There are many scenarios that can lead to knee pain in cycling, but the most frequent causes are: improper saddle height, improper saddle fore and aft position, shoe and pedal interface problems, leg length discrepancies, and over-training. Because of the unique nature of cycling, riders should obtain a proper bike fit to avoid injury. Cyclists pedal in a relatively fixed position over a long duration. In a four-hour ride, a cyclist pedaling at an average of 90 rpm will complete roughly 21,600 pedal revolutions.
Improper Saddle Height
A saddle height that is either too low or too high can lead to overuse injuries. A saddle height that is set too high can lead to posterior knee pain due to the over-extension that occurs as the pedal reaches the "dead" spot at the bottom of the pedal stroke. A saddle height that is too low can lead to anterior knee pain (most commonly patellar tendonitis). A low saddle height will increase torque at the knee as it comes through the top of the pedal stroke. The saddle height should be set between a 25- and 35-degree knee angle, with the pedal in the six o'clock position, for both injury prevention and optimal performance.
Saddle Fore and Aft Position
A saddle that is adjusted too far forward can apply excessive stress leading to anterior knee pain, while a saddle that is set too far aft can lead to posterior knee pain. Saddle fore and aft position should be adjusted so that the tibial tuberosity is centered over the pedal axle when the pedal is positioned in the three o'clock position. This setting will allow for optimal power transfer while decreasing stress on the knee.
Shoe and Pedal Interface
Cycling shoes and pedals are designed so that the cyclist can pedal more effectively. Pedal float refers to how for the cleat can rotate prior to disengaging form the pedal. Too little float prevents the natural movement of the lower leg during the pedal cycle, which may add undue stress to the knee, leading to knee pain. However, too much float requires more stabilization at the knee joint and can lead to an overuse injury. Utilization of 6 to 9 degrees of float is recommended for most individuals.
Crank Arm Length
Crank arms that are too long for the cyclist's leg length can place added stress on the knee as the pedal is transitioning through the top of the stroke. Increased knee flexion through the top of the pedal stroke can lead to chronic anterior knee pain. Crank arm length should be adjusted based on the rider's leg length.
Increasing training volume or intensity too quickly is a common mistake made by riders of all levels. Increases in training volume and intensity can lead to anterior knee pain. Slowly increase training intensity and volume in order to avoid developing an overuse injury.