Hoyt Park is approximately 2.5 miles of marked, legal, singletrack, mountain bike trails. Located in teh city there are no distinct hills in this trail system. However, the winding river trail has occasional small obstacles which can be interesting enough for avid mountain bikers.
There are directional posts that identify the mountain bike trails and show the direction. Hiking trails run through the same area as the mountain bike trails frequently intersecting, so try to watch for the directional posts! The basics of the mountain bike trail consists of one loop, through a minimal section of the loop is two-way trail. The direction of the trail is counter-clockwise, so the trail nearest the river is the return trail.
Trailhead: 1800 Swan Blvd., near the entrance parking lot
Terrain: Easy to moderate mainly flat, but interesting trails that are natural-surface single-track. Some sections are a bit wide.
Fees / Permits: None
Scenery: Running through wooded area along Menomonee River.
Trail Markings: Directional posts. Distinctive one-way signs for mountain bikers and the other way for pedestrians.
There are additional legal mountain bike trails in Harley Woods, located about 3 miles from Hoyt Park. You can easily bike to the Harley Woods trails from Hoyt by taking the Menomonee River Parkway. There are also several sections of "informal" trails along the river you can check out on the way, though I'm not sure of the legal status of these other trails.