Understanding Bike Fit – Knee Alignment

As mentioned in common bike fit issues part 1, knee alignment is very important to a proper and efficient fit.  Poor knee alignment at best is inefficient and does not allow for good power transfer and at worst will cause injuries.  Correct knee alignment is effected by a number of factors, listed are the 3 most common I come across in the studio.

  1. Cleat position –  The location of the cleat on your shoe will affect your knee tracking.  Cleats have multiple positions: for, aft, side-to-side, rotation (toe in-out, heel in-out) and tilt.  Where your cleat is located on your shoe not only affects the comfort of your foot but also the alignment of the knee as it travels throughout the stroke.  Note: A worn or broken cleat will perform incorrectly and cause the symptoms of poor cleat alignment.
  2. Foot position – Where your foot sits in relation to your hip.  While many times the foot-hip position can be adjusted via the cleat position it is not always the possible, such as when the pedal spindles are too short or the crank width too wide. The hip-foot relationship can also be effected by your stance (distance between feet) on the bike  or the Q-factor (distance between cranks).   A significant discrepancy between the width of your hips and the spacing between your feet when engaged to the pedals will cause the knees to be poorly aligned throughout part or all of your pedal stroke.  Many times an athlete will feel their foot is pushing in or out on your shoe when the hip and foot are out of alignment
  3. Saddle Position – Saddle position directly affects knee tracking.  Having the saddle too low tends to force the knees and foot in at extension (bottom of stroke) and out at flexion (top of stroke), giving the visual impression of looping when looking at the knee from the front.  Saddle too high tends to have the opposite effect. 

 

  • Other factors – More common contributors to knee alignment: 
    • Pedal choice.  Pedals come in different spindle lengths, width of platform, support and float (ability of the cleat to rotate in the pedal).  Your pedals need to allow for proper foot position relative to your hip. 
    • Shoes.  Shoes need to be supportive and hold the foot in the right position, if they are worn out or incorrectly sized they can cause a misalignment of the cleat position.
    • Insoles.  Some athletes need different support within the shoe to keep the foot aligned.  having the wrong or a worn insole can allow the foot to become misaligned. 
    • Orthotics. Using orthotics made for a different sport will cause issues, it is very rare that orthotics made for running are correct for cycling.  If you need or choose to use custom orthotics it is best to have them specifically made for your cycling. 
    • Wedges. Wedges are used to account for Varus and Valgus foot tilting.  Wedges are a fantastic tool for solving fit issues, however they can also be a problem.  Over wedging is more common that under wedging, however both are a problem.  If the foot is over/ under wedged the cleat and/or whole foot will be misaligned and cause the knee tracking to be affected. In many cases this will cause pain and/ or discomfort and in extreme cases injury.
    • Shims.  Different than wedges a shim is designed to deal with leg length discrepancies (LLD).  LLD’s come in both functional and anatomic.  a functional LLD is generally not fixed by shims, however a true anatomic LLD is.  If not assessed properly placing shims for a functional LLD or the incorrect length for an anatomic LLD will cause issues at the hip that will translate to poor knee tracking. 
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