Tech Q&A: What Does It Mean For A Pedal To Have Float?
Q: I am considering changing the pedals on my bike. I am currently using Speedplay pedals with a stainless steel spindle, and I have two questions. First, would switching to a pedal with a titanium spindle be beneficial? Second, I’ve been told that my pedals have too much float. What is float, and how do I determine the right amount of float for me? Question submitted by Frank Blazic of Cayucos, Calif.
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Christopher Kautz answers the question: What does it mean for a pedal to have float?
Q: I am considering changing the pedals on my bike. I am currently using Speedplay pedals with a stainless steel spindle, and I have two questions. First, would switching to a pedal with a titanium spindle be beneficial? Second, I’ve been told that my pedals have too much float. What is float, and how do I determine the right amount of float for me?
Question submitted by Frank Blazic of Cayucos, Calif.
A: Pedals with titanium spindles will be slightly lighter than pedals with stainless steel axles. This is because titanium is less dense than steel and is therefore lighter per unit volume. However, titanium is also not as strong, stiff or as hard as steel per unit volume. Given that the shape of the pedal axle is not going to change much between a steel axle and a titanium one because of mechanical constraints, there will not be any material added to increase the strength of the titanium axle through increased volume. As a result, you will have a pedal system with weaker and more flexible axles. You can see attempts to deal with this on a Look Keo pedal, for example. The steel versions use 8mm Allen keys to install them, and the titanium version uses a 6mm key, allowing Look to remove less material from the titanium axle.
This reduced strength is why many pedals with titanium axles have rider weight limits on them. If you are a lightweight rider, this may not be of concern to you, but you will need to keep this in mind if you are a heavier rider. Furthermore, pedal systems in which the axle also serves as the bearing race can have longevity problems since the steel bearings will wear down the softer titanium axle. Pedals that have their bearing in a cartridge will not have this issue, but this is something to keep in mind when looking at pedals. Knowing all of this, it is doubtful that you would see any measurable increase in performance by switching to a pedal system with titanium axles in place of one with stainless steel axles. If your goal is to build the lightest bike possible, however, then titanium axles will help you accomplish that.
The Issue of Float
A floating pedal stands in contrast to a fixed pedal. Fixed pedals do not allow rotational movement of the foot once the cleat has engaged the pedal. Essentially, you are locked into place with a fixed pedal, much like a ski binding.
Early clipless pedal systems, such as the original Look pedals, were all fixed pedals. Fixed pedal systems require that the cleat be set up perfectly to match the natural movement of the foot of an athlete through the pedal stroke. If this is not done correctly, torsional forces are applied to the athlete’s leg, often causing discomfort and potential injury to the knee or hip.
A floating pedal system allows the foot to rotate more or less at the ball of the foot, right over the center of the pedal. Having float means that the rotational adjustment of the cleat is easier, since the athlete can rotate the foot into its natural position while pedaling. Float also allows for an athlete’s foot to rotate throughout the pedal stroke, which benefits most athletes because very few people are stable enough biomechanically to ride a fixed pedal system efficiently.
The amount of float that a pedal has varies between pedal systems. Most floating pedal systems will range from about five to 15 degrees. Some pedals, including the Speedplay Zero and Look pedals, allow you to adjust how many degrees of float you have as well as direction or directions in which the float occurs. Speedplay also makes the X series of pedals, which has 30 degrees of float but is not adjustable.
Having the proper amount of float is beneficial because it provides a degree of stability that having too much float does not. Float, while helpful for the reasons listed above, is a mixed blessing. Too much float does not provide a mechanically stable platform for the athlete to drive from, forcing the athlete to provide the stability. Many athletes do not have this ability. In such a case, the pedal system allows the athlete to fall into his or her biomechanical imbalances and further reinforce them. This can be particularly problematic for newer athletes or those with more pronounced biomechanical problems.
A pedal with limited float, when set up properly, allows an athlete enough movement to ride comfortably and without injury while also providing a degree of stability to help prevent unwanted movement. It is best when setting up such a pedal system to seek out a professional bike fitter that has been trained to understand the complexity of the biomechanics behind making the necessary adjustments to the system in order to get the most benefit from it.
Christopher Kautz, MA, is the owner and founder of PK Cycling and one of the originators of the fit studio concept. His clients include numerous Ironman world champions, Tour de France veterans and Olympians. You can find him online at Pkcycling.com.