I used to live near Finch and Islington. I used to ride down the trail by the Humber river along the lakeshore and then up the Don valley. The trouble with these trails is that you have to limit your speed. A country ride I used to take was up Weston road to Holland marsh and back down Hwy 27. I think ther are recreational rides that start in High Park on Sat mornings - maybe you can find the details in one of the many good bike shops in TO. Good luck