tapiriik is a popular syncing service that's compatible with Strava. Use tapiriik to sync your data from other platforms to Strava and vice versa
Use tapiriik with the following programs:
Garmin Connect
Runkeeper
TrainingPeaks
SportTracks.mobi
RideWithGPS
TrainAsONE
TrainerRoad
Motivato
Velo Hero
Epson RUNSENSE
Dropbox
Smashrun
pulsstory.
Single Tracker
Beginner Triathlete
Select Strava on tapiriik.com to authorize a connection to your Strava account. Choose whichever platforms you would like to sync and click "Synchronize now."
Visit tapiriik's FAQ for more information