Warden, north of Bloomington sideroad is the mecca of Toronto cycling. Lots of clubs/pros use it so it, so the local car drivers are very respectful of cyclists. On weekend mornings Warden does not have much traffic, most cars going North/South use either Hwy48 or Yonge St. Old Homestead see NO traffic.

If you Drive to Aurora car-pool lot at Aurora Side Road & Hwy404, and head over to Warden, then to Pefferlaw and back you will cover 120 km.

Edit: I live on the Danforth. Round trip from the Danforth would be 200km. Starting north of the city means you only have to ride on nice country roads.