One of the most famous debates in cycling and triathlon is the position of the saddle nose angle. The new UCI rule 1.3.014 simply states the saddle support shall be horizontal. Now with that being said we will examine all three saddle nose angles in a negative, positive, and neutral position.
If your saddle is in a negative angle or tilted downward your hips will slide forward causing an accordion affect on the knee which may lead to injury. The constant sliding forward while applying force to the pedals can lead to knee pain. Other issues with this saddle position are the tendency to ride on the narrower front part of the saddle which gives too little support, but also because the arms, wrists and hands are subjected to too much pressure as a result of the cyclist trying to maintain a normal position on the saddle.
Just the opposite having a positive tilt or tilted upwards has shown to cause the cyclist to be inclined and tilt his/her pelvis backwards (posterior tilt) which results in lumbar pain and can lead to numbness in the groin area. This can also lead to overreaching on the handlebars which can lead to shoulder and neck pain.
A. Neutral pelvic, B. Posterior Pelvic Tilt, C Anterior Pelvic Tilt
The saddle should be in a neutral position (0 degrees). The reason for this is it allows you to keep your pelvic in a neutral position. By keeping the saddle at a neutral angle and keeping the knee aligned with the pedal shaft you can optimize your performance being more efficient at utilizing the quadriceps, gluteus maximus, gluteus medius, soleus, gastrocnemius, and hamstrings muscles. Your hips will be in a more stable environment allowing you to apply force to the pedals pain free.
Note: When changing to a new saddle on the bike there might be a difference in saddle height. The height of the saddle plays an important role in comfort. If the saddle is placed too high, the cyclist runs the risk of posterior knee pain; if the saddle is placed too low, however, the pressure on his quadriceps might become disproportionately high which leads to anterior knee pain.
Piriformis Stretch Video Below