GPS Phone apps and device like this. http://www.lifehacker.co.uk/2015/10/27/the-lancaster-gps-speedometer-lets-downhill-longboard-skateboarders-track-their-fas

GPS Phone apps and device like this. http://www.lifehacker.co.uk/2015/10/27/the-lancaster-gps-speedometer-lets-downhill-longboard-skateboarders-track-their-fastest-runs http://www.lifehacker.co.uk/2015/10/27/the-lancaster-gps-spe...