1. Lift your arm so your forearm stays relaxed and horizontal.
2. Locate the thickest point of your forearm.
3. Wrap a measuring tape or a piece of string around this point. Do not over-tighten.
4. Mark the point where the tape or string overlaps.
5. Lay the string flat against a ruler to read your exact measurement.

1. Stand upright with your back and shoulders flat against a wall.
2. Bend your arm to a 90-degree angle and make a fist.
3. Hold a pencil in your hand and make sure it's kept perfectly vertical.
4. Measure the horizontal distance from the wall to the tip of the pencil.
5. For the most accurate result, ask a second person to help take the measurement.

1. Stand barefoot with your heels, back, shoulders and head against a wall, looking straight ahead with your chin tucked in.
2. Carefully place a book on your head and slowly push it against the wall so it’s parallel to the floor.
3. Measure from the bottom of the book to the floor — this is your height.

1. Wear cycling bibs, tights or slim fit underwear and stand barefoot with your back against a wall.
2. Tuck a book between your legs and pull it up into your crotch to where your saddle would be.
3. From the top edge of the book to the floor is your inner leg length.

Choose between low, balanced and comfort.

Lower aero positions demand greater flexibility and are harder to sustain over longer distances.

Choose between compact and stretched.

Compact is best for most athletes. A stretched position maximises aero, but requires greater core stability.