Q & A Coach Forum – The Advantage of Float in a Pedal System
What is the advantage/disadvantage (purpose) of “float” in SPD-SL cleats?
Head Coach Scott Saifer responds:
Knees are designed to work beautifully for tens or even hundreds of thousands of miles of cycling provided that they are treated with respect. There are several concave and convex surfaces within the knee that need to line up just so to prevent irritation during pedaling. If the foot is stuck to the pedal in such a way that the knee is twisted, the internal parts of knee don’t line up properly. Instead of flexing smoothly, the parts rub on each other and cause the knees to become sore or even, after a long time, to wear out.
In the old days, cleats kept the foot stuck to the pedal at a precise angle. Some of those cleats were actually nailed to the shoe so if the alignment wasn’t right, correcting it was a nightmare. Most modern cleats have some built in free rotation in the horizontal plane or “float”. The cleats don’t have to be aligned precisely on the shoe, so long as the angle that makes your knees happy is within the range allowed by the float. Most riders will have their foot-pedal contact at the same angle throughout the pedal stroke so that a fixed cleat would work fine, if it were precisely aligned, while a few actually make use of the float during each pedal stroke.
Some pedals come with the option to use fixed cleats to eliminate the float. Most riders do well with float. I’ve heard that a small fraction may actually need a fixed cleat because they actually benefit by having some support against rotation but I haven’t run into any of these folks even after almost 20 years of doing fits. They must be rare.