Commute by bike, Apple Watch

I commute by bike everyday and wonder if the Apple Watch series 3 with WatchOS 4 register the rides automatically to the health-app like it does with steps, pulse and active calories? or do I need to manually start a new bike-ride everytime (twice a day, everyday, all year) to get stats right?

Apple Watch series 3 (GPS) with WatchOS4 synced to my iPhone 7 with iOS 11.