First ride on – 20 minute FTP test

A few days ago, a friend of a friend, @BrianDrought suggested I take a look at  I’d heard of it, but never paid much attention to it.  It’s ideal for me!  Thanks, Brian 🙂  They have a Windows/Mac application that captures ANT+ sensor data via a USB dongle (I bought the Suunto Mini MoveStick).  It’s a cinch to pair whatever ANT+ devices you have (heart rate monitor, speed/cadence sensor in my case) and you’re away.  It will also pair with a power meter if you have one.  The killer function though, for those of us without power meters, is their concept of virtual power.  They have a very long list of turbo trainers for which they have either measured the power curve for different speeds, or where the trainer’s manufacturer publishes a power curve.  Measured power response is better, but unfortunately my turbo is one of those they don’t have a verified curve for, and are relying on Tacx’s published curve.  Oh well.

The service costs $10 per month, for that you get access to over 100 rides and workouts.  Each one is tailored to your specific level.  The rides consist of a number of intervals with an indicated power level you should aim at for that interval.  As you ride, your live power and heart rate is overlaid so you can see how well you’re matching the plan.

There’s a variety of display options, you can see the data full screen and resize the text  (ideal for the myopic among us, myself included, or you can watch a video,or have anything else going on in the background, with the TrainerRoad software displaying a thick ‘toolbar’ with your data at the bottom of the screen.

Another excellent feature I will be taking advantage of is SufferFest integration. videos are video cycling workouts to music, the video footage usually being Tour stages, so you can ‘ride along’ with Sir Bradley & Co.  The Sufferfest rides are split into intervals, similar to TrainerRoad’s workouts.  I have two of these videos and they’re very good.  You can import them into TrainerRoad, each video has a corresponding workout, whose intervals exactly match the sections of the video.

In order to match the workouts to your fitness level, TrainerRoad needs to know what that level is.  The recommended first step is to perform a test, either an 8 minute or 20 minute FTP (functional threshold power) test.  The longer the test you take, the more accurate it will be, so I chose the latter.  Although it’s a 20 minute test, the ride is actually 60 minutes long.  The solid 20 minute test starts after a structured 30 minute warm up.  The idea is to ride that 20 minutes at the highest power you can sustain, but not to burn yourself out – you need to try and maintain constant power.  The result of that ride is below, and you can see the actual data on if you click here.

Screen shot 2013-02-09 at 14.31.26

The blue blackground shows the plan for the session, you have to try and match this.  But the height of the blue bars is based on your existing FTP.  I did a 60 minute ride last week to establish a baseline and measured 253 watts on the Tacx.  So I entered 250 watts as my existing FTP to see if I could ride to that level in the test.  If you have no idea of your existing FTP, the default setting is 200 watts, and you can start with that and see if you can match it, or you can edit it up or down. It’s only a guide, and it’s entirely up to you how hard you pedal.  The big blue block in the second half of the ride is the interval they use to calculate your FTP.  FTP is (roughly speaking) the maximum power level you can sustain for an hour.  The 20 minute test is a standard way of deriving it, the generally accepted formula is FTP = 95% of your 20 minute power.

The yellow line is my overlaid power output.  Again it’s worth pointing out that this is being estimated, not measured.  The TrainerRoad software understands the power curve of the trainer (or an approximation of it) and it knows your speed, so it derives a power reading from that.  Once I got into normal operating range (150 watts+), the reading on the Tacx head unit matched the TrainerRoad reading very accurately.  Below that, there was a few watts discrepancy (less than 5).  The red line is heart rate.  As expected, this follows your power curve, lagging behind a short distance.

I must say that this test is not a pleasant experience.  I quite enjoyed the 60 minute session I did last week, because you can’t hammer it and hope to last that long.  You have to find the maximum level at which you can continue without having to back off.  For the 20 minute test, however, you have to ride above that level.  You can see that although the input FTP was 250 watts, I was being asked to ride above that (266 watts to be exact).  This is not fun, because you deteriorate.  You’re riding at a level that you know can not be sustained.  If you look at the red heart rate line, it’s creeping up throughout the test.  I kept the power output a few watts above the test level for the majority of the 20 minutes, which was quite hard to do.  The yellow power line leaps up at the end because I gave it all I had for the final minute, before you then go into a cool-down period.

After the test, you’re prompted with the new calculated FTP and lactate threshold heart rate values to use for future workouts.   You can accept these, or edit them.  Once you change your FTP, future workouts are scaled accordingly, and you can manually scale them up and down yourself.  My new suggested FTP was 257 watts, lactate threshold 146bpm.  I will be trying to work to that level for the next little while.  They recommend re-testing every now and then.  Not looking forward to that!

You can export the data as a TCX file (Garmin format, I think) which can be uploaded into Strava, if you use it.  I uploaded my ride here.

If you’re interested, there is a good introductory video to TrainerRoad below.  I have limited experience so far, but I can’t speak highly enough about it.  I can’t find fault with it.


Posted on February 9, 2013, in Uncategorized. Bookmark the permalink. Leave a comment.

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