Hellbrunner Allee

There are at least 3 long distance bike routes through Salzburg, including both one named after Mozart and one called Freisaalweg. There also appear to be a variety of local bike routes, to Morzg and to Kommunal-friedhof.
As today promised to be another scorcher at 9am I headed out to ride 4km to Hellbrunn Castle and its trick fountains. The bike paths are a mix of paved or gravel. I don't like long stretches of gravel as it causes punctures, do I rode on the street or on the sidewalk, as feasible.
I don't think Salzburg has as much bike infrastructure as major German cities have. Generally traffic behaved itself, but still too close and too fast for a consistently carefree experience.