The City of Toronto is formulating a strategy to deal with mountain biking use of trails in parks and other natural areas. They are collecting input from the public on the issue until March 7th (thursday).
You can contact the city about this here:
Jennifer Kowalski, Parks and Recreation Planner
Parks, Forestry and Recreation: Strategic Services
Metro Hall, 24th floor, 55 John St.
Toronto, ON, M5V 3C6