It's not possible to upload route files directly to Strava at this time. Currently, your only options are to create a route off of another user's activity or build the route by hand using our Route Builder. There is a Strava Labs tool that allows you to upload your GPX and turn it into a Strava route, but please note that this is not technically a Strava.com feature. Strava Labs is built by our engineers, mostly using their own personal time and accessing site data using our API. And as noted at the bottom of the page "Strava Labs is where Strava engineering occasionally releases side projects independent of our product and share our processes and stories. Projects may be added, removed or break at any time, so use them at your own risk."