Functional Threshold Power (FTP) is one of the key performance metrics for cyclists who want to train and race with power.

It is generally defined as the maximum average power, measured in watts, that a cyclist can sustain for an hour.

While this has applications in its own right if you race 25-mile time trials in the UK, for example, its a very useful figure to know if youre racing with a power meter its more commonly used to set training zones and for measuring improvements (or deteriorations) in fitness.

FTP is also one of the key figures used to determine all manner of things on Zwift, such as training zones and race categories.

Dont worry if this is all Greek to you though, because you can check out our full guide to FTP and why it matters for the full run-down. Here were going to focus on how to use Zwift to complete an FTP test.

While you can complete an FTP test on the open road, it can be difficult to find a suitable stretch of tarmac, free of interruptions such as junctions, traffic lights, road works and congestion. Given how downright unpleasant an FTP can be, theres nothing worse than having to stop your effort after 15 minutes.

Using the turbo trainer removes those variables and allows you to focus on producing your best performance.

Zwift is the ideal platform to test your FTP and for power-based training. Zwift

Before you embark on any kind of training plan, like those available on Zwift, its worth setting a baseline FTP figure for a couple of reasons.

Matt Rowe, of Rowe and King Cycle Coaching and host of the Zwift Power Up Cycling Podcast, says that having an accurate figure for your FTP is vital because its used to set you power zones.

If your power zones arent accurate, youll be training in the wrong zones, and not targeting what youre intending to, says Rowe.

Having a baseline figure from the very beginning of your training plan will also allow you to know how much progress youre making throughout the plan.

Get a couple of weeks under you belt, then get stuck in, he says. Youre not going to get a great score, but it helps establish where youre at.

Its particularly relevant at this time of the season, Rowe adds particularly if youre just coming back to training after a break. You might be a long way off where you want to be but, at this time of year, thats where you should be, says Rowe. Setting an FTP now will help you to evidence your improvements later on.

One of the main reasons to use Zwift is that it makes it all very simple the test protocols are well signposted and easy to follow. This also means its very repeatable, so you can be sure that your results are comparable every time.

If you have a smart trainer, then Zwift can also use ERG mode to control the resistance of the trainer to ensure you hit the specific power levels required in a ramp test, or in the warm-up for a 20-minute time-trial test. Weve cover those options in more detail below.

Once youve set your FTP, Zwift can then adjust all of the workouts and training plans to your specific level of fitness.

Youll also then know which race category you fit into, based on your current fitness level, because these are decided according to FTP in watts per kilogram (w/kg).

There are three FTP tests on Zwift: two classic tests, which involve a 20-minute max effort, and a ramp test. Zwift

Outside of simply riding as hard as you can for an hour (which is very hard to pace correctly and can also be pretty dull), there are two main ways to test FTP, both of which are available on Zwift.

First, theres the traditional 20-minute time-trial test. After a warm-up, you perform a 20-minute interval at maximum effort. Record your average power and then subtract 5 per cent to determine your FTP (Zwift will do this automatically for you).

The second way to calculate FTP is to perform a ramp test. As the name suggests, the ramp test involves performing intervals at ever increasing power levels until failure. Zwift then calculates your FTP based on 75 per cent of the maximum power interval that you reach.

If youre new to Zwift but you already know what your FTP is, you can manually enter it on your profile page or on the workout page it displays your FTP on the bottom right of the window, and to change it you simply need to click it.

Alternatively, Zwift will calculate your FTP from general riding in the game or from racing. Zwift will automatically calculate your FTP on every ride, using the maximum 20-minute average power you record on each ride, but will only notify you if it detects an increase over your current score.

However, the best way is to perform one of the three specific FTP workouts available in the training page on Zwift.

The first workout, which is simply called FTP Test, is Zwifts standard protocol.

It starts with a long, easy warm-up, followed by a few ramps and a 5-minute effort. After that, you get a rest period, before performing the 20-minute maximum effort test interval.

Zwift will then subtract 5 per cent from your average power during that test interval to extrapolate it out to an hour.

For example, if you average 300 watts for the 20-minute test interval, you FTP would be 285 watts.

The shorter FTP test simply ahortens up the warm-up the 20-minute max effort test interval is still just as long. Zwift

The second FTP test on Zwift is called the FTP Test (shorter). Its simply a compressed version of the first test.

The 20-minute maximum effort test interval is the same, so its not any easier, the only difference is that the initial warm-up is shortened to save time.

This test has the advantage of being a reasonably long interval, so it tests your aerobic capacity very well and can give accurate results. However, Rowe says it can be a daunting task for many people, because its always going to be a very hard test and is difficult to pace properly, especially for beginners.

With that in mind, Zwift has recently introduced a different kind of test; the ramp test.

The ramp test is intended to be a more manageable way to test your FTP. Zwift

As the name suggests, the ramp test involves performing intervals at ever-increasing power levels until you cant ride any further.

Rowe says the ramp test is more manageable than the 20-minute test, so people repeat it more often and therefore have more accurate zones as their training progresses.

Another benefit of the ramp test is that the result depends less on pacing you simply keep going as long as you can.

On Zwift, after a brief warm-up, the ramp test begins at 100 watts, then increases by 20 watts each minute. At first, it should feel easy, but it will eventually get very hard (how long that takes will depend on how strong you are the test continues as long you can keep holding the power).

Zwift will then take 75 per cent of the maximum power you reach on the test as your FTP.

No matter which workout you do, Zwift recommends staying seated for the duration of the test effort, because this helps to keep your effort and technique consistent throughout the intervals.

In terms of how often you should be retesting your FTP, Rowe recommends doing so once every six to ten weeks, or at the end of each training block preferably after an easier few days so that youre well rested.

You might think it would be useful to test more often, to keep your zones as accurate as possible, but Rowe says that any more often than that and you risk getting bogged down with testing rather than training.

At the end of the test, Zwift will notify you of your score. Hopefully you will have improved, but dont fret if not sign up for one of Zwifts training plans and kick-start your winter riding. Zwift

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Once you hit the test part of the session, you dont want to pause or take any sort of breaks, because doing so will spoil the data.

With that in mind, its vital to ensure your indoor training setup is running as efficiently as possible: make sure youve fuelled correctly, have a full water bottle to hand, a fan to keep you cool, and youve got some suitably motivational music lined up to last the full duration of the test.

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When pacing an effort such as a 20-minute power test, its very easy to go out too hard and end up finishing with a whimper or vice versa. What you really want to do is ride right on the limit of what youre capable of for the entire duration of the test which might leave you wondering how you are supposed to know where that limit is?

British cycling legend Chris Boardman once suggested a method whereby you simply ask yourself, Is this current effort sustainable for the remaining duration?. If your answer is yes, then youre going too easy, if its no, then youre going too hard. What youre looking for is maybe.

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Although hitting huge numbers in the lab/shed/spare room can be exhilarating and hats off to all those who do it the final figure isnt the be all and end all of cycling.

An FTP test isnt a race there arent any prizes for getting a great score, and getting a low score doesnt mean youve lost anything either its simply a personal performance benchmark and everyone is different.

Sign up for one of the many training plans available on Zwift and try to focus on the process of self-improvement, rather than the specifics of the raw data. Unless youre a professional, having fun is what matters, after all. The numbers are just that numbers.

Simon is a freelance writer and photographer, who has been riding bikes for fun since he was a kid, but took a deep dive into road racing, crits and time trialling culture whilst living in London in his twenties. As a man of very little talent, he always looks to tech to compensate and loves nothing more than finding a smart (preferably cheap) hack that others hadnt thought of. His stable of bikes certainly isnt the most extravagant, but theyre all customised to meet Simons particular tastes and kept fastidiously clean. His current No.1 bike is a 2009 Giant TCR Advanced SL, that he purchased second hand from a friend in London he maintains that the 2019 TCR is basically the same bike, so why bother upgrading?

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How to take an FTP test on Zwift to kick-start your winter training - BikeRadar.com