You’ll need a metal retractable tape measure and a book. In your socks, stand with heels and butt against the wall and your feet 8”/20cm apart. Measure from the floor to the top of your head. Now enter that measurement, in cms, in the left hand box. Do this for each measurement and at the end of the process. We’ll calculate the best frame size for you on the right.
Put on your cycling shorts and stand up straight on a hard, flat surface again in sock covered feet, with your feet 8"/20cm apart and your weight evenly distributed. Using your tape, measure a vertical line from the floor to the base of the middle of your crotch (pushing up a little to emulate the effect of a saddle). Ensure the tape is at a right angle to the floor and runs straight down.