The first few kilometers are cruel. Lane with truck traffic. Then comes an industrial area with trucks that stir up a lot of dust. Add to that slopes and old pickup trucks with diesel engines blowing out a lot of black clouds of smoke. Horrible!!! Nowhere a way to take a break in halfway beautiful surroundings. At some point, when there is no other way, we stop at a petrol station 20 km from the finish to have a drink. There you can at least sit in the shade.
The last kilometers go then. Good road with shade but still a lot of traffic.
The first 50 km of this section you can not expect bikers actually.
But good. We made it. There is no alternative on the Bulgarian side.