I have used this electronic odometer only once, and after I put all the info into the device (26 inches each wheel) it said that I had ridden my bike (a 26 inch hybrid) for almost 11-1/2 miles. So my unit is VERY inaccurate, since I googled the distance and it added to only a little more than 8 miles - 33 percent less. Other thoughts: As I started to put the computer on my bike I saw that the mounting "hardware" consists of only several plastic zip ties, as though the manufacturer even concedes that it won't last way too long (or perhaps that the user will upgrade to something better?). Everything else that I have placed on my bike has mounting hardware that's much more permanent instead of these small white zip ties.