ok
found it!
http://www.runbike.com/
of all things!
The RunBike has created low impact running.
Why do we need low impact running? Many runners have learned that they cannot tolerate the pounding associated with their favorite exercise. For some this means switching to less attractive exercise alternatives and venues. Ultimately this can mean less effective exercise, or even, less exercise.
The RunBike was developed to enable more people to run more miles for more years in their lives. The basis of the objective lies in two accepted realities. The first is the myriad aches, pains, and injuries associated with conventional habitual running. The second is the burgeoning body of research pointing to the medical benefits of exercise.
blah blah.. it goes on..
wle
Its really quite ingenious. Not for everyone, but I can see a use for it. An overweight person could use to get back into shape without ruining their knees. Once they got some weight off, they might not need the device. P.S. Not everyone likes riding a bike.