How Do Bike Trainers Work? Easy-to-Understand Explanation

How do bike trainers work: Elite Novo Force wheel-on bike trainer with a mounted Canyon road bike

Bike trainers may seem like complicated devices, but their principle is pretty simple. They need to provide you with resistance when pedaling.

However, there are many types of bike trainers and resistance types. So, I did the research, spoke with experts, and wrote this easy-to-understand article on how bike trainers work to satisfy your curious mind.

Let’s dive in.

What Is a Bike Trainer?

A bike trainer is a bicycle accessory that allows mounting a bike and riding it while remaining stationary. In addition, they provide resistance when pedaling. Smart trainers can measure your ride data and transmit them to 3rd party apps.

Bike trainers are sometimes called ‘turbo trainers’ or ‘training stands.’
Wheel-on trainers are sometimes called ‘dumb trainers.’


How Do Bike Trainers Work?

All bike trainers work on the same principle. Their main goal is to provide you with resistance when pedaling.

There are two basic types of attaching your bike to the bike trainer’s frame:

  1. Wheel-on bike trainers
  2. Direct-drive bike trainers

Wheel-on trainers allow you to mount your bike without the need to take off your rear wheel. The rear wheel is then set up against a roller that provides resistance.

Direct-drive trainers require you to take off the rear wheel. These trainers have a cassette and an axle to attach your bike.

Wheel-on bike trainer Wahoo KICKR Snap with a mounted bike
Example of the wheel-on bike trainer Wahoo KICKR Snap | Source: wahoofitness.com
Direct-drive bike trainer Wahoo KICKR with a mounted bike
Example of a direct-drive bike trainer Wahoo KICKR | Source: wahoofitness.com

NOTE: You can learn more about the benefits and disadvantages of these two mechanisms in my how to choose a bike trainer article.

Types of Resistance

Trainers use one of the following four resistance types.

  1. Wind resistance
  2. Magnetic and electromagnetic resistance
  3. Fluid resistance

Before diving deeper into individual resistance types, let me quickly explain the difference between linear and progressive resistance.

Linear resistance is typical for magnetic bike trainers. Their resistance increases linearly. In other words, the resistance doesn’t increase with how fast you pedal. Instead, the trainer’s flywheel gains momentum, making pedaling easier.

Wind and fluid bike trainers feature progressive resistance. This means the faster you pedal, the higher the resistance. This type of resistance simulates outside riding conditions more realistically.

See the following chart for a better idea.

Resistance types (power curves) - linear vs. progressive vs. outdoor (for illustrative purposes only)
Power curves – linear vs. progressive vs. outdoor resistance (for illustrative purposes only)

Wind Resistance Bike Trainers

Wind-resisted bike trainers use a fan that creates resistance as it spins through the air. The faster you pedal, the higher the resistance.

There is no way to regulate the resistance of wind trainers except how fast you pedal and what gear you use.

Wind bike trainers are not very popular anymore, because they are noisy and don’t allow you to change the resistance based on your training’s needs.

Examples of wind bike trainers: Cycleops Wind Trainer

Magnetic and Electromagnetic Resistance

Magnetic bike trainers use magnets to slow down the flywheel. The closer the magnet to the flywheel, the higher the resistance and vice versa.

You can manually regulate the position of the magnet via the control knob (also called resistance selector) that you mount on the handlebar.

Elite Novo Force magnetic bike trainer and its resistance unit parts
Elite Novo Force magnetic bike trainer and its resistance unit parts

Electromagnetic bike trainers also use magnets to slow down the flywheel*, but they are controlled electronically via 3rd party apps. This means that they can simulate climbing, descending, or riding on flats, depending on the terrain you ride in the indoor cycling app.

*The flywheel can either be physical (found on most smart interactive bike trainers) or virtual (typical for Tacx NEO 2T).

Interactive smart trainers require an electricity source to provide you with the desired features.

Examples of magnetic bike trainers: Elite Novo ForceSportneer Bike TrainerSaris Magnetic Bike Trainer
Examples of electromagnetic bike trainers: Wahoo KICKRTacx FlowSaris H3


TIP: Read this in-depth comparison of magnetic vs. fluid bike trainers.


Fluid Resistance Bike Trainers

Fluid bike trainers are almost like wind bike trainers, but they use a liquid chamber with an impeller instead of an air-resisted fan. As the impeller moves through the liquid, it creates progressive resistance. This results in almost unlimited resistance.

Check out the following video to get an idea of how the inside of the fluid resistance unit looks.

Explanation of how the Kinetic fluid resistance unit works

Examples of fluid bike trainers: Saris Fluid2 TrainerKinetic Road Machine Smart 2, Elite Turno

In the following table, I summarized the advantages and disadvantages of all resistance types.

Type of ResistanceProsCons
Wind• Cheapest
• Progressive resistance
• Very noisy
• Lack of resistance adjustability
Magnetic• Relatively affordable
• Quieter than wind trainers
• Manually adjustable resistance
• Linear resistance
• Maximum resistance level
Electromagnetic• Adjustable resistance based on 3rd party apps
• Very quiet
• Expensive
• Require electricity
Fluid• Progressive resistance translating into
a very realistic riding feel
• Quieter than wind and magnetic trainers
• No maximum resistance level
• Expensive
• Lack of resistance adjustability
Pros and cons of wind, magnetic, electromagnetic, and fluid bike trainers | Sources: cyclistshub.com, artscyclery.com, youtube.com, medium.com (The Pacemaker)

I recommend reading my in-depth guide to learn more about other features of bike trainers and how to choose one.


How Do Bike Trainers Work FAQ


Conclusion

I hope you have a better idea now about how bike trainers work and the differences between individual resistance types.

If you consider buying one, feel free to read my guide on choosing a bike trainer, where you learn more about their features and which ones to consider based on your needs.

Or, you can browse the best bike trainers on the market to save time doing the research. I already did it for you.

Do you have any further questions regarding bike trainers? Let me know in the comments, and I will do my best to answer it.

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