Before any changes are made, your current set-up will be measured. E.g. seat height, saddle to bars, aerobars to the floor, etc. And then it should follow these three stages of measurement:
1. One foot is placed horizontal while the pedal is at the bottom dead centre and the upper body is in the aero position. Your leg can’t be dead straight behind the knee and your hips mustn’t roll over and downwards, so as to allow the foot to maintain flat. Aim: A solid riding style that allows the foot to push down without excessive toe pointing.
2. When pedalling in the aero position your knee should come within 4-7cm of the back of the elbow. Though some riders reach much further forward this can adversely affect handling, engage too much core muscle and prevent a low, safe head position. Aim: The upper arm to be between vertical and 10-20° off vertical. This keeps the elbow close enough to the shoulder to aid handling and comfort.
3. On the aerobars you should be able to look ahead without straining your neck. Ensure your saddle is at or very close to horizontal – you don’t want to fall onto the handlebars. Also check the forearm cups aren’t too low. Aim: Your torso silhouette to be slightly upward from the hip to upper chest area, this gives space for the knees to pedal without hitting the stomach and also helps digestion and breathing.