This is an easier variant of the Xindian Loop. Instead of turning right on Pingguang Rd. turn left and continue on around to the Xiaguishan Bridge (下龜山). Head back on 9 briefly until you reach Kangyalun Rd (康雅崙). This will take you through some pleasant little hills ( a few steep parts but not bad at all) and then around until you cross the Siyuan Bridge (思源) back to Xintan Rd (新潭).
You might want to avoid this route on Sunday afternoons since the traffic back from Wulai gets pretty bad on 9. Otherwise, this is a good second ride for a beginner.