I have suffered from “bad knees” for many years and it is to the point that knee replacement is likely. It is that “catch 22″ in that without exercise my weight increased causing more pain and greater restricted mobility, but if I did exercise I suffered even greater pain and inflammation of the knees and in turn restricted mobility. That was until I purchased your Q47! I have not been able to perform such rigorous exercise in more than 15 years without suffering intense pain. I admit to hesitating when I was told the purchase price, but now, well how much money is it worth to be able to exercise rigorously and not suffer intense pain? The answer is a whole lot! Additionally, I suffered injury to one foot (unrelated to use of the Q47) and had to have reconstructive surgery. I was off that foot for two months, but have now worked my way back to the level of use on the Q47 I was at prior to the surgery. I was reminded of how I can exercise rigorously and not suffer the pain in my knees and just had to write! Thank you for the efforts in research and development that lead to this machine! Oh and yes I’ve used other ellipticals and there is no comparison.