Jump to:
- What is cycling power?
- Why does cycling power matter?
- What are the power-based cycling training zones?
- How do you set your cycling power zones?
- How do you test for FTP?
- How often should you retest your FTP to reset your zones?
- Should I pay attention to power or heart rate?
- How do you train using your power zones?
- Where in the zone should I be training?
- Do your power levels change when riding inside versus outside?
- The bottom line on cycling power zones: It’s an imperfect science
Cycling power, especially how it’s used for training, is one of the most misunderstood cycling metrics. First, you have to figure out your functional threshold power (FTP) through the help of a power meter and then use that information to set your training zones correctly. With that, you can effectively use your cycling training zones to tailor your rides to meet your goals.
To make cycling training zones a little easier to understand, we dig into the basics of power-based training, how to figure out your FTP, and tips on integrating power zones into training. We even provide a chart on power-based cycling training zones.
What is cycling power?
Very simply put, cycling power is the measure of work you’re doing on the bike. Cycling power is measured in watts, which is a standard unit of power (energy per unit time), the equivalent of one joule per second. But don’t worry, you don’t need to calculate that on your own. You just need a device that can read how much work you’re putting out as you pedal.
The measure of your power is the combination of the force you’re putting on the pedals (torque) and your cadence (rpm). This isn’t a calculation you can do in your head or by counting your pedal strokes though—you’ll need equipment.
Power meters are widely available now and come as hubs, pedals, and cranks. Smart trainers, like the Zwift Hub or Wahoo Kickr, and many indoor stationary bikes, like the Peloton Bike+, also measure power. Some apps, like Strava, even estimate your power if you don’t have a meter on your bike. However, to accurately train with power, you do need a power-measuring device and a cycling computer that’s reading information from the device during your ride.
Why does cycling power matter?
“From a physiological perspective, the power is what you are generating, and everything else—your feeling of exertion and your heart rate—are the effects of that effort,” Andrew R. Coggan, Ph.D., tells Bicycling.
Coggan is arguably the godfather of power-based training. His seven power levels are the ones most commonly used today, and his book, Training and Racing with a Power Meter, that he co-wrote with coach Hunter Allen, is still widely considered the seminal work on the topic. As a time trialist who loved crunching numbers, he saw the need to use power to objectively dial in his training and workouts in order to improve.
Unlike heart rate and rate of perceived exertion (RPE), power is external. It’s unchanging. A watt is a watt, and the watt doesn’t care if it’s hot outside and an effort feels harder as a result. It’s objective—sometimes painfully so—and it doesn’t care if you’re having a hard time on that climb, unlike a more subjective measure like perceived exertion.
“If you want to improve something, you have to measure it. There’s no better way of quantifying performance than measuring with power,” says Matt Wilpers, a cycling coach at Peloton. “Power is where rubber meets the road. Heart rate and RPE have a lot of noise in them. If you’re having a stressful day or you had too much coffee, your heart rate can go flying up, as can your rate of perceived exertion. We all live stressful lives, so having a data point that doesn’t include the noise that can come from those stressors is important if you want to see results.”
What are the power-based cycling training zones?
If you’re hoping to improve your cycling fitness, you’ll be doing workouts and rides that have specific designations, like a longer zone 2 endurance ride on the weekend, or an interval workout that focuses on improving zone 4, your threshold.
If you’ve trained with heart rate zones in the past, the names of these levels/zones should sound familiar. But rather than relying on your heart rate as the guide, you’re using power output to gauge the level you’re riding.
Still, as Coggan points out, the zones that you used for heart rate should roughly align with your power levels. You may notice some slight differences, but the idea is that your output (your power) matches how your body is reacting to that output (your heart rate).
Here, you can see how the zones should line up and how each should feel. Note that the percentages are based on your functional threshold power (FTP) and threshold-based heart rate, not your maximum heart rate or power.
If your FTP is 200 and your heart rate is 170 during that effort, 200 and 170 are your 100 percent power and heart rate, respectively. It can seem confusing at first, especially if you’ve never tested your FTP, but once you set your zones, it’s fairly simple. Read more on setting your zones below.
Your Cycling Training Zones
Last, a quick note: You can use the term levels or zones interchangeably, though Coggan prefers the term “levels.” But you’ll see it written both ways! Coggan likes to say levels because while these numbers seem strict, there is some nuance to it, and it allows for a more common-sense approach to following a power-based workout on an actual training ride.
“The notion of a zone is constraining,” he says. “You feel like you have to stay perfectly within this zone. But when you go out and ride a bike, you realize that power is so variable. It’s all over the place, especially if you’re riding outside. Coasting around a corner? Power drops to zero. Standing up to catch up to the guy ahead of you? Power is going to spike. But that’s how we ride a bike. If you think, ‘Oh, I need to stay in zone 2,’ and you’re faced with a moderately steep hill, you’d have to crawl up that hill in an easy gear, and no one wants to do that. The term ‘levels’ felt like it gave more nuance to what you can do in a ride.”
Because the training levels are “descriptive, not prescriptive,” as Coggan says, a rider can opt to go a bit harder up the hill, maybe even briefly jumping to a level 3 effort, knowing that the downhill is going to bring the average power for the ride (or interval) back down to level 2.
Power-based training isn’t meant to be utterly rigid—it’s just meant to give cyclists a more objective measure of their effort.
How do you set your cycling power zones?
If you use a training app like TrainingPeaks, Peloton, or Zwift, your zones will automatically be set after you input your functional threshold power (FTP). Don’t guess at your FTP or base it on your FTP from a decade ago—if you don’t know yours, it’s time to do a new test!
If you’re a spreadsheet and notebook kind of cyclist, you can do the calculations yourself. Using your FTP, you can create your own set of ranges by using a calculator. (This is your basic high school math class: If your FTP is 200 watts, multiply that by 0.55 to figure out your recovery power, which would be anything under 110 watts. Do the same for each zone, based on the percentage of your FTP, per the chart above.)
How do you test for FTP?
While your FTP should be the pace you can hold for an hour, most cyclists won’t do a full hour-long FTP test regularly, which makes it a bad way to test FTP, even if it is the most accurate. Because your FTP will change as your fitness improves or drops, you will be testing at least once a year, if not more often, so finding a method that isn’t a huge burden is important.
Most cyclists opt for Coggan’s coauthor Hunter Allen’s classic 20-minute FTP test. It’s a fairly simple protocol and can be done indoors or outdoors. At its most basic, the 20-minute FTP test looks like this:
- Warm up for 20-30 minutes in zone 1 and 2, sprinkling in a few 20-30 second harder efforts.
- If outside, find a flat stretch or gentle uphill grade of road where you’re unlikely to get stopped for 20 minutes worth of pedaling. Aim for minimal turns or descents. If indoors, most indoor training programs will have an FTP or threshold test workout that you can use, or just use your trainer on a manual setting.
- Time to test! Press your lap button on your cycling computer so that when you’re finished, you can easily see your average power for 20 minutes.
- Do 20 minutes hard (aiming for that threshold feeling we described above: uncomfortable, but sustainable. You should be breathing hard but not gasping for air.) Try to maintain a consistent feeling for the full 20 minutes. (For new cyclists, this test may not work the first time because you’re almost certainly going to start far too hard and fade by the halfway mark. If this happens, give yourself a week to recover and try again!)
- Hit the lap button again when you’re finished.
- Cool down for at least 10-15 minutes.
- Multiply the average power from that 20 minutes by 0.95 to get your average FTP (docking yourself that 5 percent helps bring it closer to the effort you could actually sustain for an hour).
For more on Allen’s testing protocols, check out his blog here.
Coggan actually prefers a longer effort for testing FTP, though he knows it’s not realistic for most cyclists to do regularly with their training. Still, he believes that longer efforts will give you a more accurate set of power levels, because the closer to a 60-minute test you do, the more accurate your FTP number.
If you find that the power levels you set based on a 20-minute test feel harder than the perceived exertion/heart rate, that’s a sign that you might test well for 20 minutes but can’t hold that same power for 60—in that case, you may want to retest with a full 60-minute effort to reset your power levels to better match your abilities.
Whatever testing method you choose, it’s important to stick to that method. Don’t switch between a 20-minute test and a 60-minute test, says Wilpers. Doing that will give you mixed results and won’t truly be a good way to see if your fitness is improving or declining.
Similarly, use the same road to test whenever possible. Your tests should look as identical as possible, says Wilpers. “That’s how you’ll really see improvements,” he adds.
Here’s the thing with FTP: Everybody lies. It’s tempting to round up, or to say to yourself, “I bet I could have gone five watts harder,” and set your FTP based on these, let’s say, optimistic guesses. Coggan jokingly calls this “vanity FTP.” And vanity FTP can have major repercussions, because that’s the number that defines all of your other zones. If your FTP is 10 watts too high, your endurance pace will be slightly too hard, and so on.
“The reality is that FTP is simply a representation of your current fitness level—that’s it. It’s not a reflection of you as a human being, or of how fit you can be,” says Wilpers. If you have to lie about your FTP, just lie to your friends, not to your training log.
How often should you retest your FTP to reset your zones?
Throughout the year and certainly throughout our lives, our FTP will change. After a solid base-training phase and through the racing season, it’s likely to be higher than after a long offseason. As we age, it’s likely to drop. And for new cyclists, it’s likely to swiftly improve as you get into a rhythm with training. So yes, you do need to retest your FTP and use that information to shift your power levels.
There isn’t a specific retest protocol, though. It depends on your current goals and where you are in your season. “The rate of improvement as a beginner is much more significant than that of a very experienced athlete,” says Wilpers. “If you’re improving a lot, you need to test more.”
Wilpers says beginner riders should aim to retest every four to six weeks. For advanced cyclists, testing really only happens when appropriate with the athlete’s training schedule and within the context of their season. But for any athlete, if your power levels no longer match the recommended perceived exertion (for example, if your tempo riding now feels more like the endurance riding used to), it’s probably time to retest, because you may have improved your FTP. Conversely, if every ride suddenly feels like it’s one zone too hard from a perceived exertion standpoint, that’s also a reason to retest.
Should I pay attention to power or heart rate?
Power is going to be the best objective measure of your work, but heart rate does have its place. You may have used heart rate zones to train in the past, and those still have a lot of value. Ideally, your heart rate zones and your power zones should closely align.
“I like to think of power and heart rate as stress and strain: We have the strain that is applied—the power—and the stress that is experienced—the heart rate or perceived exertion,” says Coggan. “The power that you are generating dictates the energy demand and all subsequent physiological consequences thereof, one of which is an increase in heart rate. And that heart rate combined with other feelings gives us perceived exertion, which integrates all of your internal inputs.”
If power is the objective information and perceived exertion is the subjective, is there a place for heart rate? Coggan believes that in most cases, heart rate data is largely redundant if you’re training with power, and it can even be misleading. “For example, I did a masters nationals time trial in the heat in Tallahassee, Florida, years ago,” he explains. “My average heart rate during a 40-kilometer time trial was higher than my typical maximal heart rate at my usual power for that effort, just due to the heat stress. But I was able to maintain the power I had planned to. So, what did I learn from having my heart rate displayed on my computer? If I had held back because my heart rate was so high, I would have underperformed. I didn’t need my heart rate to tell me it was hot out.” (He does add that if you have a heart condition, you absolutely should be paying attention to your heart rate!)
However, there are certain times where heart rate can dictate pace instead of power. Easier rides at recovery or endurance pace benefit the most from keeping an eye on heart rate, in addition to power. If you’re doing a recovery spin and it’s really hot out, focusing on keeping your heart rate in your recovery zone rather than trying to perfectly hit your power numbers might be preferable.
Just remember: if every recovery or endurance-paced ride led you to have a higher heart rate relative to your power numbers, it may be time to do a new FTP test to recalibrate your zones.
How do you train using your power zones?
You might be asking, “Once I have my power zones, what do I do with them?” Most training plans will have descriptions of the time spent in each zone as part of your workout. Assuming you’re training with a power meter and a cycling computer that displays your power data during your ride, you’ll follow those workouts by watching your power on the computer.
For example, a workout might look like 10 to 15 minutes in zone 1, five rounds of 5-minute intervals in zone 4 with 2 minutes in zone 1 between them, and a cooldown zone 1.
To do the workout, you can set your cycling computer up to display average lap power somewhere on the screen. Then, in the workout, use the lap button for each interval so that you can keep your average power in whatever zone you’re trying to ride. (Remember, though, as Coggan says: The power levels are descriptive, not prescriptive, so don’t stress if you have to come to a stop for a squirrel in the road, dropping your power to zero!)
Where in the zone should I be training?
Because each zone has a range, it’s important to remember to use that range, rather than always trying to ride at the very top of it. For example, if your FTP is 200 watts, your tempo power range would be 152 to 180 watts. Many people make the mistake of always riding at the highest number—rather than vacillating between 152 and 180 watts based on how they’re feeling, they feel obligated to stay at 180 watts the entire time.
“It’s important to remember that intensity is a continuum and that these zone lines are drawn to help differentiate between intensities, but they are not perfect,” says Wilpers. “Really the best place to be pedaling in a zone is usually somewhere in the middle, unless there is a reason to do otherwise, usually as determined by your coach. Always pedaling at the top or bottom effectively puts you into the next closest zone.”
The longer your ride gets, the more likely you are to be toward the bottom of that range within a zone—and that’s okay. In fact, Coggan says that’s kind of the point. “If you’re doing a level 2 ride, your average power is going to be higher if you’re at the shorter duration, and your average power is going to be lower if you’re doing the longer duration. You don’t need to strive to be at the highest end [the entire time].”
Do your power levels change when riding inside versus outside?
Absolutely, your power will change inside versus outside. In fact, there can be such a marked difference that Wilpers recommends considering your indoor FTP and outdoor FTP as different numbers. (This is also exacerbated if you have a smart trainer for indoors and a power meter for outdoors, because every device will have a slightly different calibration.)
“There’s a lot of advantages to training indoors,” says Coggan. “There’s so much convenience, and you can do very controlled workouts, you can focus on upping your power without worrying about how you’ll get home. But at the end of the day, riding the trainer is not riding a bike outdoors. There is no trainer in the world that perfectly simulates the demands of cycling outdoors.”
Handling skills, the need to stop and start depending on traffic, the wind, the heat, rain, or sleet—all of these things make outdoor riding more dynamic. That’s not a bad thing, it’s just worth remembering when your indoor numbers don’t line up with your outdoor numbers.
“Testing indoors is very different from testing outside,” adds Wilpers. “There are so many skills involved when testing outside, and power meters themselves are super sensitive. Way too many people get very attached to their trainers and the numbers they’re doing on them in the winter, and then in the spring, they get on the outdoor bike for the first time and are shocked when things don’t totally line up. So don’t panic: It’s two completely different environments.”
The bottom line on cycling power zones: It’s an imperfect science
The final word from Coggan, a scientist who’s devoted his life to power: It’s imperfect. Just like everything else.
“I like math, I like exercise physiology, I like cycling, but stirring them all together into this pot actually forced me to grow and think about the implications of the fact that our power is highly variable,” he says. “That’s why I remind people that the power levels are descriptive, not prescriptive. You’re never going to have the ‘perfect’ workout, and that’s okay.”
Molly writes about cycling, nutrition and training with an emphasis on bringing more women into sport. She's the author of nine books including the Shred Girls series and is the founder of Strong Girl Publishing. She co-hosts The Consummate Athlete Podcast and spends most of her free time biking and running on trails, occasionally joined by her mini-dachshund.