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Road Training

Coaches Panel: Length-length discrepancy

Paul Swift and Katrina Vogel answer a question about leg length discrepancy and the use of cleat shims.

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To the panel,

This is another leg length discrepancy related question. Here are some specifics:

I am a 54 year old male who began serious riding about 25 years ago.

When I was 13 I broke both bones in my right leg just above the ankle in a football game. This injury resulted in the right leg being 3/4 inches shorter than the left. Measurements have determined that the difference is in the lower leg, not the femur.

In the mid 80’s I made a shim of about 1/2 inch for the right shoe, which was placed under the cleat. When riding my right leg is much closer to the top tube than the left and at times I brush the top tube with it. I’m told that my left leg flops out at the top of the stroke and it looks like I’m toed in on the left as well.

My saddles have historically worn on the right inside of the nose. These problems have occurred even with the shim. I believe that the right side of my body over time has become stronger than my left. For sure my right leg is the stronger leg.

Generally I do not have discomfort when riding but when going hard over a period of time or after about 4 hours into a challenging ride the right side of my lower back can become very painful or my right lower abs begin to feel over worked.

In May of this year I bought a new bike and decided to have a professional fit and chose wobelenaught. The fitter said the system will work with my body restraints. He removed the shim I had used since the mid 80’s and set up the bike. The bottom line is that I do not feel that I am producing and even power delivery to the pedals, that I’m using my right leg and body more than my left. The left side of my crotch seems to bear more weight so I’m not flat on the saddle. I could go on and on.

I’m thinking I should just shim the right shoe and set up my bike like I have always done in the past. Then work on correcting my strength differences during off season on the trainer. Using a physical therapist is not possible for me right now as I’m unemployed. What do you think, should I shim as the starting point to correct this?

Many thanks,
D Mac
Charlotte, North Carolina

Paul Swift responds: (Katrina Vogel’s response is below)

D Mac,

Thanks for your e-mail.  We appreciate the detail as the more information we have the better. There are several things to consider. Upfront we will tell you our focus will be on the adjustments you can make to your shoes since working with a PT is not in the mix for now.

To begin, it sounds like you should put the leg length shim back in – now.

There are two adjustments to consider when the knee is closer to the top tube:

1.    Consider moving the foot in closer toward the crank. You do this by moving the cleat outward and away from the crank so the shoe moves closer. This may seem counter-intuitive. But, usually the goal is to get the foot under the knee.

2.    The other reason your knee comes inward is probably because you have a varus tilt at the forefoot. In other words the inside of your foot in its natural position is up higher on the inside. Kneel on a chair facing the back, let your feet hang off the front and have a friend look down at your feet. Have them look at the forefoot of each foot and see if the area just behind the big toe is flat across, tilted up to the inside or downward (your little toe tilts up to the outside). I suspect in your case the inner part of your foot tilts up toward the inside.

It appears you could use a couple of cleat wedges with the thick part placed under the inside of the cleat and the thin part under the outside of the cleat. I notice the Wobble Naught web site shows an old box of cleat wedges.  I do not know if they actually use them or if the box is on their site just for looks. It is common that knees coming in toward the top tube often mean your feet could use some wedges – thick part on the inside. 

As you describe the right leg being closer to the top tube, you also mention your saddle on the right side of the nose showing wear. This, sometimes, goes hand in hand with a tilt at the foot as your knee may divert inward bringing with it your thigh (next to the saddle). There is likely more going on with your hips which a good PT may be able to offer some help.  But for our purposes, we will stick with the adjustments you can easily make.

After removing the leg length shim, your left side at the saddle felt more pressure. This can happen due to your right side now having a longer reach.  This symptom makes sense and supports bringing back the shim.

On long rides you feel your lower back and sometimes right abs. I would see if the wedges in the right shoe help with this situation.  Start with two wedges (thick part under the inside of your right cleat).  You mentioned feeling uneven- Moving the cleat in and adding wedges may help you feel more even.

Now let’s chat about the left leg. Your knee flops out or moves away from the top tube at the top of the stroke. The location of the knee at the top of the pedal stroke helps guide us when setting side to side cleat positioning. I would try to move the cleat inward on this shoe to bring the foot out and away from the crank arm. Try to get the foot under the knee.

Most likely, the knee does not stay outward as it moves downward because it needs to follow the big toe. I suspect in this case you could also use a wedge (thick part on the inside) to bring the foot surface closer to your big toe. This way the big toe is not forced to reach as much when pushing downward. Combining the cleat movement outward and adding a wedge (thick part on the inside) will probably help to align this leg.

If moving the cleat in (to move the foot out) is not enough adjustment, you may consider a 1mm washer at the pedal spindle to move the pedal out a little. It does not sound like you need as much as a 20mm pedal spacer but maybe a 1/8” or ¼” longer pedal spindle could help.

Regarding the “toe in” you now have on the bike. When you sit, stand and or walk, does your foot point inward? If so, these adjustments may be on track. If your foot is pointed more straight ahead or pointed outward off of the bike, adjust your cleat to allow you foot on the bike to point in the same direction.

That is a lot to digest.  If you take your time, perhaps by trying one adjustment at a time you will get through it.

Paul Swift

Katrina Vogel responds:

Hi Donald,

I agree with you; put the shim back. A structural leg length difference MUST be corrected with some height added at the foot. There are other tricks that can be implemented as well but the general rule is to place 50% of the LLD height under your foot. Now, you have been riding for 25 years and using the shim since the mid’80’s and it is higher than 50% (LLD: 3/4 inch; shim: 1/2 inch). That is OK if it is working for you. (Question: Was the LLD measured with an x-ray in the 80’s or with a measuring tape? Were you standing up or laying down? If you were laying down and they used a measuring tape then I would recommend the following protocol.)

I recommend two things: 1) Verify the height of your LLD with a STANDING scanogram or a STANDING anterior-posterior pelvic x-ray. Those are the gold standards for determining the true amount of LLD. Measuring tapes allow too much human error. (5mm is considered an “acceptable amount of error” with measuring tapes. You need more specific information than that.) A scanogram measures the height of the foot, tibia & femur; the standing pelvic x-ray only catches the pelvis and upper femur. The goal is to measure the differences in height between the tops of the femoral heads to determine the amount of LLD. The standing x-ray is much cheaper (usually less than $100) than the scanogram and you will likely get a cash discount. You will need a doctor’s referral for an x-ray. 2) Have a friend or a professional fitter video tape you from the back as you try different heights of shimming for the shorter right leg. Watch the video and keep track of how you feel at the various heights of shimming. This will help you verify that you have the correct height.

Bottom Line: You are correct to keep the shim. Create the most stable base of support at the foot-pedal interface. Your legs are asymmetrical and, therefore, your foot-pedal set up will be as well. Do everything that you can to verify that you have the correct height. Put your bike back to where you were comfortable and make small changes as needed. You have been riding for 25 years and your body will likely do better with smaller changes over time instead of big changes all at once. It sounds like you may need to do some medial-lateral adjustments at the cleats (likely left foot out/right foot in) and potentially some varus cleat wedges to prevent the right leg coming in towards the top tube. All of these changes should help with the low back pain.

I am sure we could come up with more ideas but I think that is a good start for now.

Happy Pedals!


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kits pic
Katrina Z. Vogel

Katrina Z. Vogel was described as one of the “rock stars of cycling science” in VeloNews in 2007. She earned her Doctorate in Physical Therapy at USC and MS in Biomechanics/Human Movement & Performance at WWU. She is the Director of Education for Bike Fit Systems, teaches clinically-based bike fitting classes and guest lectures in Biomechanics for the Univ of Wash PT Department. She is a Cat 2 track cyclist.

Paul Swift
Paul Swift

A former 8-time National Elite Cycling Champion and founder of, 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. offers tools and education for bike fitters worldwide, helping them to better position humans on bicycles.

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