Entering winter, as well as transitioning out of the cold-weather months and into spring, are the times riders ask us most to explain the differences between testing their Functional Threshold Power (FTP) outdoors versus indoors. The truth is, there are a lot of variances between the two approaches. However, the goal of assessing FTP is to provide an accurate picture of your fitness so that your future workouts are calibrated to the correct intensity. For now, let’s dive into why you should test your FTP and how to test it indoors and outside.
Key Takeaways
- Regularly assessing your FTP is key to ensuring your workouts are the right intensity.
- Testing indoors is the best way to control the variables, which is critical for an accurate assessment.
- The Ramp Test provides a convenient and accurate way to assess your FTP.
Why Knowing Your FTP Is Valuable
If you’re a TrainerRoad athlete, it’s likely you already know the weighty reason we advocate for knowing your FTP. Once we know your FTP, we’re able to customize every workout you do so that it’s optimized to your current fitness level. The more precise your FTP is, or perhaps better said, the more precise your FTP estimate is, the more effective your future workouts will be. That’s why, instead of going in with a previously estimated FTP, the first workout we highly encourage all our athletes to complete is the Ramp Test.
A custom training plan, automatically built for your goals.
Try Plan BuilderIf you’re not a TrainerRoad athlete, the same reasons to know your FTP apply. Firstly, once you’ve correctly estimated your FTP, you will have a benchmark of your fitness, which will help inform you in the future on whether you’re getting faster or not. Secondly, after you know your FTP, you’re able to use that information to structure your interval workouts more effectively. So, instead of going into a workout saying, “I’m going to ride at an 8 out of 10 or 6 out of 10,” you have an objective number. This allows you to figure out exactly what your power numbers need to be—no guesswork involved.
How to Calculate Your FTP Indoors
Assessing your FTP indoors is the best choice for several reasons. The most important reason is that you can control the variables much more closely than with an outside test. Aside from being more convenient, you have the advantage of limiting the number of variables like traffic, wind, road quality, and variations in pitch you would otherwise experience outside. For a scientific test like the FTP test, this is key.
Ramp Test
TrainerRoad’s preferred FTP assessment is our Ramp Test. The Ramp Test begins with a 5-minute warmup, and then every minute thereafter, it gets slightly harder until you cannot maintain target power any longer. 75% of the best one-minute power you achieve during the test is used as your FTP. The TrainerRoad app will automatically calculate this for you.
Our data shows the Ramp Test results in the most accurate and useful FTP estimate for the majority of riders using TrainerRoad. Since it is quick (typically about 25 minutes, including warmup and cooldown) and fairly easy, it can be taken frequently to track your fitness changes.
20-minute and 8-minute Tests
When performing your 20 or 8-minute FTP test indoors, start with 20 minutes of warming up, followed by your testing efforts, concluding with a 10-minute cooldown. After your test, calculate the average power of your testing interval(s) and reduce the number by 5 or 10 percent. Again, reduce by 10 percent if you did an 8-minute effort and by 5 percent if you did a 20-minute effort.
Should I Complete the 20-minute or 8-minute Test?
To decide if the 8-minute or 20-minute FTP test is right for you, consider your primary cycling discipline and your experience. For shorter duration athletes who are used to performing at VO2max, we commonly recommend an 8-minute FTP test. These are criterium racers, cyclocross racers, and cross country mountain bikers — riders who are generally more accustomed to working at this uncomfortably high workload.
For athletes who are used to putting out longer, sustained efforts in their races, we almost always recommend a 20-minute FTP test. These are road racers, triathletes, 40-kilometer time trialists, endurance mountain bikers, and gravel racers — riders who are used to laying down longer, very evenly paced efforts.
All this information aside, we designed the Ramp Test to make testing simpler without the hassle of deciding which test and removing the need for pacing. Whichever way you choose to test, stick with it. Consistency is vital when it comes to tracking progress.
Completing a 20-minute or 8-minute Test
If you use TrainerRoad, you can expect a more strategically structured warm-up when you perform one of our FTP tests. Each FTP test includes a warm-up that consists of a few big efforts—these peaks of intensity are specifically designed to prepare you for the testing intervals ahead.
The warm-up for the 8-minute test includes higher, shorter, and more intense intervals than the 20-minute test. In either case, the intense warm-up efforts we prescribe are driven by one goal: to thoroughly prepare your body and mind for the upcoming intensity. After you’ve completed your FTP test on TrainerRoad, we will present you with your new FTP. Once you accept it, all your workouts will be automatically customized to your new FTP.
Indoor Testing Variables
- Temperature. I’m talking about the ambient temperature in the room you’re testing in. You do not want to be testing in a super humid room and then in a super dry room. Try to keep the climate controlled and the same each time you test. Also, get yourself a good fan. When riding indoors, it’s essential. Place it at the base of your bike and aim it at your body, or center it in front of you on its high setting.
- Tire and trainer pressure, especially if you’re using VirtualPower. Tire and trainer pressure (how tight the tire is against the trainer) is a pretty big deal because it will directly affect your power readings. If you have a smart trainer, you’ll want to make sure to calibrate it. That said, whatever power source you’re using, it’s important to have those variables nailed down so that they’re the same each time you test.
- What you wear. We mentioned this in our winter training guide, but what you should wear when training indoors really comes back to cooling. You should be wearing as little as possible, this—especially applies to testing. Of the items you do wear, they should be your best, most comfortable pieces. Many cyclists leave their old cycling kit (worn-out jerseys and bibs) for the trainer — this couldn’t be further from the best practice. When you’re outdoors, mostly because you’re in and out of the saddle and moving more, it’s a little more forgiving if you have an old chamois. But indoors, because you’re sitting in the same position for your entire workout, it’s best to wear the good stuff. You don’t want to set yourself up to get a saddlesore, rawness, or something worse during your test.
How to Calculate Your FTP By Testing Outdoors
Many riders think that to perform their FTP test outside, they need to find a hill to reduce variables and be more consistent. The issue with this kind of thinking is that you’re inserting a huge variable just by going uphill instead of on a flat. There’s less inertia when you’re going uphill, which means all the way around your pedal stroke, you’re forced to apply more pressure on the pedals.
This can make a measurable difference in the way your muscles put down power than if you’re riding fast on flat ground. So right there is a big variable you’re inserting by assuming that your FTP estimate is the same uphill as it is on any other type of terrain.
Your best approach is to find a stretch of uniform road that you can put out power consistently without interruption for either 8 or 20 minutes. Depending on the type of athlete you are and your testing experience, finding either an 8- or 20-minute stretch of road will be more or less important to you. Put in another way: It’s best not to decide on the stretch of road you find for testing purely based on convenience, although that’s understandably a factor. Let me explain:
Once you’ve decided on the testing format that’s right for you and scouted out your stretch of flat road, here’s how to execute the day of the test:
- Warm-up for about 20 minutes. Don’t soft-pedal the whole time; mix in some bursts of intensity.
- Do your 8- or 20-minute effort. If you’re doing the 8-minute effort, take 10 minutes to recover in between your two efforts. You’ll want to take your best average power of the two efforts to calculate your FTP.
- Cool down for 10 minutes.
- Calculate the average power of your test effort(s) and reduce it by 5 or 10%, depending on the test you did. Reduce your best average power by 10 percent if you did an 8-minute effort and by 5 percent if you did a 20-minute effort.
Although it’s more difficult to reduce variables when performing your FTP test outdoors compared to indoors, there are still factors you should keep in mind and control as much as possible.
Outdoor Testing Variables
- Testing location. This almost goes without saying, but each time you perform your FTP test, it should be done on the same stretch of flat road, and whenever possible, under similar weather conditions.
- Nutrition. This is a big one. Leading up to an FTP test, make sure you’ve fueled and hydrated in a similar manner to your previous tests. And if you’ve made a mistake previously, don’t make that mistake today of all days.
- Build up. Playing off of the above bullet, try to keep your lead up to each FTP test as consistent as possible. For example, if you typically test best after two days of rest beforehand, avoid doing a really hard workout the day before your next test. It’s best to keep the week leading up to an FTP test fairly the same. You don’t have to do the same workouts, but it should be typical of your regular routine. If you’re on one of our structured training plans, you don’t have to worry about this as your FTP tests are scheduled for you at the most appropriate times.
- Power source. If you change your power source, you will need to reassess your FTP. Whether you’re testing outdoors with a power meter or indoors with VirtualPower, you can’t compare your FTP results from two different power sources. If you look at power meters alone, every option on the market is slightly different and will give varying power readings. So, stick with one option and if you change and/or upgrade, reevaluate your FTP with your new power source.
How to Calculate Your FTP By Looking at a Power File
By taking the time to do a little post-race analysis you can quickly get a feel for what your FTP is. The approach is simple: Look at a race where you’ve had to put out a consistent, all-out effort for 8 minutes, 20 minutes or even an hour. (It’s important to note this can be tricky as races are often anything but consistent, especially when you’re riding with others.) Next, calculate your average power — not normalized power — for your 8- or 20-minute effort. Finally, reduce your average power by 10 percent if you’re using an 8-minute effort or by 5 percent if you’re using a 20-minute effort.
Why do you have to adjust your average power? FTP is analogous to your hour power — or at least it’s supposed to be. For most it’s not. This has a lot to do with the mental fortitude it takes to ride at your highest possible limit consistently for an hour-long duration. This is tough!
Most athletes mentally limit themselves before their body physically does. This is the impetus of an FTP test — it’s the reason you can do shorter intervals to decipher your hour power. When you test for shorter durations, mental strength isn’t as big of a variable which means you can get a better idea of your physical potential rather than having mental limiters come into play and mess with your power results.
The longer you ride, the smaller the percentage you have to reduce your average power. Why? More likely than not, your max 20-minute effort is going to be higher than your max 60-minute effort. Same thing goes with your max 8-minute effort—it’ll likely be even higher than your 20- and 60-minute maximum efforts. That said, reductions of 5 or 10 percent are established protocols that are proven to roughly equate most closely to your true FTP, aka your 60-minute power.
What about if you have an hour-long race file you want to analyze to find your FTP? As long as it is a well-paced and consistent effort, this is actually an excellent way to measure FTP. With this approach, you do not have to reduce the percentage of your power—the estimate is what it is.
The Differences Between Testing Outdoors vs. Indoors
A lot of athletes will report they have a lower FTP when they test indoors than when they test outdoors, and sometimes vice versa. There could be a number of reasons for this, but a good one to look to first is thermoregulation. About 75% of your body’s energy consumption when cycling goes to cooling, or maintaining your body’s temperature. When you’re outdoors this is better-achieved thanks to wind and sometimes temperature. But indoors, you’re reliant on a fan or another cooling mechanism to keep your body from having to work so hard to stay cool.
We could go on and on in this section and try to dissect every little variable that could lead to a difference in test results, but ultimately I think it’s better to end this post simply: Because there are less variables to consider, assessing your FTP inside will provide more sound data, i.e. accurate assessment results, than what you’ll get outside. What’s more, because there are so many variables and differences to consider between the two approaches, you simply cannot compare your test data from an outdoor test to your test data from an indoor test, and vice versa.
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To minimize differences in power, should I use indoors also the same power-meter I’m going to use outdoors instead of using the KICKR power-meter?
Would it be possible to configure TR to use the readings from the real power-meter when controlling the KICKR in ERG mode?
Yep, that’s exactly what Nate and I both do (Jonathan too?) in order to eliminate the differences between our power meters and the KICKR’s data. We use a tool Nate created call PowerMatch and you should be able to find all the information you need right here, Simone: http://support.trainerroad.com/hc/en-us/articles/204631294-PowerMatch-Using-Power-Meters-with-Electronic-Trainers.
But to answer your question, yes, you can configure your devices such that your power meter will control the KICKR’s resistance all based on the interval structure – simply the best way to train when you have the luxury of a KICKR and a power meter. Your graphs won’t look as smooth and pretty as they do when using the KICKR alone, but the workout quality is just as high.
I actually wouldn’t suggest having anyone do shorter intervals (e.g 2×8) to estimate FTP, especially those who are accustomed to higher intensity efforts in their racing. The definition of FTP is maximum 1hr power…period. Do g anything g but that is similar a method to estimate, which is fine. So the purpose of an FTP test is to get the most accurate estimate of your 1hr power, no to maximize the estimate by manipulating the test to suit your strengths. Someone who does a lot of short hard efforts will likely overestimate their 1hr power using a 2×8 test because they are leveraging their AWC. Drop them into a 2×20′ or 3×15′ workout and they’ll likely struggle to hit the target.
Hey Joel,
Overestimating FTP is certainly a possibility with shorter tests as the shorter format is likely to allow a great anaerobic contribution, but that’s why the reduction for the 2×8-minute test is 10% instead of the 5% we use for the 20-minute format.
There’s actually a solid study (http://www.ncbi.nlm.nih.gov/pubmed/22233784) that strongly correlates all-out 8min power to 4mmol of lactate (considered by many to denote “lactate threshold” even though that’s not always the case) making it useful for our purposes here.
What’s more, the difference in lactate accumulation when comparing a shorter all-out effort with a longer one is not as substantial as you might think. (https://www.ncbi.nlm.nih.gov/pubmed/?term=Methods+for+estimating+the+maximal+lactate+steady+state+in+trained+cyclists.). This again brings both test outcomes more in line with one another regardless of which of these 2 testing formats are utilized.
But really all we’re after is a reasonably close estimate of FTP such that we can lend a good amount of structure to each rider’s training, even if that means some workouts are harder than others based on personal aptitudes and physiological attributes.
The sad fact of the matter is, anchoring training zones to a single measure of fitness will never be perfect across all percentages of that measure. In other words, even athletes with the same FTP, one measured in a lab (which still involves a bit of estimation unless you’re using a hard 4mmol) won’t necessarily be able to complete VO2max efforts at the same percentage of FTP.
Good points though! And definitely food for thought when trying to understand why some workouts are impossibly hard while others are relatively easy.
Hey Chad,
Just want to clarify – for the 8 minute test – we are taking the average power from the better of the two intervals – not averaging the two intervals together?
Thanks!
That’s right, Keith. But there’s an error in our logic (which we intend to correct but we’re trying to keep things consistent across device platforms and it won’t happen for a little while yet) at the moment and we’re in fact averaging the test results and then knocking off 10%.
This isn’t an issue when both 8-minute efforts yield similar averages, but when one far outperforms the other this can create a noticeable underestimation of FTP. In this latter case, reduce that better test’s average power by 10% and manually update your FTP so you aren’t being under challenged during your interval workouts.
Eventually, we will only use the better of the two 8-minute efforts, no averaging, and base your FTP on that effort alone.
Awesome, thanks. I think from a psychological standpoint it will be easier knowing I don’t have to equal the effort a second time. Not that I wouldn’t go as hard as possible on the second one but if I am giving it everything I’ve got but the power’s not as high as the first go it’s not gonna the resulting FTP down. I realize the difference between the two intervals is potentially informative as well.
Exactly right again, Keith.
While you may not need both efforts to get a workable estimate of your FTP, there’s some good information to be gleaned from the comparison of the 2 efforts. Besides, why not get a solid workout done when you assess?
So yep, this is NOT an endorsement to go the “one & done” route. Thanks for mentioning that!
Good article. I feel like the lower ftp indoors was glossed over rather swiftly. This is a huge subject. Do you have any conclusive studies showing actual figures for differences indoors? Sessions indoors are harder on another level, I find, and I would be interested to further understand approximately how different and why. To be honest I’d have thought turbo trainer manufacturers would be interested to get the most realistic setup but there seems to be a real lack of research when it comes to this subject. Thanks.
Hi Will,
As much as I’d like to be able to expand on some apparent differences, there is indeed a lack of research on the matter but I think it’s due mostly to the theory that capabilities indoors should evenly match those outdoors; brutal truth of the matter.
Those of us who frequently train indoors have come to recognize some distinctions, e.g. the effort is more consistent/akin to climbing a moderate grade, cooling is a major issue, motivation can be a bit/quite a bit more challenging, etc., but the idea that our capabilities are somehow limited simply because we’re on a fixed trainer indoors doesn’t hold much water with exercise scientists and coaches, myself included.
I certainly believe there are different challenges faced indoors, mostly cooling but motivation is often a factor (compare race files to outdoor ride files and you can see motivation’s obvious influence), but your body can do what it can do – and can’t do what it can’t – regardless of where it’s doing it (at least when we’re comparing apples to apples).
So while these limiting factors may take a bit of work to overcome, there’s nothing scientifically conclusive that I’ve found over the past several years that supports the notion that our capabilities indoors are inferior to our outdoors ones.
I do not agree with you Chad. Let me introduce myself and my setup…
I am a TA user for 10 months now. Training on a Wahoo KICKR, ERG mode on, with Powertap P1 pedals. So my power meter is the same indoor and outdoor. I am spending about ten hours a week on the turbo, with a good fan. As you can see, indoor training is not a problem at all for me 🙂
On the trainer, my FTP is 311w (20 minutes test). Outdoor, my FTP is around 376w. I do not test very often outdoor, but I am pretty sure that this value is accurate. I feel “easy” pushing 340w on the flat for long duration and had no problem to climb four times 50 minutes last week-end at 330w on a sportive (more than 3 hours cumulated)… Had same feeling as when I train at 85/90% on the Kickr…
Have you ever seen such a huge difference of FTP (indoor vs outdoor) for one of your athletes ?
PS : sorry guys, I do not speak fluent English…
Aurelien,
Thanks for your feedback!
I’m not sure we disagree actually. 😉
We’re not saying people don’t get different results when testing FTP indoors vs. outdoors. In fact, the article touches on why that may be the case. Thermoregulation while training indoors can require more energy than it does outdoors. This is due to the need for the body to expend more energy on maintaining a lower core body temperature; whereas outside there are cooling effects that occur. There are instances where athletes test higher inside than outside as well.
One thing to keep in mind: Even though you test different indoors vs. outdoors, this doesn’t mean you have a different FTP. Your FTP is what it is—indoors and outdoors. The issue is that several variables in certain conditions can hold you back from realizing your actual FTP (e.g. psychological barriers, thermoregulation, uncontrolled environments, restricted airflow).
We have seen athletes with huge differences and ones with no difference at all. The main rule to live by though is to train with the FTP you derived in the respective environment. So training inside with your FTP derived from an indoor FTP test will provide the most accurate power zones. Similarly with training outdoors. 🙂
PS: Your English is great!
I hope this helps clarify! Let us know if you have any other questions.
After 5 unstructured years of riding sportives and just cruising (app 100-150 hrs/yr with some intervals here and there and a few Strava attempts) this is my first TR season.
Having completed Sweet Spot base 1+2 low vol, and now at week 6 of General Build Low vol, I am SO happy that my current ftp is calculated as an average of both 8 minute intervals: First was 350, second was 333, so I ended up on 307.
If ftp had been derived from the first interval only, it would now have been 315, and as I am already struggling really really hard at 307, I am convinced that I wouldn’t be able to complete most of the workouts at 315…
I’m 46 – can my age have anything to do with it?
Hey Asger,
Much like you (and probably many, many other TR riders), I love to watch my FTP climb but I also fear the repercussions. 😉 But this is the nature of expanding capabilities, right? It never gets easier, we just get faster.
If you can average 350 watts for 8 minutes, even if you can’t repeat that effort soon after, it’s pretty likely that you could build your higher-end endurance to a point where you could average 315w over the course of a well-paced, hour-long effort and there’s a ton of science to support this likelihood.
With that said, there are myriad other factors that can keep you from nailing your workouts as prescribed, and age is absolutely one of them. Declines in muscles mass, VO2max, max & LT heart rates, joint integrity…the list goes on, can keep any aging athlete from living up to the potential enjoyed by younger athletes (and our younger selves) not facing these minor obstacles.
But age aside (and it’s worth noting that there are also advantages to being an older athlete), it could just as well be an issue of nutrition/hydration, cooling & motivation (as I mentioned just below), fatigue stemming from training and stressors unrelated to training, physiological makeup, training history…this list also goes on.
So without getting TOO hung up on the numbers, just try to recognize that all we’re really after is consistently achieving an adequate training stimulus, one that challenges our current capabilities and is enough to stir training adaptation. Does this only happen at percentages of 315w? No. Could these impacts be as effective at percentages of 307w? Quite possibly!
The most important thing is consistency. Ranked a close second to that, adequate recovery. A close third to then is this proper stimulus – not so hard it buries you to the point where you need excessive recovery but hard enough that progress takes place. So simple in theory, but something that can take a lot of trial & error to really dial in, and also somewhat of a moving target due to the challenges I’ve already listed.
If you feel like you’re pushing boundaries during your harder workouts, recovering sufficiently in between them such that you’re ready to do it again when the time comes, don’t get too hung up on exact percentages. Use them as guidelines, for sure, but not extremely strict ones.
Hi Chad ,
Great post…as always.! However can I play devils Advocate here and ask what is maybe a dumb question. As my FTP rises with each test, as it currently does, how can I be sure that my fitness is actually really improving and it’s not just a reflection on my ability to pace better through both the rest and then later through each work out ?
Thanks.
Dean
Hi Dean,
Really good question and most assuredly part of the whole improvement process. For this very reason, I try to view things more as improvements in “performance” rather than just fitness increases because there are always numerous factors at play here, conditioning is just one of them.
Without doing some form of lab work or assessment that’s mildly to wildly more invasive, we can only speculate as to where your improvement is coming from, at least in the early stages of training.
Typically, when athletes see those more substantial increases in FTP during their first foray into structured, indoor training (or simply structured training), the gains can come from a number of sources and pacing is certainly one of them.
But as riders become more adept, both physically & mentally, certain types of improvement wane – you can only pace SO well – and the increases in fitness become more prevalent overall and more apparent as true improvements in fitness.
But this still comes back to improving performance, and whether you perform better due to improved pacing, muscular & cardiovascular adaptation or more likely a combination of them all (along with other types of improvement like pain tolerance, focus, energy conservation, efficiency, etc.), the main mission is being accomplished – performance improvement.
hi Chad,
thanks for your note.
I do train with no power meter outdoor and with Tacx IFlow trainer with built in PM and Watt measurements.
I found some inconsistencies when setting the trainer for example at 250 Watt.
If riding at gear settings that enables me to make it at 90-100 rpm I can ‘stay” for much longer than if I use harder gear setup and reduced cadence as 65-70 rpm.
Since I do not check outdoor and compare rolling hills vs climbing watt output (Only HR) I wonder is due to the (lower) performance/consistency of the trainer or physical known phenomenon.
Thanks Ave
Hey Ave,
This could very well be the feel of the trainer. Certain trainers have a unique feel when riding with low cadence that don’t represent what normal pedaling feels like.
If you feel the trainer is not replicating or closely resembling a normal feel, then it may be better to just ride at whatever cadence is ideal.
Might it be worth mentioning that FTP is not a single specific number, but a range of a few %? You hint at it when describing doing FTP testing on a hill versus flats.
Many athletes, especially those new to FTP testing, get hung up on an exact number, but the level of precision and variables you can’t easily control (temp, humidity, stress, phase of moon -kidding) have day-to-day effects that cause day to day variation.
While the data is good that ON AVERAGE 8′ x 2 tests are as good as 20′ tests or 60′ all out TT efforts you sort of contradict this when suggesting that if you’re a VO2max type athlete (CX, XC, crits) you should do 8′ tests. I think this is a point worth raising. Depending on what your power curve looks like (track sprinter on one end, 40K TT’er on the other) you might get better numbers the closer the test interval is to you where your physiology is best. I do see teammates (including myself) who have optimistic 8′ x 0.9 estimated FTPs that don’t hold up to the same W/kg using blood LT testing.
Apologies, Andrew. A couple blog comments slipped by me. You bring up some excellent points, ones absolutely worth discussing.
Day-to-day variables aside, FTP is indeed a range and what a single assessment yields is unlikely to be a completely precise measurement of what you’re capable of doing – but it’s usually close enough for us to work with.
We could try to get a measure of something else like power at VO2max via a ramp test instead, and then base our power levels on that single figure, but even that has its limitations since FTP falls at different percentages of VO2max for different riders and this measure of fitness also varies with training adaptation.
So yes, don’t get too caught up in nailing exact numbers, especially when those numbers are based on a shifting basis, one that changes with training/detraining, environmental influence, levels of motivation, etc.
As far as the 8- vs 20-minute recommendations, we’re more concerned with keeping the assessment effort in line with familiar experiences in order to make the already difficult task of pacing just a little more manageable, very much in line with what you’re saying but more aimed at the psychology than the physiology.
The overriding fact of the matter is we’re working with ballpark estimates here. But as I mentioned earlier, these estimates are commonly enough to make for some highly effective training. And as YOU mentioned earlier, don’t get so hung up on exact numbers that you miss the forest for the trees. 😉
Chad how does speed and power (watts) relate to each other? I can hold 300 watts all day at 10 MPH but 158 is normal at race speeds. Is there too much concern put on FTP and not speed as a component? Also I have two FTP. One for indoor and one for out. I find that my indoor is higher due to being in a controlled environment.
Hi Ray,
I know we covered this in a podcast, but let me restate this for the blog readers. Speed relates to power in an unpredictable and inconsistent manner outdoors due to changes in weather, terrain, fitness, etc., and indoors due to differences in power meters, smart trainers & Virtual Power, etc.
So using speed as a measure of performance is really limited in nature outdoors and unfortunately, pretty useless when it comes to training with power indoors.
Thanks for the great and timely blog post Chad. As a regular TrainerRoad plan and Virtual Power user, I’m getting ready to purchase my first true power meter – Stages. I hope to start doing more of my “TSS filler” and endurance rides outdoors and the harder interval workouts indoors (with the same power meter replacing Virtual Power of course).
So if I’m to do separate Indoor and Outdoor FTP tests, how do you recommend scheduling both? Like you say above the plans dictate a good schedule for doing one FTP test every cycle, but when could I realistically do two?
Hey David,
Virtual Power will soon be dead to you. 😉
I’d recommend using your power meter for both your indoor and outdoor riding as you move away from Virtual Power since it’s basically a substitute for actual power measurement and you’re now moving into the realm of measured, not estimated, power data.
This is far less complicated and will help you maintain a high level of consistency regardless of where you train and it entirely eliminates the challenge of scheduling multiple FTP assessments.
So once your Stages is installed and you’re ready to roll, make your first workout an FTP assessment and just stick with that value, even if it differs from your Virtual Power FTP.
Thanks Chad. I’m definitely looking forward to the across the board switch to the true power meter, and plan to do a new FTP test right away as you describe. What I was really hoping for with my question though was your guidance on scheduling both indoor and outdoor tests during normal TrainerRoad plan cycles – obviously I can’t reasonably do two test workouts back to back.
Hello Chad.
I make note of your comment above…
“…..What’s more, because there are so many variables and differences to consider between the two approaches, you simply cannot compare your test data from an outdoor test to your test data from an indoor test, and vice versa….”
1) Should I be using the indoor measured FTP to set training level zones, pacing and watt/kg when training outdoors on a bike fitted with a PM?
2) Should I be using the outdoor measured FTP to set training level zones, pacing and watt/kg when training indoors on the TAX NEO?
3) Should I be using an outdoor measured FTP when training outdoors and a separate indoor measured FTP when training indoors?
4) How do others integrate outdoor and indoor PM data under the single power profile analysis with different FTP/zone levels (e.g. – Strava, TR or TP)?
5) How do I ensure PM data consistency/integrity for post ride analysis if 2 separate FTP (zone levels) are used for a single rider profile (e.g. – Strava, TR or TP)?
Cameron
Very good questions ! Look forward to read Chad’s answers…
As far as I am concerned, you should use separate FTP values for indoor and outdoor. My trainer FTP is about 12% lower than my outdoor FTP. Because I don’t test my FTP as often on the road than on my trainer, I just keep the same ratio when it increase/decrease. So if I gain some watts indoor, I assume that I gain them outdoor as well. That’s it.
But don’t get to much emphasys on your power curve when you analize your indoor workouts. If you use the right FTP value with TrainerRoad, you are doing the job, for sure !
Thanks Aurelien.
My main concern is this:
I have months of indoor related power data captured in TP. When I use an outdoor power meter (have not yet got one) on an outdoor bike – and then upload this outdoor related power data to my existing power profile in TP, won’t I be polluting the entire power data set – which is due to the difference in outdoor and indoor measured power?
I am not using TP anymore but if I am not mistaken, it was possible to set two different FTP. Otherwise, I think it’s possible at least to edit the FTP value for each workout, am I wrong ?
Hi there. Thanks again for reply. I will check TP and follow up.
Incidently, what software do you use?
Cameron
Strava (premium) and TrainerRoad, that’s it.
Hello
The power zones determined trough an indoor FTP test, can be used outdoors?
Thanks!
Hi Chad, I have a dilemma and hope you can offer some advice. I am just returning to using a power meter after 2 years without. I now live and do all my cycling in the Haute Ariege on the border with Andorra, so very hilly. Very little flat to train on at all.
So while I am waiting for my new power meter to arrive I have started to think about FTP testing. Now comes the question of terrain.
If I can find a 20 min section of flattish road, I will almost definately have to drive to it and this makes repeating the test an issue. I do have a Kurt kinetic road machine so could test inside. Problem I see with both these approaches is 99% of all my riding is on hills, up or down, so I will be constantly setting a new FTP every time I train at threshold on the hills and always auto updating my training peaks account.
Locally I have a road that is quiet, well surfaced and climbs at an average gradient of 4.5% (5.5% max) for 16km. I am thinking that I should possibly carry out 20 min FTP testing on this road, deducting the normal 5% and using this FTP for all I do in the mountains. I could then deduct another 5% if I do find myself training on the flat.
My fear is getting the strategy wrong and the obvious over training and burnout that could occur.
Which do you think would be the right approach, and if you have any other suggestions, any thoughts would be very gratefully received.
Having just done my FTP test (2×8 minute one) on TR this morning after a long lay off. Since my last time on TR I have invested in a Powerpod powermeter. So my question is, what % should I look to add to my outdoor FTP. So I can manage my TSS accurately on outdoor rides. I have read there can be a 10-20% on people that a new to FTP testing indoors.
Hey Carl,
This is a very tough question to answer because in theory, there would be no difference between your indoor and outdoor power. Assuming optimal cooling and airflow indoors, you should be able to put down the exact same power on the trainer. However, since most people’s indoor setups have varying levels of cooling, there will be a bit of a discrepency. The only way to truly determine this offset is by performing identical tests both indoors and outdoors and measuring the difference. Since this can be a large undertaking, most people spend a bit of time using trial and error to determine their approximate outdoor offset. I would say start with a 5-10% increase and see how that feels and adjust from there.
Happy training!
Thanks Bryce.
For what it’s worth my cooling wasn’t the best. So I was definitely over heating.
On the flipside isn’t there meant to be a benefit of training in a warmer temperature on the trainer?
Hey Carl,
There are certainly some benefits to training in a warmer temperature, but only in certain types of workouts- specifically steady state. You can learn more about heat adapted training by checking out this article: https://www.trainerroad.com/blog/how-to-get-faster-with-heat-training/
Ultimately, working out in hot environments does not change your FTP, but rather it limits your body’s ability to express your FTP due to the extra energy it takes to regulate your core temperature.
I hope that article is helpful!
Hi there
I just came back from vacation and starting my 24 weeks from Sweet Spot to Base and finally to Speciality. This will be my second round with TR.
My question is, is that OK to start first week of Sweet Spot with old FTP value and move FTP test to the end of first week?
My form is not at the level yet to take a FTP test and I want to warm up first before I take my first FTP test for this training period.
Thanks
Hey Erdal!
That is totally fine, you are more than welcome to wait until you are mentally and physically primed for an FTP test 🙂
Welcome back!
Hey mate, nice article!
.. This has probably been asked/answered already but here it is anyway =)
It’s my second year in cycling and have been progressively improving (power wise). How many watts can i expect “ROUGHLY” per test?
Cheers.
Unfortunately, there is no way to estimate how the rate of increase in FTP 🙁 There are just too many factors like genetics, age, athletic history, plan volume, level of recovery, etc.
For example, an 18-year-old with an FTP of 120 will likely see more gains per ramp test than a 30-year-old with an FTP of 300. As your FTP rises, the gains simply become harder to get.
All you can do is complete the training to the best of your abilities, and then see what gains that earned you 🙂
Cheers!
Hi TP, I think you’ve “sort of” answered this, but I want to make sure I’m clear: FTP is what it is, but its estimate is dependent on so many factors (mainly mental and thermoregulation). Like many others, I have a huge discrepancy between my estimated indoor and outdoor, and I know most of that is mental. However, I assume the best thing is to really use 2 FTPs to be accurate, one for indoor riding and a separate one for outdoor rides. So as not to undertrain when training outside or overdoing it for indoor sessions.
thanks!
Hey Chad,
so if I did FTP test outdoor and indoor and numberes was around 20 watts different, I do not have to worry about it?
Thank you for responding
As Chad mentioned in the article, due to the different variables seen indoors and outdoors, its tough to directly compare an indoor FTP test to an outdoor one. In general, we recommend using the FTP that you earned indoors as the basis to all of your training 🙂
Hey Chad,
so if I did FTP test outdoor and indoor and numberes was around 20 watts different, I do not have to worry about it?
Thank you for responding
Hi, not to beat the proverbial dead horse, but it seems like 2 FTPs would be what we want, indoor and outdoor, requiring 2 periodic testings. That way, we are not going too hard indoors (if using outdoor FTP) or too easy doing your workouts outside (if using indoor FTP). Am I totally off here? Since there is no way in TR of having 2 FTPs, should we just manually change the FTP depending on the activity?