Well, I am officially early retirement age this year and had been walking about four miles a week at the park. My spine is a mess from my cervical to my lumbar spine. I blew another cervical disc last Fall while painting the ceilings in the house. I recently pulled out my 38 year old 3-speed Dahon and finally put new tires on it. Cardio, cardio, cardio! Wow! I had forgotten about how gravity going up a couple of the hills on my five mile route that I did twice a visit, twice a week, would put a good load on the old blood pumper. I had to zigzag the biggest hill to use gravity to help get up to the top. I then tried a six speed folding bicycle with some success but that one hill was still too much. I finally decided to roll the dice on an inexpensive Class 2 entry level Ebike and it was an answer to my prayers. Instead of two five mile laps at the park, I do two seven mile legs from my home to the park and park to my home twice a week. That one hill is no longer my archnemesis and I only use the pedal assist for about 10% of my ride so the battery is still reading full after 28 miles. Rock on, E-bikers, Rock on!