I have spoken with many riders, which is to say more than 5, who suffer with various back issues. I have read numerous posts over the last four years about how recumbents have been the answer for so many who could not ride the DF bikes. Lastly, there have been more than one Chiropractor go online and write glowing reports about how they recommend recumbents to patients suffering from back pain. While it may require more action from the gluteus max, that's not the back. Bottom line, it's his back and he's the only one who can have the final word. It would seem he has everything to gain and little to loose.