How to use a FIT file as a cycling training log
FIT is a structured file format used by cycling computers to record time, distance, heart rate, power, cadence, and other fields. Iris uses a manual import, so you do not hand over the password for another service.
Common devices and services
Typical sources include Garmin Edge / Garmin Connect, Wahoo ELEMNT / Wahoo App, Bryton Rider / Bryton Active, and COROS DURA / COROS App. A Strava “export original” download also works when the exported file is FIT. Available metrics vary by device, sensors, and recording settings.
Import a ride into Iris
Export the activity as a .FIT file, open Training in Iris, and choose the FIT import control. The browser checks the file format and CRC, decodes the activity fields, and lets you review the activity before saving. Manual FIT import is available on Free, and saved activities appear by date in the training calendar.
What is sent and retained
Iris does not upload the original FIT binary or its original filename. It sends the activity metrics decoded in the browser, plus the file size and a one-way SHA-256 fingerprint used for duplicate detection and input limits. Because the server never receives the binary, it does not decode the source FIT again. Only fallback load derived from duration and IF is recomputed by the server before storage.
How missing metrics are handled
If heart rate, power, cadence, speed, normalized power, or intensity factor was not recorded, Iris does not guess it. Internal missing-value zeros are omitted rather than presented to external AI as measurements. Training load is included only when its source and a positive value can be confirmed.
Review the record safely
Check date, duration, and distance first, then interpret sensor values together with sensor placement and calibration. A single load number cannot diagnose recovery, ability, adaptation, or injury risk. Iris keeps the FIT activity distinct from athlete-entered recovery and plan records, and shows a separate boundary for information sent to external AI.
Duplicate imports
Iris combines the one-way file fingerprint with the account owner to detect the same file again. The original FIT cannot be reconstructed from that fingerprint. Another service may rewrite the same activity into a different FIT, so review its date and distance before saving.