Life from an outsider's perspective…

Human asymmetry & bicycle bio-ergonomics. Leg Length Discrepancies.

Lemond LeWedge

These days we have an infatuation with bike components when we should be more concerned about accurate bike fit. If you want the best peformance, you need the right-sized parts; you simply can’t win on a bike that’s the wrong size. But what if one side of your body is different to the other? If your body is not 100% symmetrical, then your bike shouldn’t be either…

One of the most common biological problems associated with cycling is a leg-length discrepancy. One symptom is an asymmetrical knee pain when cycling.

Frieberg1 has determined that about 50% of the population have uneven leg length, but found that of the low back pain patients, 75% had leg length inequality of 5mm or more. A leg-length discrepancy (LLD) can be diagnosed and accurately measured by either clinical examination, X-Ray, MRI or CT scans of the lower body. You may need to seek a specialist chiropractor or podiatrist who will refer you.

A number of causes can contribute to leg length discrepancy, including:

  • Any bone in the leg ever broken, particularly during growth years,
  • Congenital differences or uneven growth,
  • Disease-caused shortening of the muscles and connective tissue, a common after-effect of polio,
  • Surgically-induced differences, especially common after hip replacement surgery,
  • Compensation for problems elsewhere in the body, such as pelvic or spinal scoliosis.

If you have a leg-length discrepancy, don’t be afraid to FIX IT! You can remedy this common problem a by simply installing a shim under the cleat of the shorter leg.

Leg length discrepancies often cause asymmetric over/under pronation. You can determine if you pronate by simply looking at the wear patterns on the sole of your shoes. If the outside of the shoe is worn, you overpronate. On the other hand (foot!) if the inside of the shoe is worn, you underpronate (supinate). If your shoes wear evenly across the width of your shoes, consider yourself lucky!

If you know your feet overpronate or supinate, DO SOMETHING ABOUT IT! An interesting commerical solution is called LeWedge. Also consider installing different length crank arms if you have an extreme leg-length discrepancy.

Partly due to a leg length discrepancy, my left foot over-pronates to an extreme degree. The resulting ankle & leg pain is sometimes unbearable. I am not able to run more than about 2 or 3 km without considerable pain, yet I can cycle for 100+ km with no hint of a problem. Standing is also another problem. Although I am relatively fit on the bike, running a marathon is unthinkable.

For this condition, I require the use of a pair of very expensive custom-made orthotic devices, which help to a limited degree. Unfortunately, it is not possible to fit these inside my cycling shoes, so for many years I cycled with uncorrected feet. One day I decided to make my own wafered shims out thin sheets of wood from those cheap and nasty spanish banana packing crates, and my ankle and knee pains subsequently disappeared altogether. In fact, I was so accustomed to the constant ankle pain, I didn’t realise all the time when it was actually present!

It’s made so much difference that now whenever I use cycling shoes without the shims installed under the cleats, I can instantly feel the pressure on the outsides of my ankle bones (I can feel them grinding away). Since the success, I’ve also literally hacked off one side of the heels of my boots, forcing my feet into the proper positions. This too has provided instant relief when walking. Combined with the custom orthotics, this cheap solution has helped to alleviate my ankle pain to a great degree.

– Leslie

(1Friberg, Ora. “Clinical symptoms and biomechanics of lumbar spine and hip joint in leg length inequality” Spine 1983)

One Response to “Human asymmetry & bicycle bio-ergonomics. Leg Length Discrepancies.”

  1. hello my right leg is 25mm smaller than my left at the shin bone i broke my fib and tib bone about 18 years ago i started cycling about 3 years ago and have been srruggling to get comfortable icould do with some advice to even my legs onthe bike

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