Stir the olive oil, whole wheat flour, salt and 4 cups of the bread flour into the yeast mixture. Mix in the remaining flour, 1/2 cup at a time, stirring well after each addition. When the dough has pulled together, turn it out onto a lightly floured surface and knead until smooth and elastic, about 8 minutes. Lightly oil a large mixing bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and put in a warm place to rise until doubled in volume; about 1 hour.