As you peek into the door of many indoor cycling classes, or if you've watched some of the many "Spinning®" classes on YouTube or on television, often you will see frantic legs pedaling so fast it's more like the roadrunner trying to escape Wile E. Coyote. Legs are blurring so fast you often cannot even see them.
However, many students in typical indoor cycling classes do not have the skills to pedal quickly with good form. As a result, they bounce all over the place. It's wasted energy that isn't channeled into a productive output of power.
But, these students may be whooping it up along with the instructor and believe that they are working hard. I've seen instructors yelling at students to spin the legs faster and faster, sometimes in excess of 140 rpm. Heart rates are high and sweat is flying, so the perception is that they are doing a lot of work. This unfortunately is the image of far too many indoor cycling classes.
If I could have a moment with these instructors and their students, I could prove to them that they really are not working as hard as they think they are, and therefore, they are not getting the benefits they imagine they are. Benefits such as aerobic development, muscular endurance, muscular strength, leg speed improvement, or even threshold or anaerobic benefits. The majority of them would achieve more and improve much more quickly if they would just slow down the legs and turn up the resistance knob.
Why We Pedal So Fast
One of the reasons for the excessive cadences indoors is the mechanics of an indoor bike. It's easy to pedal fast indoors! Most typical indoor cycling bikes are fixed-gear systems with weighted flywheels. The flywheels can be as heavy as 45 pounds and are often weighted on the circumference. This gives them inertia, and is responsible for the smooth feel as you pedal.
While there are benefits to this, there are also implications on how fast you can, or should pedal, and whether or not that fast pedaling will improve your neuromuscular abilities and translate to faster cadences outdoors. As a cyclist, you have probably noticed that you can maintain a much higher cadence indoors than you can on your outdoor bike. The reason is because of that weighted flywheel. In reality, it is cheating!