1. The Folklore:

Low indoor power output due to boredom and heat?!

It is common knowledge that people put out less power indoors than outdoors. If you have ever measured your power with the same power meter indoors and outdoors, you probably found the same.

The common folklore is that this is due to boredom and heat. But the more we thought about that, the sillier it sounded. In a basement with a fan you are a lot cooler than on a mountain climb at a slow speed with the sun burning down on you. Also, riding the same training route as you usually do is a lot more boring than watching Mr Willis save yet another building or The Avengers yet another planet, right? And in that burning sun or on that boring training lap you do put out the powers that you are capable of.

True Science

In the Mieras study people were asked to ride 40 km at a fast pace without knowing how fast they were going, nor what their heart-rate was. The results were shocking: indoors the subjects delivered less power. During the Bertucci study people were asked to ride at various levels both indoors and outdoors. When asked how strenuous it felt, the subjects consistently indicated that indoors felt a lot more strenuous. Moreover this study found that the force profiles indoors were significantly different from outdoors! The conclusion of both studies is: “If you have the possibility, you can better train outdoors.” But not everybody has the time or finds him or herself in a location to ride outside whenever they want. That is where the TrueBike and TrueTrainer come in: We bring the outside to you!

True Reasoning

So indoor cycling should be seen as a sport different from outdoor cycling. Otherwise it would feel the same and you would put out the same power. But don’t take our word for it. There is a large body of scientific work that shows this. People deliver less power indoors (Mieras, 2014) or they find it a lot more strenuous (Bertucci, 2007).

Mieras et al, 2014

This study shows us that cyclists are producing significantly less power during indoor cycling compared to outdoor cycling. Mieras tested this by having people cycle a 40 km time trial indoors and outdoors.

Bertucci et al, 2007

Bertucci had people deliver the same amount of power at various crank rotation speeds.

2. The Truth:
Different muscle loads

The science behind the TrueForce Technology

The science behind the TrueBike and TrueTrainer is simple and straightforward: we bring outdoor cycling indoors. By replicating the resistance on the pedals during cycling outdoors, we are able to achieve the right neuromuscular load indoors.

Let’s have look at the picture below. When you ride outdoors you activate your muscles in a very distinct pattern as shown on the right force circles: Most of your power is put in through the big muscles in your legs: your buttocks first, and then your quadriceps. These are very big and strong since you constantly use them for standing, walking and running.

The current indoor trainers, on the other hand, have a flywheel that is supposed to represent the inertia of your body (and bike) weight that you experience outdoors. In reality, however, that flywheel is usually a factor of 10-20 too light, resulting in pedal forces that look much more like the force circles on the left: Only little force can be put into the lightweight flywheel because it accelerates quickly as you start pushing. This is the whining sound you hear with every push: the speed of the flywheel increasing. As a result your buttocks and quads cannot push as hard as they want.

Stand still vs. Rolling for minutes

But then, when you reach the top/bottom dead-point the light-weight get’s slowed down a lot by the simulated wind, road and climbing resistance. You notice this when you stop pedaling: You come to a standstill within seconds whilst on the road you roll for minutes. So to keep going you have to use the muscles in your calves, the back of your legs (hamstrings) and even the muscles that lift your knees. Since this is very different from reality, these muscle groups are not well trained and therefore tire much quicker.

So by training on the TrueBike, the idea is that you get even more from your workout, by getting the same neuro- muscular stimulation (i.e. your muscles are loaded with the same forces and contract at the same speed) as you do outdoors. That way you train the way you would train outdoors.

Muscle Activation

The left force circle represents outdoor muscle activation.
The right force circle represents indoor muscle activation.

3. The True Solution:

A new approach to cycling

The TrueBike and TrueTrainer take a completely new approach to indoor cycling. We don’t use a flywheel at all. Simply because we don’t know what you weigh, but more importantly because we are pretty convinced you don’t want an indoor trainer that weighs 450 kg (1000 lbs). Because that is what it would roughly take to have an accurate simulation of your weight on the road. Seriously: how would you get that to your attic, and how would you keep it there?! Why so much? Well then we get into some real boring stuff with rotational moments of inertia, bearing choice and safety measures.

So instead we use a very strong robot. A robot that continuously calculates where your pedal should be and then moves your pedal to that position, no further, no closer. How do we know where your pedal should be? Simple math: we measure the force you exert on your pedal and then we plug that along with the position of your pedal, your weight, your speed, the incline of the road, etc. into the laws of physics and voilà! We know how to supply you the right resistance force.

10,000 measurements per second

In order to do this accurately, we adjust the resistance 1000 times per second, and we take measurements of you and your TrueBike or TrueTrainer close to 10,000 times per second. That is simple math done very quickly by our robot.

Also, since your pedal push is strongest when you move the slowest, we don’t rely on electro-magnetic (also called Eddy current, used in most higher-end indoor trainers), fluid (viscous) or wind forces to guide your pedals. We use a very strong motor in our robot, straight out of a car. Since we labelled this section the science section we will show you in a graph. As you can see, a motor can deliver a force, even at standstill (also known as the holding torque). This is how cranes and elevators work. They can hold your weight like we can hold your pedal force, even at low speeds.

That gives you the unique sensation when standing up and riding up a hill: Your pedals hold your weight and you don’t fall through! But … there is a limit here. Due to safety and wear considerations, you can go down to about 30 rpm and below that even our motor gets a bit sloppy with its placement accuracy (normal cycling is between 80-100 rpm).

Maximum pedal force as a function of rotation speed of rear axle. This means that if you cycle at low rpm or cycle in a low gear, the maximum resistance of the existing smart trainers is very limited.

The Design of the


Electric currents mimic body weight

We have made a couple of important choices in the development of the TrueBike and TrueTrainer.

First, we have chosen not to use weight to mimic your body weight. Because the kinetic energy that is stored in your body and bike when you are traveling at 40 km/h (25 mph) is astounding. Think of how long you need to brake at your hardest if you are traveling at those speeds, or maybe more vividly, think of the carnage if you would hit a wall.

We didn’t think it was a good idea to put that kind of energy in your living room. In fact, nobody does, that is why all the trainers and spinning bikes have such low-weight flywheels (even though the whole machine is quite heavy).

To put in realistic weight at the speeds required would require a whole different type of safety and construction. So we use electric currents (very big currents) to solve this issue. The cool thing about currents is that you can dump them almost instantaneously.

Lean and Green Technology

Second, the TrueBike and TrueTrainer have to be future-proof in the face of sustainability. The TrueForce Technology is a more durable and environmentally friendly option as the TrueForce Technology generates its own energy using your pedal strokes. When you pedal, the energy of your pedal strokes is converted into energy and used to run the TrueBike and TrueTrainer. Contrary to traditional indoor trainers, there is no hassle of cords and cables through the house and you can save energy and money on your utility bill.

A Dutch Frame Designed For Performance and Comfort

When cycling indoors on regular trainers, you will notice that the trainer feels very static and even can cause saddle discomfort and lead to injuries. In case you experience any discomfort, it can take all the fun out of indoor cycling and you may skip your workouts altogether.  As a solution, we have designed the TrueBike and TrueTrainer for maximum comfort and performance with multiple ingenious features

One of the key features we have included for the TrueBike and TrueTrainer are flexible feet caps underneath the frame to simulate a built-in rocker plate.  On traditional indoor trainers, you may find that the ride feels static and even experience extreme saddle discomfort or knee pain that can distract you from training. For these riders, we have provided the TrueBike and TrueTrainer with flexible feet caps that simulate a built-in rocker plate. The TrueBike and TrueTrainer move slightly side-to-side during the training to feel more like outdoor cycling and help you to put out more power on your climbs or sprints. Furthermore, it helps to redistribute the weight on the saddle and reduce pressure on your glutes, hips and knees. A flexible frame helps to alleviate symptoms and helps you ride for much longer.

Another key feature of the TrueBike’s frame is the ability to adjust the height and reach measurements of the aero bar and saddle with just one hex bar. In case you have ever done a bike fit, you can transfer and apply the measurements to the TrueBike and TrueBike Base so it feels just like your own road bike and you can focus on your performance.

Modern and Sleek Design

The TrueForce Technology allows us to use durable and lighter materials. The TrueBike Base weighs just 38 kilograms and the TrueBike 40 kilograms, and both are fitted with wheels to easily move around the house. The TrueTrainer is at just 15 kilograms the lightest turbo trainer on the market. The foldable legs allow you to easily store the TrueTrainer after each use.

But the benefits of our frames go beyond just performance and durability. Our products are also designed with aesthetics in mind, featuring a sleek and modern design with little to no cables that complement any home gym or fitness studio. With their sleek lines and minimalist styling, the TrueBike and TrueTrainer are sure to impress and inspire, making them the perfect addition to any fitness enthusiast’s collection.

Transform your indoor training

The indoor smart bike that makes your indoor ride as smooth as outside. Award-winning technology.
TrueBike Base home
TrueBike Base
The award-winning TrueBike with a smaller footprint and the same big punch.
TrueTrainer 6.2_smart_direct_drive_bike_trainer_main
The smart direct-drive trainer that adds power to your cardio. Award-winning technology.

Trusted by pro athletes

World Champion cyclists, Olympic speed skaters, and Ironman-winning triathletes use our trainers to compete for the biggest prizes in their sports. 

Our partners