Apple watch’s outdoor bike

Get the most accurate measurements using your Apple Watch – Apple Support

Calibrating your Apple Watch for improved Workout and Activity accuracy – Apple Support

I tried all this. I also gave it to the GeniusBar to investigate. They mailed it out and reported that it is working normal.

How can it be losing GPS but still be working normally. The accuracy is 60% which is terrible!

Did you start the bike ride as an "outdoor cycle" in the workout app?.

Exact same thing happened to me. I've tried 2 different apps, same problem regardless of the app.