This is something that has been called for by the masses for awhile. While there have always been third party workarounds, this now streamlines the process and hopefully eliminates some headache.
This is a super brief guide on how to get your Garmin Connect activities to automatically sync to Strava.
Step By Step Guide to Syncing Garmin Connect and Strava
1) First head over to Strava and login (you do not need to be a premium member)
2) Click on the large orange Upload button in the top right of the screen. You will go to the screen below. Notice where it says, “Enable seamless syncing…” Click where it says, “Get Started”
4) Then you will get this screen. Of course you want to click “Connect with Garmin”
5) Which then takes you to the screen where you will authorize the process. You may have to login to Garmin Connect. After that it will ask you to “Allow Strava Access” Click on “Allow”
6) Now you should click on the large orange Upload button on the top right again and tget this screen. If setup was successful you will get this screen. You also still have the ability to upload directly from your devices.