I accidentally discovered this over the last few months. increased my saddle to bar drop from about .5 in to about 1.5-2 inches. I lost 25 lbs in the last 3 months. for me the flat back did not work when I was 25 lbs heavier. my thighs would touch my belly and it forced me into a curved back position. now, my back flatter and am thinking about lowering the bars a little more.