Strava will send activity time, distance, and calories to Google Fit and will receive weight from Google Fit. The option to connect with Google Fit is available on the Strava app's activity save screen, by editing your profile, and under Settings > Link Other Services. Activity details will be sent to Google Fit only when the data is downloaded from the server. This happens when scrolling through the feed on the Strava app. If you want to get historical Strava activity data into Google Fit, you will need to scroll back through your 'Me' feed in the app. If you want Google Fit to have the calories from a given activity, you’ll need to tap into the activity to view the activity details.