It is not the best idea to cycle to Bansko from Blagoevgrad area. There is pretty high traffic, including trucks (even on midweek, September), there is no shoulder on the road, no one would slow down. It is 22km of constant ascent, so with loaded bike it took about 2h of very bad experience. No views for most of the trip. After the highest pass, the road to Razlog/Bansko it is even more dangerous as cars & trucks are speeding, horns at you etc.
If you really need to get to Bansko probably it would be better to choose another road. Skipping this section by bus is also difficult as busses I have passed on a road are small and not suitable for carrying bicycle.