Posture check for the trainer
WattPose uses your iPhone camera to measure your back angle, knee extension and head position while you ride. You check for yourself whether you hold your position through long sessions, and see the minute your posture starts to slip.
Sample session
What it measures
Pose detection finds 33 body landmarks in every frame. WattPose turns them into the angles and distances a bike fit looks at too.
While you ride
Mid-interval you won't look at your iPhone. So WattPose tells you by voice when your posture leaves its target range.
A short cue when your back angle, knee or head leaves the target range. On screen, the metric turns red.
When you stand up, WattPose sees the hip rise and pauses posture metrics. At the end you see your out-of-saddle share.
The skeleton of your best session sits semi-transparent over the live image, so you see at once whether you sit more upright today.
Live
After the ride
Posture × powerNew
WattPose puts your back angle and your power on one timeline and sums up what happened.
“In minute 40 your back angle dropped by 14°. Your power fell by 25 W in the same moment.”
Collapse point
WattPose finds the minute your posture broke down. Over several weeks you watch that point move later.
“3 weeks ago: minute 25. Today: minute 45.”
Share
The form card puts score, skeleton, aero time and collapse point on one image. You also get a 10-second highlight of your skeleton as a video.
Bike-fit report
From every session WattPose creates a PDF report. It holds your seated metrics with target ranges, a posture snapshot, your back angle across the whole ride and notes for your fitter.
A professional bike fit remains the foundation of your position. WattPose is an extra tool for checking yourself: you see whether you hold the position you were set up in, and you bring your fitter data from your own sessions.
History
Form score, aero time, estimated CdA and power across all rides, with no account and no cloud.
CdA and power figures are estimates relative to your own calibration position, not wind-tunnel measurements.
How it works
Stand your iPhone upright about 2–3 m away: from the side for back and knees, from the front for knee stability and CdA.
Sit still for a few seconds. WattPose checks camera angle, distance and tilt before it measures.
Ride your workout as usual. Afterwards you get your score, collapse point, report and form card.
Privacy
Pose detection runs on the iPhone. Camera images are never stored or uploaded, and sessions live only in the app. There is no account and no cloud.
FAQ
No. Posture, collapse point, report and form card work with the camera alone. For posture × power, connect a trainer over Bluetooth or import a FIT file after the ride.
iPhone and iPad. The exact system requirements are listed on the App Store.
Angles are calculated from body landmarks that pose detection finds in the camera image. That is enough to see changes reliably within a ride and across weeks. Absolute values depend on camera position and clothing. If the camera is badly placed, WattPose shows no values.
WattPose is built for the indoor trainer. Camera and bike have to stay still for the measurement to hold.
Nothing. There are no in-app purchases and no subscription.
No. Setting up your bike is the job of a professional bike fit. WattPose adds to it as a tool for checking yourself: between appointments you see whether you hold your position, and you can take the bike-fit report to your fitter.
Camera images and posture data do not. According to Google, ML Kit, the library behind pose detection, sends technical usage and performance data such as device type and processing time. Sharing and bug reports only happen when you start them.
Free, no account, set up in a few minutes.