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Coaches Panel: Suggestions for a rider with large leg-length discrepancy

  • By Paul Swift
  • Published Jun. 2, 2010
  • Updated Jan. 1, 2013 at 9:34 PM EDT
Paul Swift of BikeFit.com. Photo courtesy Paul Swift

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Large leg-length discrepancy

Dear Paul,
I have been reading your posts and I have a patient with a 3 centimeters’ length discrepancy due to a fractured hip. I don’t really see that having a long crank and a short crack is the answer; at the top of the pedal stroke it’s helpful, but at the bottom of the stroke it makes it twice as bad. I’m inquiring as to the amount of build up that can be achieved using cleat wedges (alternately stacked to create a platform).

— Larry

Larry,
Thanks for the question. 3cm is fairly significant. I would consider several options and perhaps combine a few of them. Often we think of only building up under the cleat of the shorter leg and this is a good place to start. In this case, however, focusing only on the one shoe is not going to be enough. With this type of situation, you can only build so far before the height of the shoe gets to a pivot point that makes it difficult to keep the foot stable — rocking too easily forward or backward creating undue stress.

I’d like to preface my answer by saying we must look beyond just wedges. To tell you just how many wedges to stack alternatively would be rather difficult. This answer depends quite a bit on the type of pedal and cleat the rider is using.

Here are a couple suggestions. Take a look at them and see which one(s) you can use. Most likely, your patient will require more than one approach to optimize his comfort and efficiency.

First, the type of pedal is important. You did not mention the brand of pedal your patient is using. So, I need to mention that the best approached will be with a cleat which requires 3 or 4 fasteners to secure the cleat to the shoe, such as Speedplay, Shimano SL or Look. A larger platform is best and the extra fasteners are important to keep this “build up” and cleat secure. Longer fasteners, which you will need, will be much easier to find for these 3 or 4-hole cleats than an SPD (2-hole) type cleat as well.

If you are working with a 2-hole cleat or SPD cleat, you may only be able to get one alternate stack of cleat wedges (single stack) to work well. You can use a Leg Length (LL) shim. But again, you might only get about 3mm of stack before losing good fastening security. The small area of contact provided with an SPD and being secured with just 2 fasteners makes it tough to get much build up.

Leg length shims (LL Shims) — Before considering cleat wedges I would consider a couple of leg length shims. Steve Hogg makes some in 3mm heights. We call them ”Hoggies.” You will need to stack up 2 or 3 of these to start. You may eventually consider more. But, we often start a little low and work up as opposed to potentially over stacking and then coming back down. Remember, the body has been compensating for this discrepancy for years. So, even a little build-up may be noticed.

Cleat wedges — Alternating two cleat wedges (a single stack) equals just over 1 mm in stack height. Use the cleat wedge to add 1mm or 2mm to the “Hoggies” you’re already using. This may be something you do right away on top of a couple LL shims or it may be a way to add a little more overall stack in-between sessions of adding another Hogg Shim. Often, cleat wedge stacking is used for the fine tuning of the “build up” you are creating.

You also might try a thicker insole in the shoe of the shorter leg. Cycling shoes are typically low volume but if you can get away with a millimeter in this fashion, take it.

Two different pedal systems — I was not able to double-check, but I think Shimano SL has a little lower stack height than the Shimano Ultegra SL. However, Look is taller than Shimano SL. So, you could use a Shimano pedal with the longer leg and a Look with the shorter leg. For even more difference you can use a Speedplay Zero on the longer leg and a Shimano SL or Look on the shorter leg. You can get up to 5mm of difference with different pedal systems alone. Here’s a chart to view some of the pedal stack heights.

Starting with Speedplay in the first place is something to consider when adding over a centimeter of height. Speedplay’s low pedal stack height keeps the amount of back and forth pivot (rock) lower than on any other system, adding more stability.

Different crank length may be considered. Not everyone I have tried this with has liked it. I suggest only a few millimeters difference to start. I’m not so sure I agree with your thoughts that it could be twice as bad at the bottom of the stroke as this is possibly where the most benefit may occur.

These are things you can try. However, if you want to take this to another level (and in this case you may not have any choice as all of these options may not be enough), there is one place and one guy that seems to have the tricks and magic to help with significant differences like this.

His name is Tom Slocum and the business is called High Sierra Cycle Center. It is not cheap. But, all of the work I have seen from him was excellent. We often refer to Tom when things are beyond our limits. Some items he sells you can find elsewhere at better prices like wedges (cants) and pedal extenders. However, when it comes to the real magic like “drop pedals,” there is nothing like it and any price would be worth it. Here’s a link for “drop pedals” and the High Sierra Cycle Center.

Hope this helps and many happy pedals to your patient.

— Paul Swift

An eight-time elite national champion and founder of BikeFit.com, Paul developed the Bicycle Fitting System (BFS), which includes products like the cleat wedges. The BFS helped bring the “front view” of a cyclist into the bike fitting world. BikeFit.com offers tools and education for bike fitters worldwide, helping them to better position humans on bicycles.

Any information or advice offered by the members of the Coaches’ Panel should not in any way be viewed as personal medical advice. The recommendations made in this column are offered as general information for healthy, physically fit amateur and professional athletes. None of the information provided by members of the Coaches’ Panel should be viewed as a replacement for personalized, professional medical treatment or to replace the advice or services of your physician. While some members of the Coaches’ Panel are Licensed Medical Doctors, Licensed healthcare professionals, and certified coaches, their advice in no way establishes a doctor-patient relationship between the writer and readers of this column. If you are beginning or resuming a vigorous exercise program, it is important to visit your health care provider for a complete physical examination in order to identify and treat any potential risks you might face.

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