The Triathlete Blueprint Newsletter #127-FTP Tests Are WRONG for Most Triathletes?! Here’s Why

Yan Busset
7 days ago
8 min read

Read time: 5min.

By Coach Yan Busset

STOP Using Bad FTP Tests! Try These Methods Instead

Testing your FTP (Functional Threshold Power) looks simple on paper: choose a test, go hard, get a number. The reality is much more subtle. A poorly executed test can give you a value that looks nice on the screen but is far too optimistic in real life. And if your FTP is inflated, everything built on it will be off: your training zones become too hard, sessions become unsustainable, and pacing in races can quickly turn into survival mode. Over the years, I’ve seen a lot of age group triathletes fall into this trap because they used the wrong test or didn’t repeat it under the same conditions. My goal here is to walk you through the different ways to test FTP and related metrics, explain their pros and cons, and show you how to choose something practical that fits your level, your budget, and your goals.

The classic 20 minute FTP test

Everyone has heard of it: you do a full warm up, then a 5 minute all out effort, some recovery, and finally 20 minutes as hard as you can sustain. You take the average power of the 20 minute block and subtract 5% to estimate your FTP.

Why the 5 minute block at the start? It is there to drain your anaerobic battery so that your 20 minute power is closer to what you can truly hold for a long time. But here is the issue: most people skip it OR don’t really push all out on it. They just ride 20 minutes hard and take that number. The problem is that if you are the kind of rider who can produce a lot of anaerobic power, those 20 minutes will look great on paper but they won’t reflect what you can sustain in a real race.

Another point: the famous “minus 5%” is only an average. For many age group triathletes who don’t have the same endurance depth as professionals, you would often need to subtract 7 to 10% to get closer to your true sustainable power. Also keep in mind that many training platforms will automatically take your best 20 minute power from any ride and call that your FTP. That almost always leads to overestimation.

If you do this test properly, it can still give you a decent estimate, but only if you follow the protocol exactly and if you know how to pace yourself over 20 minutes.

Pros• Simple and easy to set up• Works indoors and outdoors• Gives a usable FTP IF done correctly

Cons• Often done wrong (5 min pre effort skipped)• Overestimates FTP for many age groupers• The -5% rule is not universal, you may have to decuct way more which make it more random• Platforms often overinflate using only your best 20min

Coach’s Rating

Accuracy: 3/5 — Simplicity: 3/5 — Accessibility: 5/5 — Overall: 3.5/5

(Overall is a coach’s verdict, not an average.)

The ramp test

Very popular on platforms like Zwift and TrainerRoad, the ramp test is simple. You start easy and the power increases step by step, usually 20 to 25 watts per minute, until you can’t continue. The platform then takes about 75% of the power from your last full minute and calls that your FTP.

It’s attractive because it’s quick and doesn’t require pacing skills. You just ride until you can’t. For many beginners it feels less intimidating than a 20 minute time trial.

But there are caveats. If you’re the type of athlete with a strong anaerobic punch, this test tends to overestimate your true sustainable power. If you’re a diesel with little top end, it can actually underestimate you. It’s also not a great way to learn how to pace long efforts, which is an essential skill in triathlon.

Pros• Fast and very easy to execute• Less mentally taxing than long tests• Good for beginners

Cons• Can overestimate if you’re very explosive• Can underestimate if you’re a diesel• Does not teach pacing for real racing

Coach’s Rating

Accuracy: 2.5/5 — Simplicity: 5/5 — Accessibility: 5/5 — Overall: 3.5/5

Going for the real thing: a 60 minute test

It sounds almost stupidly simple: instead of trying to estimate what power you could hold for an hour… just ride an hour as hard as you can. It may seem a little crazy, but if you’re an experienced and well-trained athlete who knows how to pace long steady efforts, it can be a very honest reality check.

That said, it’s not perfect and definitely not for everyone. Even strong athletes can end up a bit low if the day is hot, if pacing is off, or if they start the test tired or under-fuelled. And for less experienced riders, a full hour is usually too much: they don’t have the aerobic base or the pacing skill to hold their true lactate threshold that long, so the test often underestimates their FTP. It’s a tough effort, more of a confirmation tool for advanced athletes than a routine test.

Pros• Simple concept, no formulas or approximations• Can confirm whether your estimated FTP is realistic• Good “reality check” for well-trained athletes

Cons• Brutally demanding physically and mentally• Often underestimates FTP for beginners or less durable riders• Requires excellent pacing and good conditions

Coach’s Rating

Accuracy: 4.5/5 — Simplicity: 2.5/5 — Accessibility: 2/5 — Overall: 3/5

Lactate testing

Lactate testing has been around for decades but has become trendy again, pushed by the success of Norwegian triathletes and their famous “method.” In a way, it’s nothing new, but it’s making a comeback.

It can be a very good tool, but it’s not magic and it requires experience to do correctly. The timing of the samples matters a lot. Sweat or other contamination can alter results. One single test doesn’t tell much; to get real insight you need to do several over time, and that can become costly.

Pros• Direct insight into metabolic response• Helps fine tune training zones• Can be very accurate when combined with gas exchange

Cons• Requires experience to do correctly• Can become costly if repeated often• Results depend on proper calibration and realistic test setup

Coach’s Rating

Accuracy: 4/5 — Simplicity: 2.5/5 — Accessibility: 2/5 — Overall: 3.5/5

Lab testing: VO₂max, lactate and gas exchange

Lab tests can give a full physiological picture: VO₂max, ventilatory thresholds, lactate curves. They are often seen as the gold standard when well executed.

If you combine lactate testing with gas exchange analysis (wearing a mask in a lab), you get what many call the gold standard: you see where your thresholds really are, how your body uses oxygen, and where lactate starts to rise.

Unlike other tests that only estimate your threshold, lab testing with lactate and gas exchange actually tries to measure it directly.

But even lab testing isn’t flawless. Equipment must be well calibrated and the protocol matters.

Another key point: if you do a lab test on an ergometer that is not your bike or in a position that doesn’t match your racing position, the numbers won’t fully translate to real life. The watts you can hold on a road bike position are not the same as in a triathlon aero position. The same goes for running: treadmill mechanics are not exactly like running outside. If you want results you can use, you need to test in conditions that resemble your racing reality as much as possible.

Lab test are even more expensive that DYI lactate tests, so it might be harder to have these done frequently.

Pros:• Full physiological profiling• Very detailed data for training• Usually well supervised by professionals

Cons• Can be expensive• Results can lose relevance if test setup differs from real life

Can feel hot and restrictive with the mask, which may lower performance.

Coach’s Rating

Accuracy: 5/5 — Simplicity: 1/5 — Accessibility: 2/5 — Overall: 4/5

Power Duration & Critical Power

One big limitation of the classic 20 minute FTP test is that it is just one single effort. To really understand yourself as an athlete, it is far better to look at several efforts of different lengths. For example, you might do one maximal effort of 4 or 5 minutes and another of 12 to 20 minutes. Some protocols even add a 1 minute sprint. That short sprint is more relevant for cyclists who race criteriums or need big surges; for most triathletes it matters less, but it can still give extra context.

When you collect a few maximal efforts like this, you can build your own power duration curve. This curve does not just show your aerobic threshold; it gives a picture of your whole profile. If your short efforts are very high compared to your long ones, you are more anaerobically gifted. If your long efforts are strong but you lack short punch, you are more of a diesel. Some athletes sit somewhere in between. Knowing this helps you adapt training to your specific needs. A punchy rider might need more steady aerobic work, while a diesel might benefit from adding some top end power.

On top of this, there is the Critical Power (CP) model. Instead of simply looking at the curve, CP uses a mathematical approach to define two key things: your Critical Power and your W′. Critical Power is the line between what you can sustain for a very long time and what will eventually drain you. Ride below CP and you can keep going for hours without depleting your anaerobic reserves. Go above it and you start emptying a limited battery called W′. W′ is the total amount of work you can do above CP before you blow up. It is measured in kilojoules. Imagine a small energy tank: every time you push harder than CP, you draw from it. Once it is empty, you have to slow down until it recharges.

To calculate CP and W′, you need at least two maximal efforts of different lengths (for example 3 to 5 minutes and 12 to 20 minutes), but more data points make it more accurate. Modern software and some AI driven training platforms can even extract your best efforts from all your past rides, from 5 seconds to several hours, and fit the curve automatically. That means you do not necessarily need a dedicated test day to get your CP and training zones. This makes the method more practical and often more accurate than relying on a single 20 minute effort.

Pros• Gives a complete and realistic picture of your strengths and weaknesses• More accurate than single effort FTP tests• Profiles you as an athlete and helps tailor training and pacing• Can use data from your normal rides without a special test day

Cons• Requires software or math to calculate• Needs at least two, ideally several, maximal efforts to be solid• Less easy and instant than a ramp or a single 20 minute test

Coach’s RatingAccuracy: 4.5/5 — Simplicity: 3/5 — Accessibility: 3.5/5 — Overall: 4.5/5

Most athletes tend to overestimate their FTP, especially if they are more explosive than diesel. The full 60 minute test could, in theory, be close to the truth, but it is a monster and really not suited for everyone. Lactate and full lab testing can be excellent when done correctly and in conditions similar to how you actually train and race, but they are expensive. Modern power duration and Critical Power analysis can be done at home, on your own setup, indoors or outdoors, and even by letting software or AI models use your past rides to build your profile and zones.

Whatever method you choose, the key is to stay consistent. Test in the same position, on the same setup, whether indoor or outdoor, and remember that heat, altitude, and glycogen levels can affect the result. A test is just a snapshot of your fitness on that day; it does not define you forever. Most importantly, if you do not measure, you are guessing. Testing gives you the clarity to train with purpose, pace with confidence, and keep progressing instead of navigating by feel alone.