The standard technique is to do a roll-out, where you measure how far your bike goes (when sitting on it) with one revolution of the wheel. This will vary with your weight and tire pressure. An alternative is to compare the computer readout with a known measured course of at least 10 miles. Examples would be using road mile markers. Then you can correct for the difference. For me, a 23 mm tire rolls out to 2095 mm.tyson8earzz said:IUnder Settings > Bike Profile, i see the option to insert the wheel size but currently it is on AUTO. But under that it says 2174mm. If i have a 700x23c mounted tires and standard size road bike wheels, what is the proper milimeter size supposed to be? How can I make sure the 2174mm is correct?