Open a mountain-biking .fit file — rough-terrain GPS and Grit
Mountain biking stresses the two weakest parts of a .fit file — GPS on tight technical terrain and vendor “scores” that look like measurements and are not.
Open your file
Drop your file here
a .fit file from a watch or bike computer
No account. No upload. The file is read on this device and never leaves it.
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Grit and Flow are scores, not measurements
Some Garmin units add Grit (a difficulty estimate) and Flow (a smoothness estimate) to a mountain-bike file. They are computed indices on the vendor’s own scale, in the same family as a sleep score or a training-load number — useful within one platform, meaningless compared to another brand’s, and not a physical quantity you can check. Reading them as measured values is the vendor-score trap this site keeps flagging; they belong beside your own past rides, nowhere else.
GPS is rougher here for a reason
Tight switchbacks, tree cover and rapid direction changes are exactly the conditions consumer GPS handles worst, so an MTB track is jumpier than a road ride and its distance runs a little long where the trace zig-zags. That noise is terrain, not a broken sensor, and it is why speed spikes look implausible on the technical sections.
What you get from this page
This page reads your MTB file on your device: the position and speed fields with their roughness intact, and any Grit/Flow scores shown as the vendor indices they are, clearly separated from the measured data.
In the corpus this tool is tested against, 18 activities resolved to this sport. See the full activity-type list for every sport a .fit file can declare, and open any .fit file whatever its sport.