How to take an aero-position photo for cycling
A useful aero-position comparison depends more on repeatable capture than on forcing the lowest-looking posture. This guide covers the front and side setup Iris uses and the questions a still photo cannot answer.
Prepare a stable setup
Start with a securely supported bike or indoor trainer and your usual phone. A tripod is optional: use a stable surface and timer, or ask someone to take the photo. Use the normal 1× camera, step back and fit the rider and bike in frame; avoid 0.5× ultrawide. Use even light so shoulders, elbows, hips, knees and ankles remain visible. Never capture while riding or on an unstable bicycle.
Set up a front photo
Keep the phone level around hip height and face the rider directly. Include both shoulders, knees, ankles and the full bicycle without clipping. This is a practical consistency guide, not an accuracy guarantee. Perspective can turn an off-centre photo into a false left-right difference, so retake a visibly angled image.
Set up a side photo
Face the visible side directly with a level camera around hip height. Repeat the same crank position, gear, hand position, clothing, camera height and distance. One photo is enough to start; two cameras or calibration tools are not required. Knee angle and knee-over-ankle offset remain reference-only and are excluded from the score and advice because the required pedal phase is unverified.
Switch between the photo plane and estimated 3D
Angles use aspect-corrected photo coordinates, with mirror-invariant shoulder and pelvic tilt. Rotate, tilt and reset the estimated skeleton; low-visibility joints use dashed lines and poorly detected points are omitted. Depth is inferred by a monocular model, not a measured body scan or CFD simulation. Separate front and side photos do not constitute calibrated 3D measurement. See the official MediaPipe coordinate specification.
Meet the image requirements
Iris accepts JPEG, PNG, WebP, and HEIC images up to 20MB. The long side must be at least 1920px, the short side at least 1080px, and the aspect ratio no wider than 3:1. The browser regenerates a JPEG and removes the source filename and embedded location metadata. The server rejects a JPEG that still contains personal metadata and stores the accepted image in private account storage.
Make comparisons repeatable
Mark the tripod position and record saddle, handlebar, and spacer settings. Change one variable at a time and capture more than one repeat. Do not compare only the score when capture conditions differ; review the displayed quality, confidence, and retake conditions as well.
Know what a photo cannot measure
The Iris score organizes still-image alignment with product-configured bands and capture quality. It is not measured CdA, watts saved, rider level, an injury diagnosis, or your personal optimal bike fit. Static and moving positions differ. Confirm a change through breathing, vision, control, and power on the road, and use a qualified fitter, dynamic measurement, field testing, or a wind tunnel when appropriate.