What a great signal for thieves too - this user has enough disposal income to have a fitness device, and is worried about being tracked, they must have good stuff.
Presumably you could filter by average speed and only get people with expensive bikes too.
You could also tell who from the public data has a private area, how long they are in it and when they leave it. You could do graph analysis to find folks on 20k bikes (correlate by zipcode) traveling at > 20mph with other folks that also have privacy areas.
If you find that > 3 of folks in that clique are close together and somewhere else, probably having a group event, many of them may not be in their "privacy area".
Anything that collects your location data is a shtshow when it comes to operational security. Even having one friend with poor GNSS hygiene can expose an entire network of relationships.
Presumably you could filter by average speed and only get people with expensive bikes too.