The Rruga e Arbërit is a well-paved road. I drove it on a Sunday and it wasn't that busy. But I can imagine that it's different on other days. Most of the time there was a shoulder about 1m wide, except for tunnels and bridges. In tunnels you can lift your bike onto the footpath, but there is often some rubbish lying around or there are huge holes that you can fall into. Be careful.
Also very nice views and lots of stands where you can buy fruit.