How a Bike Fit Breaks Down Your Pedal Mechanics

There are only three points of contact on a bicycle: the saddle, handlebars and of course the pedals. All three points are adjustable but the pedals are the most dynamic, and can be adjusted in five different parameters: fore/aft, rotation, medial/lateral, with wedges for foot biomechanics, and height for leg length discrepancies.

Getting all these adjustment correct can be complicated. It requires not only knowledge of equipment, but also the biomechanics of the human body. Most importantly, a proper fit process entails detailed communication and interaction between the cyclists and the fitter as to what feels the best. There is no automated fit process that can substitute experience or rider feedback and fitting is a dynamic process often taken in steps and stages.

Properly adjusted, the foot/pedal interface can prevent injury, increase power, and improve comfort; sometimes drastically. Yet, it is often the most overlooked or disregarded part of the fit process. Fitters and cyclists will often eyeball their cleat placement with little regard to proper placement.

But the adjustment process should include observation on the bike, analysis and measurement of biomechanics, installation, re-observation on the bike, and re-adjustment. This process in and of itself can take some time and even after the athlete has left the studio it may require slight adjustment after the cyclists puts some miles on the fit.

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Fore/Aft Adjustment

There are a great number of cycling shoe brands and models, each with their own engineering philosophy on how to make the "best" cycling shoe. There are about a half dozen popular brands of pedals with various cleat/pedal designs.

Starting with fore/aft adjustment we use the first and fifth metatarsal heads as our anatomical markers, or the two widest points of the forefoot. The center of the pedal spindle should be located between these two points with mechanical advantage of the plantar flexors towards the fifth (widest point at the outside of the forefoot). Many cleats have the center point of the cleat marked but some do not. I begin by marking the first and fifth metatarsal head on the shoe.

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Rotation/Float Adjustment

Float is the amount of movement in degrees that the cleat/pedal system allows. Float is often deemed "good" or "bad" but is in fact a necessary part of the pedal stroke, as the tibia must rotate.

By locking the foot in a position that it is not biomechanically designed for, force is transferred to the joints of the ankle, knee, and hips. This can cause injury.

I like to begin the process of adjusting for rotation by observing the athlete walking and standing to determine their neutral or natural position. It is not unusual to observe asymmetry when standing. We then try to match the neutral position on the bike. The less float in the pedal system the greater the accuracy the rotation adjustment must be. If the foot is up against the stopping point of the float when pedaling, it probably needs to be adjusted.

Varus/Valgus Adjustment

There are several ways to adjust for varus/valgus of the forefoot, all of which have the objective of creating a stable platform that transfers energy more evenly across the foot. These include under the cleat wedges, in the shoe wedges, or the use of tune able footbeds.

Each system has pluses and minuses and I like to assess the athlete before determining which system, or what combination of systems, to use. It is important to note that some shoes already have varus built into their design.

Although the vast majority of the population has some degree of varus (first metatarsal head is higher than the fifth), some cyclists do have a high stiff arch causing valgus. In this case a neutral shoe that does not have any varus built in is appropriate. By observing the client walking and by using a forefoot goniometer, we can determine the degree of varus/valgus and adjust/wedge accordingly.

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Stance Width

Unfortunately, stance width adjustment is more limited and some cyclists fall outside of the range of adjustment allowed by the cleat system; especially if they are larger individuals with wide hips. There are some things we can do with additional pedal spacers with these individuals. Speedplay does make a kit that allows a wide selection of pedal spindle lengths.

The goal of stance width adjustment is to get the foot, knee and hip aligned or to get the foot under the knee and reduce medial/lateral movement of the knee. This is the most leveraged position to produce power and along with varus/valgus adjustment can make significant increases in performance. Although "knees out" pedaling is never desirable, it is important to note that some cyclists cannot achieve perfect pedal alignment due to their biomechanical structure, injury, or both. Stance width alignment can be measured using a self-leveling laser.

Leg Length

Use the axiom "first do no harm" when adjusting for leg length discrepancies, which can be hard to diagnose. Leg length discrepancies are common and in most cases do not require adjustment; especially if under 5mm. It is important to diagnose a leg length discrepancy as functional or structural. Incorrectly adjusting for a leg length discrepancy can actually promote injury. Shims can be placed under the cleat, usually compensating for half the length of the structural discrepancy. Careful observation, especially of the hips from the rear is warranted, but the "gold standard" for diagnosis is a standing scanogram x-ray.

It is important to note that learning to properly fit for individual biomechanics and/or injury takes years of experience and training; and some clinical experience as well. There are more "automated" fit systems which are used as sales tools as well as fitting systems. These systems are designed for ease of use and training in a retail setting, and do not necessarily give a superior fit. Retail settings tend to have frequent employee turnover.

Make sure your fitter has the experience and training necessary to assist you, especially in the case of an overuse injury. If you are experiencing an injury the first step in the process should be a diagnosis and treatment from a doctor or therapist. Once the injury has been properly treated, schedule an appointment with an experienced and trained fitter to ensure the fit of your bike is not the root cause.

More: The Anatomy of Your Pedal Stroke

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