Frequently asked questions

Cycling activities in the FIT format from Garmin and most other head units. Files that import into Garmin Connect, TrainingPeaks or Strava generally work, including gzipped exports (.fit.gz) and zip downloads from Garmin Connect. You can also upload CSV files (see below).

The file needs speed (from a sensor or GPS) for most of the ride, and power for the analysis. GPS adds the map, loop detection and the wind model. GPX, TCX and PWX files aren't supported: upload the original .FIT file instead.

CSV lets you import data from older power meters, spreadsheets, or sensors the FIT format doesn't cover, such as air speed. The first row holds the column names (any order, any case).

CSV files don't carry a date, so elapsed times are counted from when you upload unless the time column has full dates.

Open an activity, select a lap or a range on the chart, and analyze it. Enter total mass, air density and Crr, then adjust CdA until the virtual elevation profile levels out: with the right combination, each loop starts and ends at the same virtual elevation.