I've had a Xootr Magnesium for years .. I use it all the time .. I also had a Strida .. stock on 16" wheels, you get around 48 g/i .. so to hit 15mph, you'd be approaching 100 rpm.. I ran the 355 wheel option on mine, that put the g/i around 55 and would let me reach 15mph at around 90 rpm .. one thing for sure, if the pavement, sidewalk, or street is not really smooth, the Xootr ride suffers compared to the Strida.. and the Strida is much easier on your body than a Xootr .. my Xootr trips are all around a mile or less .. of course now there is a 3 speed Strida, so more versatile gearing available, for a price...