You have to drive a few blocks. The monitor on this particular model is always on - it lights up if you bump the bike or move it even when you are stopped. When stopped, it displays the last data it had stored before the bike stopped. The sensors are based on the tire revolution so the data refreshes once you get going again (probably a quarter mile or so).One question. Does the monitor display the tire pressure on start up or do you have to drive a few blocks for the monitor to show the pressure?