I’ll never be a tightrope walker, nor a unicyclist, nor a pole sitter. I’m a pretty poised guy, and I’m not particularly afraid of heights, but I do have a healthy sense of self-preservation. It has served me well so far, and I hope it continues to do so for many years to come.
But not everyone feels the way I do. And that’s why you find things like this bike designed to exercise the whole body:
According to the inventor, “The object of the invention is to provide means whereby one may enjoy with a bicycle or similar vehicle exercise like that of rowing with a pair of sculls, which is adapted to develop the muscles of the arms and body as well as those of the legs.” That’s all well and good, but I am not super clear on how one gets it started, nor how one safely stops. Steering is apparently accomplished by raising or lowering the “oars”, which turns the front wheel.
In terms of balancing, I suppose it’s no different from a recumbent bike, where the rider’s feet are positioned out in front of them, but with a higher center of gravity.
This patent dates back to 1900, but there are more modern takes on the concept as well. For example, these people make a much simpler design, which seems less dangerous overall. They also own the trademark for “Rowbike,” so, you know, watch out.