I hope you like rocks because the Madrone Trail is full of them! The entire route is littered with small to large rocks and will require a good eye for finding the lines and navigating over and around the rocky terrain.
Fortunately this route is pretty easy to follow. The trail is well marked and generally flows in one direction. For this reason it is not hard to ride the trail without a guide but bringing someone who knows the trail can allow you to ride and be warned of upcoming rock gardens or step ups.