Here is a Google map of a great ride you can do through the Fudekeng graveyard (Taipei Rides I) and to Nangang via Shiding. This road also eventually connects with the popular Fengguikou ride.
Update: Did this ride again last weekend (March 8). I now recommend taking Jiuzhuang Rd. (舊莊) down if you are going to Nangang. Here's a map. The loop took a little over 3 hours including a stop for breakfast at the Shiding junction. There is memorial to the Deer Hollow Incident at the junction of Dingnan Rd. (碇南) and Jiujhuang Rd.
This ride is about 45 km long and has a total of about 600 meters of climbing broken up the first climb up to Fudekeng (c. 160 meters) , a second climb to the border between Shiding and Xizhi (this is about 380 meters), and a third (160 meters) back to the top of Fudekeng.