The Truth About Indoor Cycling Cadence

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 pedal 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!

If your club has these kinds of bikes with the weighted flywheels, here is a test you can do that will highlight this point (Startrac Spinners or Schwinn bicycles older than a year or two are two common manufacturers of these bikes, though your club may have another brand with similar characteristics):

Stand next to the bike and turn the resistance knob all the way to the left so there is no resistance. Now grab the pedal and turn it very quickly for about seven or eight good solid turns until the pedals and flywheel are spinning at well over 100 rpm (use caution that you don't get your finger caught in the pedal axel and stay out of the way of the moving pedal because if it hits you it will not stop). Now wait. You will see that it will take a long time, a very log time, before it slows down! This is because of the inertia in the weighted flywheel—it assists in the momentum of the drivetrain.

Because of this, all those unskilled riders pedaling at high cadences with no or insufficient resistance, bouncing all over the saddle, are basically strapped on to those pedals for the ride. They don't have to do much work to keep them spinning at high cadences when the brake is not touching the flywheel. In a way, they are being ridden by the bike, instead of riding the bike. Without resistance, they will not achieve some of the fantastic benefits that indoor cycling provides. Because their heart rates may still be high, they interpret it as "work" and believe the calories burned number their heart rate monitors give them.

Sadly, this is not the case, and may very well be the reason why some people do not see the results they could be seeing in indoor cycling classes. It's important to remember that heart rate is not always an effective indicator of how much work you are doing. Power measurement is much better. I know that power meters are still not very prevalent in fitness clubs, but that is slowly and surely changing as more and more adopt bikes with measurement tools.

The answer to success lies in that resistance knob!

How it Translates Outdoors

There is proof, if only I had the opportunity to show it to these riders and instructors. If they had a power meter on the bike, they would see that pedaling at high cadences and very low or no resistance actually produces a low power output. Heart rates are high because of the lack of technique, the bouncing and flopping in the saddle and the general inability to contract their muscles quickly.

Poor technique is costly in terms of calories, yet those calories don't translate to strength, fitness, muscular endurance or aerobic endurance benefits. It would be much better to channel the effort into a higher power output by raising the resistance and slowing the legs down. As mentioned earlier, power translates directly into calories burned; heart rate is only an indirect (and often incorrect) indication of how many calories are burned in an exercise session.

The next litmus test would be to put them on a road or mountain bike and ask them to pedal at 120-140 rpm and sustain it. Very few people, except the most skilled cyclists, could do that for very long outdoors, although it's somewhat easy to maintain indoors when there's no resistance. In order to do this on a flat road, most would have to be in a granny gear. Pedaling at 120-plus rpm in that granny gear, their speed would be so slow that a child on a tricycle could probably pass them.

Again, their heart rates would likely be high, but the lack of speed would be blatant proof that they are doing very little actual "work". Outdoors, when your feet are flailing but you aren't moving forward quickly, it's a sign that you need to increase the gear. When you do, your cadence will slow down to (most likely) less than 100 rpm but you will go faster. This means your power output is higher. Indoors, we don't have the benefit of forward movement—or lack of it, to show the rider that excessive cadences and no resistance translate to little actual work.

So...How Fast Should You Pedal Indoors?

I haven't given a range of "acceptable" cadences in an indoor cycling class because the answer is "it depends". It depends on the skills and fitness of the rider and how much time is spent practicing. Just letting the legs spin fast out of control as happens in so many classes does not amount to practice. It is a waste of time. This is an excellent example of the adage "practice doesn't make perfect, only perfect practice makes perfect." You must perfect your technique first, then work on leg speed.

For the general population, I use an upper limit of 100 rpm for most indoor riders. I have many students in my classes who are challenged at cadences over 90 rpm, but that is because I'm a stickler for form, don't allow any bouncing, and always make sure they have some resistance on the bike. This is much more similar to being in an outdoor situation.

If you are a cyclist who already has a smooth pedal stroke and who is used to pedaling at 100 rpm or more outside, you certainly can do so indoors. Simply make sure that you are in control of the drive-train at all times and that you always have some resistance.

You will know when you are being pulled around by the flywheel—there is a sense of being pulled along, as if by a zealous dog on a leash. To avoid this, work on technique by spinning circles. Try to minimize the focus on the downward phase of the pedal stroke. You are already very good at the part—you did it on your tricycles! Focus more on the bottom and top halves of the pedal stroke. The more you relax the upper body and the hips, while sitting deeper in the saddle, the easier it is for the leg muscles to contract quickly. By learning to "spin" instead of "mash" on a bike with a flywheel, you will be less susceptible to being "ridden by the bike".

Check yourself in the mirror if there is one. You can see if you are bouncing. If there are no mirrors, have someone observe you from behind; it's more evident looking from the back. Once you start bouncing, you have exceeded your cadence "threshold". Back it down, and raise the resistance just a little until you find that right combination of resistance, at a cadence that is just beyond your comfort zone. For best results, do this without exceeding your anaerobic threshold; in other words, while staying aerobic and in control of your breath.

These tips are how you can improve your leg speed indoors and make sure that it translates to your cadence outdoors. If you do not commit this much time and focus indoors, then you will not likely find that your high-cadence pedaling in your standard, unaware, excessive-cadence indoor cycling classes has done you much good during the offseason.

Here's to riding faster!