I've spent a good deal of words talking about saddles and aerobars, which together constitute two of the three contact points on a tri bike. Today I'm going to talk quite a bit more about contact point number three, the pedals. Technically, we can include shoes in this third category, and indeed, shoes are a critical piece of this puzzle. Nevertheless, pedals constitute an important element in the fit equation, and deserve a closer look than they traditionally get.
This article is meant as a bird's-eye view of available pedal technology. It's a broad survey of what's on offer in the market today, and the general strengths and weanesses of each option. The four pedals we're going to look at are Shimano's Dura-Ace Carbon, Speedplay Zero, Keywin, and Aerolite.
The Shimano pedals in particular carry a bigger burden than the other entries in the article. This is because they are here to represent a much broader cross-section of the market. The mechanism they use, a derivative of a ski boot binding, is perhaps the most popular and prolific design in modern road pedal history. Brands currently producing this type of pedal include LOOK, Time, Mavic, Exustar, Expedo, Shimano, and others. These pedals have more similarities than differences, and I didn't want to waste any time comparing them to each other. Instead, Shimano stands as a proxy for the entire ski binding crowd, and in my opinion, is an excellent candidate for the job.
As a side note, if you want to explore historical pedal design, I highly recommend a visit to Speedplay's Pedal Museum.
Thus, every pedal in this review is categorically distinct. I picked these four because of what they represent for the market as it stands today. Each one approaches pedal philosophy in a different way. Should float be free, or restricted? How should it be controlled? How should one prioritize the various metrics of stack height, weight, price, etc? Why use the particular mechanism that was chosen? These are questions that each manufacturer answers in their own way, and their products will therefore appeal to a different set of riders. We will explore those questions and answers in detail. But as usual, we're going to preface our discussion with a look at something that will inform the discussion. In this case, we'll look at couple key tenets of pedal fit.
Stack and Stance
There are exactly two ways in which pedals alter your fit. One is by the overall stack they contribute - this is measured as the distance between the center of the pedal axle and the bottom of your shoe sole. It also has implications for power transfer (lower is better), but for the moment, let's set that aside. As a fit metric, it can easily be factored out. If pedal X and pedal Y differ in stack by 5mm, all you need to do is raise your cockpit and saddle by 5mm, and your fit is the same. Your pedaling circle doesn't actually change at all.
But by far, the more important fit consideration among pedals is their stance width. This is sometimes referred to as Q-Factor, although that term is more often used to describe the outside distance between crank faces. The folks at Speedplay take issue with the use of the term for pedals. They'd rather you use the term "tread" to refer to pedal stance. But personally, I actually prefer to see Q-terminology used for both crank and pedals, since both components contribute to a single measurement: the stance width of your shoes while pedaling. It just makes more sense to me that way. I like to think of Q-Factor as follows:
Crankset Q-Factor: the distance between the two planes that run through the outer face of each crank arm's pedal insert. Or more succinctly, crankset stance. The reason for the longer definition is that many cranks have a recessed pedal insert, so measuring to the outer crank face would overstate the measurement.
Pedal Q-Factor: the length of one pedal, measured to the center of the pedal body.
Overall Q-Factor: Crankset Q + Left Pedal Q + Right Pedal Q
I may use the term Q-Factor interchangeably with stance width to describe any of these three measurements, and it should be clear from the context which one I mean. So if you see me conflating those terms, it's not done out of ignorance; it's a conscious choice that I think makes sense.
But why is pedal stance important? It can have serious biomechanical implications for a rider, contribute to or resolve knee pain, improve pedaling efficiency, and more. I recently attended the bike fit of a high-profile triathlete, and the athete's right knee was tracking terribly with his existing cleats. The fitter correctly identified the issue, and got the athlete on basically the narrowest cranks and narrowest pedals on the market, and voila! The result was a near-perfect knee track during the pedal stroke, as measured by a 3D capture camera.
It's an important thing to keep in mind, but we won't focus much on it in the components of this review. Just remember that if you have a particular fit need that involving stance width, you may be constricted in your pedal choice, because some pedals come in only one width. Others, especially Speedplay and Keywin, were built on the philosophy that width adjustment is critical, and offer replacement spindles to help you make those adjustments. Other pedals allow some stance adjustment at the cleat, but this can be limiting as well. For example, Shimano's cleats let you move plus or minus about 2.5mm from center. That's nice, but if you needed to max it out, then you'd be unable to rotate the cleat as well. You'd have to effectively lose just a little bit of that 2.5mm of stance adjustment in order to rotate the cleat.
It's also possible to control Q-factor at the crank, rather than the pedal. But sometimes a narrower crank isn't available, or it isn't enough to satisfy a fit requirement. It's always better to have more routes to achieve your fit, which is why I'm a proponent of pedal Q adjustment.
So with that out of the way, let's get started. As mentioned, we're going to look at four very different pedal styles. As usual, I think it's good that there are such a wide variety of options available to consumers, each of whom will have their own priorities in terms of what they want and what they're willing to give up to get it. People often ask me what the "best" option is. And although my answer may seem evasive, I truly believe that the answer can differ for each person. So instead of trying to tell the reader what to do, I instead try to illuminate what I believe are the important facts about each product, so that the reader can make their own informed judgment. And now, without further ado, we'll start with the pedal that's perhaps the most popular one on the market, Shimano's SPD-SL. The version we got is the top-end Dura-Ace Carbon.