That's strange..I just got on my first road bike on saturday and I went riding with my friend who's an experienced rider. He helped me pick out the bike and oversaw adjustments and what-not at the shop a few weeks ago. I had no back pain even after a total 92 mile ride (including some scenic trails up a 1500ft from sea level)..I just had expected pain in the seated areas and my right knee. The seat was too high and he readjusted it...I think you should get the bike adjusted or fitted to your body more appropriately. This is my third time total on a road bike but this is my take on what is neccessary for long distance riding.