Find routes 
Gruzo Selection
Flanders Gravel - 160 km route
159
1465
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Gruzo Selection Strava
- Open the activity on strava.com. The app can't export.
- Click ··· (the three dots) → Export GPX.
Garmin Connect
- Open the activity on connect.garmin.com.
- Click the gear icon → Export File, and drop the ZIP as it is.
That link shows gravel rides; switch the filter if you saved it as a regular ride.
Wahoo, Komoot and most bike computers export from the phone app — or copy the .fit file straight off the device.