Here's a long ride for you. Follow 470 S and E until it ends at the Cherry Creek trail. Go north on CC to Confluence Park. (See the threads in this forum about routes to cross Arapahoe.) Head south from Confluence on the Platte trail. After you cross under Hampden, continue straight for the Bear Creek trail instead of following the Platte trail where it turns left across the bridge. Follow the Bear Creek trail to Bear Creek Lake Park. You can find your way home from there. It'll be about 80-85 miles.