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).1
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.
1. 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

We have added the Lemond bicycle fitting system
to our specialty fitting service. We address better pedal performance and
increase comfort to the pedals. Consider greater power to the pedals at your
next event. If you are interested in the best, comprehensive bicycle fitting
program contact our staff.
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