I record and upload my rides from my Garmin Edge to Connect. Connect pushes to Strava and other apps such as TrainingPeaks & Rouvy. My speed and odometer are based on a speedometer sensor calibrated to the diameter of my rear wheel. What I recorded and what Strava reports are two different things. Strava does what Strava does, and I don't really care much about its output other than normalizing the elevation gain and pushing to apps that cannot connect to Connect, such as MyWhoosh. Garmin's altimeter is okay but not the best, and Strava doesn't recognize bridges (which is true for all mapping apps online I have seen). I use Strava for its social aspects, the summary reports, and push. Each has its uses and shortfalls.