We ride this trail a lot.
Usually we take the Oak Leaf trail south to Drexel, then head north. Drexel has a quite an uphill and after you cross Lover's Lane Road it turns into Church Street. The Franklin trail appears after St. Martins road. You got to jig jog a little to find it. Then head west on it until it runs right into the Muskego trail.
The Muskego trail is a nice, pleasant trail and pretty flat. You pass by farms and parks until you get to Muskego.
Right after you pass Muskego park and cross the road, the trail appears to have been resurfaced with recycled black top. You have to work a harder to stay moving on this surface compared to the usual crushed limestone. Also stay away from the edges as it will break up and pull you off.
We took the trail all the way to the end in Big Bend. Someday I hope the trail is extended by using the We Energies access road across the street. According to Google maps this would need a bridge across the Fox River but then you'd be able to bike all the way to Mukwonago without going on busy, high speed, curvy, country highways.
Then on the way home we took Janesville Road which has a bike lane most of the way. Janesville Road has some real big hills. After Hwy 100 we pick up Forest Home Avenue and take it to the Oak Leaf Trail. This route is about 7 miles shorter but more exciting due to the traffic, especially before, around and after Hwy 100 until you get to the Oak Leaf Trail.