In a large mixing bowl, stir together warm water, yeast and sourdough starter until the starter is dissolved. Mix in whole wheat flour and let sit for 7-10 minutes to hydrate.
Sprinkle in salt and begin adding all purpose flour. Start by adding 1 cup of all purpose flour, stirring until combined. Then add additional flour a little bit at a time until you have a shaggy bread dough. (The final amount will depend on the consistency of your starter and how humid it is.)
I like to start my kneading in the bowl to contain the mess, then turn it onto the counter once the dough comes together and starts getting a little elasticity. You can use your preferred kneading method to knead the dough into a smooth ball, about 8 minutes.
Place dough in a lightly greased bowl and cover with a damp towel and let rise until doubled in size (about 1½ to 2 hours).
To shape the dough, pat it out into a rectangle. Spread with butter, sugar and cinnamon. Roll tightly and place in greased loaf pan.
Cover with the damp towel and let rise for 1-1½ hours or until it has risen over the edge of the pan.
Brush gently with melted butter, being careful not to deflate the dough.
Bake at 450°F for 10 minutes and then at 400°F for 25-30 minutes.
When finished baking, turn onto a wire rack and cool completely before cutting.