TrainerRoad and a Tacx Flow – I’ve got the Power!

Training with power on the bike is the most effective way of measuring your performance. It’s the only really consistent way to measure your progress (or lack of) and the only real way to produce repeatable workouts regardless of conditions, terrain or your frame of mind. Unfortunately a power meter is still fairly expensive with wheel-based systems costing close to £1000 and the newer crank based systems costing more than that.

As the technology progresses these prices will come down and the quality of the products will improve but for now it’s still just a little out of my price range. The closest I’ve been able to get to training using power on the bike is on my TacX Flow turbo trainer. This turbo trainer doesn’t record true power output but it makes an approximation based on the resistance and speed. It isn’t a true representation of your power output but as long as you keep the various parameters such as tyre pressure consistent then the readings from one day to the next are comparable. It doesn’t seem too far off with the actual figures either, although in my experience when set in ergo-mode the resistance does seem to ramp up a little too quickly – or maybe that’s just me being a wimp!


With winter approaching and the prospect of more time being spent indoors on the Turbo Trainer I thought I’d give TrainerRoad a go. I’m a little late to the party on this one as I’d been avoiding it until now due to the fact that they don’t (yet) have an iPad app and my main computer is a desktop not a laptop. I was holding out for the iOS app but it hasn’t arrived yet so I’ve broken down and have started using it on the laptop PC that we have.

So, what is TrainerRoad? Essentially it’s an app that runs on your computer collecting realtime data from ANT+ transmitters and displays the readings on screen.

The website then has hundreds of training workouts that you can play via the TrainerRoad app. Most of these are interval based workouts and the idea is that by altering the gear ratio and cadence on your turbo trainer you try to match the power curve of the workout as closely as possible. Here’s an example workout (the one I did on Wednesday). The blue ‘curve is the workout that you have to try to match, the yellow line is my actual power output and the red line is my heart rate. [Note: The drop in power on the yellow line just after the second interval is where I dropped the chain on my bike when changing gears].

TrainerRoad Workout

TrainerRoad Workout

Before you start using TrainerRoad you are supposed to do a couple of test workouts that enable the software to calculate your Functional Threshold Power (FTP). The workouts you do are then based on the FTP figure. This allows the software to grade the efforts of each workout based on your ability. As you can see from the image above I managed to keep the yellow line a fair way above the blue curve on this workout so will increase my FTP figure so that next time I do it the blue curve will be following a slightly higher power setting. It is worth doing the test rides now and then so as to dial in your FTP settings.

You can also grade workouts manually yourself if you wish, for those days where you are feeling particularly good, or particularly bad!

Once set up it is very easy to use and adds an extra dimension to Turbo Training. Many of the workouts include on screen instructions and motivational text and they even have all of the Sufferfest workouts built into it . This means that  you can ride a Sufferfest workout complete with the sufferfest video playing and a TrainerRoad window showing you the power targets of each interval you are aiming for.

What do I need?

TrainerRoad collects it data from ANT+ transmitters. It can use real power readings from ANT+ power meters or it can use a feature known as VirtualPower (more on this in a mo). It also collects data such as speed and cadence from ANT+ speed and cadence sensors and Heart Rate readings too. Some Turbo Trainers themselves are ANT+ compatible so data can come directly from them, or they can come from third party ANT+ devices such as my Garmin speed / cadence sensor and Garmin Heart Rate Monitor.

You don’t need all of these, in fact any one of them will do. So all you need is a ANT+ device such as a power meter or a speed / cadence sensor and an ANT+ USB stick that receives the data from the sensor. You then also need a turbo trainer (with bike) and a laptop (Mac or PC)

I’ve got the Power

Best of the bunch is a real ANT+ power meter. In this case the power readings are accurate and the readings TrainerRoad uses are collected directly from the power meter.

Next best is something known as Virtual Power which is really the jewel in the crown of the TrainerRoad offerings. To use it you need a speed / cadence sensor (or an ANT+ Turbo Trainer).

TrainerRoad have a list of hundreds of different Turbo Trainers from all of the major manufacturers and have developed power curves for each of them. Using various algorithms they have mapped the power required to produce a certain speed at a certain resistance on a particular turbo trainer. Using the speed / cadence sensor TrainerRoad knows what speed you are doing, it then references the power curve for your particular turbo trainer in order to give a Virtual Power output reading as you train.

My Tacx Flow is in the list so by selecting it from a drop down list, making sure it is set to the same resistance level and then pedalling away I can start training using VirtualPower. It isn’t perfect of course but it does seem to work. The figures are a little different to the power figures I get on the turbo trainer itself, but the turbo trainer is using it own version of virtual power anyway and the actual figures don’t really matter. Being able to repeat the workouts and grade them accordingly is what matters.

If you don’t have a power meter or a speed / cadence sensor then it is possible to use TrainerRoad based on Heart Rate rather than power, but this isn’t as useful as training by power.

Is it Worth it?

A subscription to TrainerRoad is $10 a month, but if you already have the other kit needed (as I did) then it isn’t a huge investment and gives you a legitimate way to train using power – even if it is only virtual power.

I was able to do this anyway using the ergo-mode on my Tacx Flow which uses it’s own version of virtual power to give me power output readings. I also had a number of workouts that I did using the virtual power built into my Tacx Flow so TrainerRoad doesn’t really add a huge amount for me in that respect. If however your turbo trainer doesn’t offer virtual power then this is a great way it get it at a reasonable cost.

What TrainerRoad does offer me though is variety in the form of workouts and something to aim for. As you ride, the target power is displayed, along with your (virtual) power output. If you are on target then your little power line is green, start slipping below the target power and it turns yellow, orange or drop too far and it goes red. With TrainerRoad a workout comes down to keeping that line green, set at an appropriate level this can make your workouts really effective and keep you motivated and trying as hard as you should.

Your workouts are recorded over time so you can see how you progress and the TrainerRoad website has a ‘career’ page that shows your progress over time. For those who don’t have access to training by power (or virtual power) then TrainerRoad could be an invaluable addition to their training protocols. Even for those with access to power readings it would seem to be a useful tool for adding variety and an extra dimension to their training that may just help to alleviate some of the boredom indoor winter training. I shall probably remain subscribed over the winter and use one of their plans to provide me with an slightly more interesting range of turbo trainer workouts this year.

Just watch out – once you’ve started training using virtual power indoors you are going to want a real power meter for rides in the real world too!


5 Responses

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Avatar forComment Author

Alan Cole

Alan is a Freelance Website Designer, Sports & Exercise Science Lab Technician and full time Dad & husband with far too many hobbies: Triathlete, Swimming, Cycling, Running, MTBing, Surfing, Windsurfing, SUPing, Gardening, Photography.... The list goes on.