About The Wedge and Cycling Biomechanics

Knee Pain & Pedal Alignment

Knee pain is the number one injury among cyclists of all levels, often the result of improper pedaling mechanics carried out over thousands of miles in the saddle. The primary factor influencing knee movement and possible tissue strain is the fit between cyclist and bicycle. One of the most important points effecting alignment of the knee during the pedaling cycle, is the connection of the foot with the pedal. A research study published in the Journal of Orthopaedic and Sports Physical Therapy reported that 87% of the population has a misalignment in their foot structure known as "Forefoot Varus." This is where the foot tilts up to the inside position (Figure 1). In this same study, it was found that an additional 9% of the population have another misalignment known as "Forefoot Valgus." This is where the foot tilts to the outside when the ankle joint is in its neutral position (Figure 2)*.

Conventional pedal systems are designed for the cyclist to clip in flat-footed. This is ideal for those rare 4% of cyclists without a forefoot tilt. For all others the most common result of this faulty foot position is a side to side motion of the knee during the pedal cycle. This occurs due to a chain reaction of joint movements in the leg. In the case of Forefoot Varus the tilted foot presses down flat on the pedal causing the lower leg to rotate inward toward the bicycle frame. In turn the thigh moves in toward the frame to decrease stress at the knee. These movement result in the knee moving out of its desirable, straight up and down motion and the inward motion of the knee causes the kneecap to get pulled out of its normal path, thus resulting in pain under the kneecap (Figure 3).

Placing a wedge at the foot/pedal interface will decrease side to side knee motion reducing the potential for repetitive knee trauma.

LeWedge was developed to correct this common misalignment. LeWedges are non-compressible plastic shims that cant the foot's alignment back to its natural position. The wedges are totally symmetrical, so they can be used to cant the alignment in or out, or correct for leg-length discrepancies by reverse stacking methods that do not alter the cleat's position on the shoe (Figure 4).

Note: There are in fact many factors that may cause knee pain such as proper seat height and fore/aft position. If a persistent knee pain continues the cyclist should seek professional medical advice.

* Garbalosa JC, McClure MH, Catlin PA, Wooden MJ. "The frontal plane relationship of the forefoot to the rearfoot in a asymptomatic population." Journal of Orthopaedic and Sports Physical Therapy. 1994;20:200-206