Pedals and Biomechanics

A version of this article was originally
published in Triathlete Magazine

What are the advantages/disadvantages between the ‘Look’ style pedal vs. the step down Speedplay pedals? I was advised that the ‘lollipop’ style are better for my knees and provide better overall performance.

Thanx for your time,

Nevin J. Mann
Holmdel, New Jersey

Dear Nevin,

Because there are so many options within brands and price points, choosing an effective pedal system should be based more in how a certain model addresses your individual needs, rather than the initial design that the brand is best known for. Some of the important variables for triathletes to keep in mind when considering pedals, and how some of the more popular designs (Speedplay X and Zero, Look models, Time Impact and the new Shimano 7750 SPD-SL) address them, are outlined below.

Float: Knee pain is caused by too much float as often as it is caused by a lack of float. The amount of float that is best for you should be addressed in much the same way as a running shoe should be chosen. Just as there are different running shoe constructions (stability, neutral and motion control) for different levels of foot and knee stability, certain pedal designs work best for the dynamics of certain feet.

The more float a pedal has, the less ability it has to stabilize a mobile foot and knee under load. For riders with relatively stable (neutral) feet, this is not a big concern as they do not need to rely on their pedals to stabilize them. These riders can often use anything from the almost unlimited float Speedplay X series, to a properly adjusted fixed cleat pedal. If you have a mobile foot that collapses under weight (pronates or supinates), a pedal that has moderate or adjustable float of 15 degrees or less (6˚ or under if you are highly mobile), and properly adjusted cleats can offer your feet the stability they need to not strain the knee. Speedplay’s Zero models and Look’s A5.1 and CX-6 models offer adjustable float, while Look’s less expensive models come with a 15˚ float cleat and the option to purchase a black fixed cleat. Shimano’s new 7750 pedal comes with a 6˚ float cleat from the factory and the option to buy a fixed cleat. Time’s Impact system is unique because it offers 2.5-5mm of side-to-side (lateral) float while also having 5˚ of adjustable stiffness “angular float”. “Angular float” is designed to allow the pedal to give vertically if the rider’s natural biomechanics do not provide a perfectly linear force from the knee to the pedal.

Stance Adjustability: The 2nd metatarsal heads (second toes) are considered the balance point of your feet. Your pedals should be set at a width that aligns this point with your natural hip width/stance for optimal power and the least strain on the knee. A pedal’s cleat adjustment range and axle width both effect this. The Shimano 7750 and all Look and Speedplay pedals have a good amount of side-to-side cleat adjustment. Time’s Impact system does not use lateral cleat adjustment, but instead has a setting that accomplishes a similar thing by pushing where the foot sits on the pedal in by 2.5mm if needed. Axle/spindle width is handled differently by each manufacturer. Look’s CX line of pedals offer adjustable axle width to address a variety of shoe and body types, while Speedplay pedals have different axle widths depending upon the level pedal you buy. The least expensive Speedplay (X-3) has the widest axle in the line, while the titanium axle X-1 and Zero Ti are the narrowest. Shimano’s 7750 and Time Impacts are fairly low profile to begin with and do not have adjustable axles. If you have a narrow pelvis, you should look for a narrower spindle. If you have a wider pelvis, do not go with a pedal axle that is too narrow. Your shoe size and model will effect this as well.

Pedal Sole to Spindle: There is not much research that documents this as scientific fact, but the common claim has been that the closer to your pedal spindle your shoe sole is, the better your power, pedal stroke and stability will be. Time’s Impact pedals provides the closest pedal to sole relationship at 7.7mm. Speedplay are not much more at 8.5mm (when they are able to be mounted directly to a shoe), while Shimano’s new 7750 is 14.4mm and Look models are 22mm. The brand of your shoe effects this dimension as well.

Foot Numbness: Especially for distance athletes, small pedal to cleat interfaces can contribute to localized pressure on the ball of the foot that can lead to numbness. Larger cleats with a more spread out mounting pattern are better in this regard than cleats with a small bolt pattern. Two bolt (SPD-R and SPD mountain style) pedals are the smallest in this regard while 3 bolt cleats, like what Look, Time and Shimano’s 7750 use, are some of the largest. Speedplay’s cleat to shoe interface is not quite as large as the other options, but is more than adequate for all but the most severe problem cases in this aspect.

Canting and Shims: If you have a leg length discrepancy, or need cant shims to accommodate for twist in your forefoot, it is important to have a system that allows for this to be addressed as effectively as possible. Look’s top-of-the-line CX-7 offers canting adjustment that is integrated into the pedal’s body, while effective cant, shim and screw kits are readily available for all other Look, Shimano SPD-SL and Speedplay models. Smaller cleat designs (SPD mountain style) tend to be more challenging while specific cant and shim bolt kits for Time are not available yet.

Pedal Weight and Rider Weight: Rotational weight, like wheels and pedals, is of more significance than static weight, like a frame. When it comes to pedals, there are only a few ounces difference between the options. Comparing equivalent models between brands, Speedplay Zero Stainless and Shimano’s 7750 are some of the lightest pedals available at 330 grams for pedals, cleats and hardware. Time Impact Mag’s weigh 420 grams while Look’s CX-6 are 450 grams. More important than what a pedal weighs is how much rider weight and power it will hold. To guarantee durability, I do not often recommend titanium pedal spindles for riders over 150 lbs.

Convenience: All pedal systems have “secrets” that make them easier to get into and adapting to any of these system is not difficult. Two-sided designs, like Speedplay, are some of the easiest to get into as you do not need to think about which side of the pedal is facing up. However, most single-sided designs (Look, Time, Shimano SPD-SL) are counterbalanced so that the pedal hangs in a natural entry position too. When it comes to how dirt and mud effect the system, Speedplay’s Zero design and the other systems work reasonably well when dirty, while the Speedplay X series can be more prone to jamming. If ease of running in transition is a concern, the lowest profile cleat designs (Time Impact and Shimano 7750) are some of the easiest to run in.

Release/Retention: Especially for larger and/or more powerful riders, having enough retention so that you do not inadvertently pull out of a pedal under load can be an important consideration. Look’s higher end pedals offer a stiffer adjustment range than their more basic models. The Shimano 7750 uses a similar tension range to Look’s higher level pedals. Speedplay and Time pedals are designed to not need adjustable tension and the factory pre-set tension works fine for most riders. For Speedplay riders seeking additional retention, the Zero Track pedal is available with a spring that has about double the retention range of standard Speedplays.

Shoe Compatibility: Always double check and make sure that your shoes and pedals are compatible and be sure to get any adapter plates that are specific to your pedals and shoes for proper installation.

Regardless of what pedal system you choose, have a qualified professional adjust your cleats and analyze your feet and knees to see if you would benefit from the support of a custom cycling footbed and/or stabilizing cant wedges. From a power, comfort and safety perspective, this step is more effective in injury prevention and improving performance than any pedal system is able to be on its own.

Choose wisely!


Originally published April 2003/Copyright © 2003

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