The Predictive Runner

Distance Scaler

Recorded distance is an estimate, whatever produced it — a footpod drifts out of calibration, GPS wanders — so a marathon can cross the line reading 42.10 km. The course length is the known quantity, and the recording is what carries the error.

Drop a .fit file and either scale by a factor or type the distance the run should have been. Speed moves with it, so your average pace comes right by the same fraction. Every other byte is left exactly as it was, and the file is corrected on your device and never uploaded.

References

  1. fit-file-parser — Dimitrios Kanellopoulos and contributors, MIT. Every file here is read with it, and the FIT profile table these tools were written against — global message numbers, field numbers, scales and offsets — is the one it ships.