Stand the bike upright on level ground
Measure from the center of the bottom bracket to the top of the seat tube
Use a tape measure for the frame size
Measure in centimeters for road bikes and many hybrid bikes
Measure in inches for mountain bikes and some older bikes
Check the manufacturer’s size chart for the exact frame size
Measure the top tube length if you need a fit comparison
Measure the standover height from the ground to the top tube
Compare the measurements with your inseam and riding style
Verify whether the frame uses center-to-center or center-to-top measurement
Record the frame size and compare it with standard bike size charts