This is an easy network and immpossible to get completely lost. A few of the stretches you can take at high speeds, but the semi-large chunky rocks will slow you down. This is a ride I do in the middle of summer, mid day. It usually isn't too bad, unless it's really humid, which is rare. Even then we rode for over an hour. It's not for the beginners because of some of the climb, and it gets you winded if you're going fast enough.
To get to the trail head starting from Mill Ave & University:Take Mill North, over the lake. Keep on it until Priest Drive/Galvin Parkway. Take a right. Go on Galvin until McDowell. Take a right. Go until the corner of a Jaguar/Porche dealer and take it right onto College. (Dealership on right). Take that just over a mile. You'll see a stone sign for Canal Park. Take that. It's called Marigold. Park in the lot. Ride in the direction you were driving until you see trails on left. You could also go to the right and head for the big slick looking rocks. Those trails are much more tame, but still fun.
http://www.singletracks.com/item.php?c=1&i=61