Another factor to consider is that walking that much faster than average traffic is difficult in dense place. While I don't have a measurement, I typically walk

Another factor to consider is that walking that much faster than average traffic is difficult in dense place. While I don't have a measurement, I typically walk ~twice as fast as the average speed on the street. I once was walking in a very crowded bridge in Hong Kong, and the "friction" I can from the surrounding traffic is tremendous, not to mention you need to be very agile in these situations to not get any trouble. Also, I wonder if anyone really need this tool to walk 2.5x faster. May be because I have long legs, but I found that open up the legs (the angle of the swinging motion) and increasing frequency can already speed up a lot without being too tiring (bigger angle is easier than higher frequency.)