You can upload up to 25 files at a time via the Strava website. Strava accepts .tcx, .fit, and .gpx files that are 25 MB or smaller.
- Save the files you wish to upload to a local folder on your computer.
- Log in to Strava.com and click the orange "plus" icon at the top-right of the screen. Choose "Upload Activity".
- After clicking "Choose files", browse to the local folder where your files are saved, and select the files you wish to upload (up to 25 files at a time).