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Tacx Neo Smart Trainer Isokinetic / Isotonic Functions

Tacx Neo

Tacx Neo Smart Trainer Isokinetic / Isotonic Functions

Whilst the Tacx Neo was initially released in 2015, the nature of the electronic-magnetic core of the unit has means that Tacx has been able to add new features over time via firmware updates. The biggest of these was probably the road feel, which people experience quite regularly on the Zwift courses, moving between tarmac, gravel and sand roads.

Tacx Neo

One aspect of the Tacx Neo which doesn’t get much attention is the Isokinetic and Isotonic control of the trainer – partially as it was a restricted function, but is now available to all. So I thought it might be worthwhile to have a look at these functions, not only as they can be useful for training, but also potential rehabilitation tools in riders returning from injury. But I imagine that most people will initially ask what ARE these two new functions? After all, they sound like the labels you see on the side of sports drinks!

Tacx Neo

So let’s take a look a the science, and then a look through the crystal ball to where things might go!

What are Isokinetic / Isotonic modes?

The prefix Iso- means equal, or the same, hence why you read about the wonders of a new isotonic sports drink. In which case, isotonic means having the same electrolyte balance as the body. Hypertonic by comparison would mean a higher concentration of electrolytes then tissue plasma – sea water for example.

In the case of muscle power, and smart trainers isokinetic refers to strength training achieved with a fixed speed of movement. Whereas isotonic means fixed tone, or set power.

Tacx Neo

So how do we use those training modes? You have to use the Tacx Utility, and then go to the Testing Dashboard screen to get to these functions, they almost feel hidden away right at the bottom, with just a couple of toggle switches. There isn’t even an explanation of what these modes are for, so let’s take a look at this for a moment.

Tacx Neo

Tacx Neo Isotonic mode

This the feature I have found the most benefit from in my training. With Isotonic mode, the Neo requires you to apply to same force right the way through the pedal stroke. I found this a little awkward, and felt honestly it felt a little bizarre – basically, the intention is to have you keeping the same tension in your muscles all the way through the pedal stroke. Which I probably don’t do as I have developed a few bad habits due to injury – which I’ll be addressing in a different post (You can look inside my knee, but no one wants to see inside my mind !)

Tacx Neo

I’m hoping that training in this way is going to allow me to get a more even pedal stroke over time, and hopefully address the issue which had me in the MRI in the first place.

To be fair, most exercises that people do in the gym are isometric in nature, bench press, pushups etc. it is actually the isokinetic function that is where Tacx have put the special sauce:

Tacx Neo Isokinetic mode

By comparison, the isokinetic mode is more of an unknown quantity; mainly this is an approach to training which has mostly been restricted to purpose-built equipment in rehabilitation facilities.

Tacx Neo

With isokinetic mode, the aim is to maintain the same speed; the Tacx Neo will not allow you to exceed a set speed no matter how much power you put through the pedals. Although normally the approach would be looking to keep a cadence constant regardless of load.

Here the Tacx Neo will be changing the resistance in order to maintain that constant speed.

Tacx Neo

So if you set the target to 17km/hr and start off putting little power through the pedals, the Neo will automatically reduce the resistance, in order to allow you to reach that speed. Conversely, if you really mash the pedals the resistance will increase in turn to keep you at the set speed by reducing your cadence,

It is very easy for a coach to request that a rider keeps a set speed, but that can actually be very hard to do. Discipline can be an issue with that – let’s be honest – as keeping a high wattage and a low cadence is physically hard work. But that is where you are going to build power. So here Tacx can force you to stick to a low cadence workout by limiting the speed you can reach. Now it’s just a case of actually getting the rider on the bike to do the training

In terms of using isokinetic mode, you can select a speed between 16-30km/hr.

So if I set my speed to 16km/hr – no matter how much I mash the pedals, the Tacx will not allow me to go over 16km/hr, which as mentioned is done by increasing the resistance and thus slowing my cadence. Conversely, if I’m not able to deploy much power due to injury, but still select 16km/hr, I’ll end up with a higher cadence, due to less power per stroke.

Given that isokinetic modes are starting to crop up on home trainers, I’d think it is something that coaches will look to use in a more focused manner, as the quality of the training session can now be improved at home. Similarly we may start to see physio and other rehab specialists looking at the Neo in a new light

Oh and to answer a simple question, can you use these modes with Zwift? You know, to keep boredom at bay. The answer is sort of. You need to select a classic trainer and use the speed and cadence from the Neo. That will allow you ride on Zwift, whilst controlling the Neo from the Tacx Utility in order to set the modes

Tacx have also been working on their general software, specifically making versions for iOS and Mac

Tacx Neo

One of the very interesting point with the software is that it allows for pedal analysis when riding. Where we get the classic doughnut shape. An interesting aspect of the way that Tacx is currently displaying the data is that you don’t simply get two traces, but four. Each leg is having two traces, the current pedal stroke, and the previous, so you can get a handle on both what you ARE doing, and what you have just done. In term helping to learn how improvements in your technique feel

Tacx Neo

Tacx Neo Road Feel

In addition to the two headline features, Tacx also gave a few tweaks to the Road Feel function, not least the ability to toggle it on and off from your Tacx dashboard.

Previously it was difficult to actually test out the road feel unless you were using simulation software such as Zwift or Tacx’s racing program. With the new update, you can choose the run the road feel at any point, merely from the app.

A good use for this may be if you are preparing for a race and using the Tacx Neo to simulate the course from a GPX file. You’ll now be able to mimic the road feel on appropriate sections of the route. This is turn may help you develop a superior race strategy compared to someone who has been doing a simple training plan by comparison

The Tacx App would also allow you to override the road feel coming from another source such as Zwift if for some lunatic reason you wanted to simulate cobbles all the way round Watopia for example.

Well, I say all the way around, there is a limitation to the road feel – it only functions during an active pedal stroke, as the simulation is from the magnets as your turn the pedals. Thus coasting, you are going to return to a smooth ride.

These may sound like daft, almost superfluous functions. In the cut-throat market of the smart trainer world, where the core abilities of Tacx Neo, Wahoo KICKR or Elite Drivo are now so refined that a purchase decision can come down to something as superficial was the look of the train, added features such as this can be vital to helping a consumer differentiate between different products.


By releasing isokinetic and isotonic modes to the world, Tacx has added another string to the bow on the Tacx Neo, and you can expect to see that these changes will be present on the Tacx Neo Smart bike when it launches. I wonder, if with these changes we may see Tacx making a push for their smart bike into the world of physiotherapy and rehabilitation medicine as well as the pain caves of Zwifters?

Tacx Neo Smart BIke


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