If Strava is linked to your Garmin, you can upload the route via your computer through dashboard > my routes > create new route. Then click the icon (upload route). Click save. The route is automatically marked as a favorite (identified by the orange star), and it should be, because only then will it be automatically transferred to Garmin Connect and then to your Garmin device.
You can also use other platforms linked to Garmin, such as Komoot or RidewithGPS, instead of Strava.
This procedure is very similar to the one above, but it offers a direct upload to Connect. On your computer, select training & planning > courses > import. After saving, the route will be automatically loaded when you start your Garmin.
Sometimes you don't have a computer nearby, but you can still do it without one! First, ensure that you can open the GPX on your mobile device. For example, email it to yourself or send it via WhatsApp. From your email or WhatsApp on your phone, tap the icon (iOS) and open the file in the Connect app. Simply save it, and you're good to go.
Photo: The good old cable method.
Let's go back about a decade when OTA (Over the Air) syncing didn't exist yet. To get a route onto your Garmin at that time, you had to use a cable. This method still works today and occasionally even comes in handy!
Connect your Garmin to your computer with a micro-USB or USB-C cable. Make sure to use a cable that supports data transfer; otherwise, your Garmin won't be recognized. Start your bike computer; you'll now find it in your Explorer (or Finder if you're a Mac user). Drag the GPX file to the Newfiles folder and eject the device properly before disconnecting it. After a reboot, the route will be on your Garmin.
Photo: Komoot's IQ app © Komoot/Garmin
Some platforms have their own IQ app for the Garmin ecosystem. This is an app that runs directly on your Garmin device. Examples include Komoot, Trailforks, and RidewithGPS. If you install these apps, you can also import routes through them. Of course, you need to import the GPX file into the respective platform first.
To install an IQ app, first install the Garmin IQ Connect Store on your phone. Search for the app and install it. Note that your Garmin must be on and paired with your phone during installation.