You can upload the following file types as long as the file is 25MB or smaller and contains workout data:
You might want to use the file uploader if you have rides on your computer that are no longer on your Garmin or you have rides on Garmin Connect or another site that you would like to export and upload to Strava.
Note: Route files cannot be uploaded at this time
Uploading a Garmin file
If you have an Edge device, you'll find that the device mounts to your computer like a hard drive. All you'll have to do to get your rides uploaded to Strava is:
Navigate to /Garmin/garmin/activities
Select the file - (the end in .fit or .tcx)
Add an activity manually
If you want to record an activity on Strava without a GPS device, you can create a manual upload. Simply input all the information manually, like distance, time, activity type, etc.