Hm. I didn’t realize the the Health app had added cycling. Good!
I use a third-party app that connects to Health as a data source. The app I happen to use is Ride With GPS, but there are others that will do the job as well. So I just use the app as normal for each ride, and it feeds the data into Health.
(I have several years worth of data in Ride with GPS, and once I connected it to Health it sent the entire history over)
I don’t know if Health can automatically sense if you’re cycling and just measure without your interaction, like steps. Perhaps someone else has some insight? I figure if Health requires interaction for each ride, I’d just as soon keep using Ride with GPS and let it feed the data into Health.