The Cybex 770R Recumbent Bike is the most unique bike in the industry, with three modes of operation and 9 workouts with 21 levels. Personal trainers love it in Constant Power mode. The Target-Speed bar helps drive the user to an effective training pace. Isokinetic mode is for serious athletic and rehabilitation training. And Bike mode is just like a Sunday afternoon bike ride. Ride outside or train for the Tour de France. The lowest starting level and the highest resistance. For those who never rode a bike before and those who are preparing for the Olympics, the Cybex 770R is the perfect piece of equipment to train on. The most deconditioned user or rehab patient can use it safely because of the low power input requirement (20 Watts) and... it goes up to 900 Watts. This is all possible because of the Cybex selftensioning drive. Belt tension is important because a lot of belt tension is needed to create a high power training tool. But belt tension creates drag, and drag can drive up heart rate for beginning cyclists. The answer is the Cybex self-tensioning drive