I have done the free National Bike Challenge since it started in 2012. I’m excited that Strava is now one of the apps this year. It was easy to add Strava as my app and all my rides were automatically synched. Check it out at https://nationalbikechallenge.org/. The warm-up period is underway and the Challenge officially kicks off on May 1. Their goal is 75k riders and they already have 50k.