The S-shape of the spine must also be maintained in forward-leaning sitting positions in order to ensure a relaxed and back-friendly riding posture.

Above the pelvis, in the area of the lumbar spine, the back is curved inward, forming the lumbar lordosis (“small of the back”). Without this natural lumbar curve the spine cannot retain its S-shape. The lumbar lordosis makes it possible for the back muscles to hold the upper torso in a forward-leaning position without support from the hands. The degree of incline for the upper body is highly dependent on the strength of these back muscles.

For weaker muscles it is advisable to choose a higher handlebar position, up to 15 cm (6”) above the height of the seat. Riders with stronger (better toned) back muscles can choose a lower handlebar position. (Fig. 5: 1.= All-round , 2.= Dynamic, 3.= Sporty Position)

The extended back posture can only be maintained if the hands are placed in the correct position on the handlebars. In a posture with an extended (S-shaped) back it is important that the upper arms are positioned perpendicular to the upper torso. The upper arms, together with the shoulder muscles, can only provide sufficient support if they are positioned perpendicular to the upper body. (Fig. 6)

If this angle is too small because the seat is too close to the handlebars (Fig. 7a) then the body will try to create this angle by rounding the shoulders (Fig. 7b). A good comparison would be trying to do push-ups with your arms positioned too low. This is extremely strenuous, and the body tries to compensate by hunching the shoulders.

When the shoulders are pushed towards the back the neck is over-extended, the arms are straightened and the lumbar lordosis is flattened. The back muscles can no longer support the upper body, and the weight must be supported by the arms and hands.