Functional Threshold Power: A Guide to Testing


Functional Threshold Power, or FTP, is a serious stat talked about by many cyclists. The test can help you benchmark your performance, and understand how much power you’re able to exert as you cycle. Our expert guide will help you learn about Functional Threshold Power, and how to measure it. 

What You’ll Learn:

What is Functional Threshold Power?

Functional Threshold Power (FTP) represents your ability to sustain the highest possible power output over 60 minutes. The term doesn’t solely refer to outdoor riding, and can be calculated on indoor bike trainers too. 

Why is FTP Important?

FTP is important for those cycling indoors because you can benchmark your ability and see how your training is affecting your performance.

If you are a beginner to indoor cycling who has never tested your FTP before, it provides a great benchmark on which to base your cycling specific training zones. Undertaking regular assessments will also give you a good indication of whether your performance is improving.

How Do You Measure FTP?

You can calculate your Functional Threshold Power with a Wattbike Atom smart bike or Wattbike Nucleus air bike. There are multiple ways to measure, but we recommend our very own cycling performance test:

  1. Connect your Wattbike to the Wattbike Hub app
  2. Select the 20 Minute Test on your monitor or smart device. 
  3. Complete the workout. 
  4. Your Functional Threshold Power is calculated from this 20 minutes, and your Functional Threshold Power score is measured in watts. 

The FTP test is suitable for those with an exceptional level of fitness looking to understand their training zones and fitness in more detail. If you are a beginner to cycling testing, you should know that this is not a performance test to be taken lightly.

We recommend completing the test at the beginning and end of your training plan so you can see how your training has benefitted your fitness and cycling performance. The Functional Threshold Power test will take you 20 minutes of all-out effort cycling, so you need to be in suitable shape for the test to be an accurate reflection of your fitness.  

3 Ways to Get the Most From Your FTP Test

In order for your Functional Threshold Power test to accurately assess your cycling performance, you need to be properly prepared. To see the benefits of indoor cycling you need to set realistic goals and prioritise your safety and health at all times. To see a real indication of your FTP, and complete the test properly, here are our top tips:

1. Come prepared

First things first, you’ll need to get your setup right. Be sure you are comfortable on your smart bike, choose your cycling sportswear wisely and get your indoor bike set up correctly, so you can give the test a maximal effort without worrying about any little irritations. If you are testing indoors, prep your space and ensure you have an indoor cycling fan, some hydration and a towel as you will sweat… a lot.

2. Get in condition

As the 20 minute test is a maximal effort, you’ll need to do a suitable indoor cycling warm up to prepare your body for the challenge. The Wattbike 20 minute warm up is a great option as it increases your muscle and core temperature, and offers an opportunity to mentally prepare for the performance test on the Wattbike Atom, all of which will improve your test performance.

3. Choose the right intensity

The 20 minute test is tough. You’ll need to quickly settle into an intensity which you feel you can sustain for the full 20 minutes, but also that allows you to exert yourself fully. The image below shows an even, well-paced 20 minute test:

What to do After the Test?

Once you’ve completed the Functional Threshold Power test, here’s where all the pain you put yourself through pays off. Post FTP test, make a note of your score, and make sure you eat properly to prioritise cycling recovery

Then you can use your score to work out your training zones, based on the table below:

Training Zone



Zone 1

Active Recovery

< 55

Zone 2



Zone 3



Zone 4

Lactate Threshold


Zone 5



Zone 6

Anaerobic Capacity



How Often Should You Test?

Now you’ve calculated your training zones based on your test, you may be wondering how often to test your cycling performance. The answer is, it differs for everyone. However, testing your Functional Threshold Power monthly should give you a good indication of how your performance is improving over time. 

This test is an all-out cycling workout, so testing too often will likely wear you out, and you need to prioritise your own health. We recommend only testing if you have an exceptional level of fitness, ensuring you do so without breaching the limits of your body. 

Discover More with Wattbike

At Wattbike, we’re passionate about providing the best indoor performance experience. We’re the official supplier to the All Blacks and Black Ferns, and if technical terms are confusing you, you can find our cycling terms glossary to help you unlock the world of indoor cycling.