer and place the camera directly to the side, ~2–3 m away at roughly hip height. Keep your whole body in frame.
2. Choose your discipline, tap Start camera, then Record and pedal at a steady cadence for 15 seconds.
3. Review the measured angles vs. target ranges and the recommendations, then Save to history.

Project structure

index.html        UI shell (Capture / History / About tabs)
css/styles.css    Styling
js/pose.js        MediaPipe Pose Landmarker wrapper
js/angles.js      Landmark indices + joint-angle geometry
js/fitModel.js    Per-discipline target ranges + recommendation engine
js/storage.js     localStorage-backed session history
js/app.js         Camera loop, recording, results & history wiring

Notes & disclaimer

The target ranges are based on widely cited bike-fit guidance (e.g. the Holmes 25–35° knee-flexion-at-bottom range for road) and adapted per discipline; they are configurable in js/fitModel.js. VeloFit provides general guidance from 2D camera estimates and is not a substitute for a professional bike fit or medical advice. Make adjustments in small steps.