I use strava heat maps to see where people go. Some of the paved trails through the metro parks are great if you don't like cars. I've done the path by 275 - I'm not a big fan of being near a highway, but it may be an option.
Mountain bikes: Pottawatomie, Brighton, Tree farm (walled lake). There are a lot of others north of M-59. turn bike routes on in google maps to see some paths. The tight squiggly ones are the mountain bike trails.
Best recommendation - do the Saturday 6:30am Beat the Train ride through Detroit. I just love that ride.