I went up there recently to go hiking, and there was a constant stream of cars going up and down that narrow road. Could be due to the cherry blossoms. It was certainly much busier than Maokong which is where I usually ride.
They may be a problem but they always beckon me.
There are a few big temples there too. If you are unlucky and there’s a religious event, the traffic will increase a lot. The few times I’ve been there (I can’t say it’s one of my most ridden roads) I didn’t feel it was worse than Satellites, Wulai, 106… Definitely better than Yangde Boulevard (weird name for a road in a mountain)
Bishan road is crazy crowded on sunny Saturday/Sunday afternoons due to the temples. During the week however much emptier vs say Satellites.. I was riding there a lot last November.
Try this for a route up Bishan Rd and FGZ - much less traffic than the main ones (via the temples), and although tis got a few steep parts, IMHO I think its a much nicer road.
This looks like Neihu Road Section 3 that @Membrillo mentioned earlier. I think double-digit gradients are fine as long as they don’t extend for more than 10 meters and are wide enough for me to zigzag my way up (hence the importance of light traffic).
Yangde is terrible for climbing but awesome for descending.
It is.
I don’t think I’ve ever climbed it fully from the bottom. There are so many other options… And I have descended it to the city very few times too. In part because it’s not the most convenient route to go down for me and in part because I don’t see the point on racing university students on scooters with little will to live.
You would love to ride with me 
. Ask @shaokilai
Three ways up BiShan, which you’ve already pointed out two
My suggestion, to unlock a new route, would be to do a counter clockwise loop via Jin Long Industrial Road.
Jin Long does have pretty amazing views towards the second half of the segment and the main benefit is you skip all the Bi Shan Temple + Cherry Blossom traffic. Downside is, it is quite steep in the first section.
Enjoy!
Thanks for the detailed directions. Looks like Jin Long Industrial Road is what Neihu Rd. Section 3 turns into. The only change I would make is I’d also like to go up (down?) to the temple for the views (gotta have the pics to show when you unlock a route, right?) before I head back over to ZhiShan Rd.