Rhythm lab
Compare the front camera (shoulders, eyes, head) with the motion sensor and see which one follows your rhythm best. Each source learns your comfortable rhythm, then reads faster as strong and slower as easy.
Collect data
Record only the tracked points (never the image) with the cadence you know is true, from a cadence sensor, a bike computer or a metronome. The file stays on this device until you download it; it is what improves the algorithm.
On the bike, use the phone screen with big buttons: /demo/cadence
Set the phone where it sees your face and shoulders, about an arm’s length away, with light in front of you. Move at a comfortable pace for 15 seconds, then speed up or ease back.
The camera image is processed only on this device: nothing is recorded or sent. The first use downloads the detection model (about 6 MB) from Google and its engine from jsDelivr. Experiment. Rhythm is relative to you; it is not RPM, power or measured effort.