Fluid vs Magnetic Bike Trainers (Which is Best?)

Indoor riding can be a highly efficient and useful way to train, especially during the colder months. Completing your workout on the trainer can give you a lot of bang for your buck, but it usually isn’t as exciting as flying around the trails.

A good set up can make all the difference when it comes to tolerating or even enjoying pedaling in place. A quality set up starts with a good trainer and with so many options to pick from you are bound to find the trainer that checks all of your boxes. Here’s a breakdown to help you decide whether a fluid or magnet trainer is the best choice for your training routine.

How do Fluid Bike Trainers Work?

A fluid trainer will consist of a roller, flywheel, and fluid encased in an outer shell. As you pedal your wheel will sit on the roller. As you pedal, the fluid is pushed by paddles inside the outer shell and the fluid heats up.

The harder you pedal, the more resistance the fluid will provide and the more resistance you will feel in your pedal stroke. This undulating resistance not only makes riding more efficient, but it also has a realistic outdoor feeling.

Additionally, the flywheel, once momentum is gained, will continue to turn even if you stop pedaling for a moment. This is another aspect that allows a fluid trainer to have a road-like feel.

Pros and Cons of Fluid Bike Trainers:

Adjustability/Ease of Use: Fluid trainers will be extremely easy to use and once they are set up no adjustments are needed. Since the resistance changes automatically when you pedal you won’t ever have to pause your workout to increase the tension.

Additionally, since the resistance increases the harder you pedal, it is impossible to overpower the trainer or ‘spin out.’ This aspect will be especially important for advanced riders wanting the hardest workout.

Sensations: Fluid trainers are generally considered to be superior to magnetic trainers because they allow for the most realistic riding feeling. The resistance will feel the most similar to the resistance of the road and the flywheel will enable you to coast without feeling an abrupt stop.

This may not be as important to novice cyclists just wanting to gain fitness, but may be very important for advanced cyclists hoping to replace their training with indoor workouts.

Noise: Fluid trainers will be noticeably quieter than magnetic trainers which may be the ultimate deciding factor for people who like to workout before anyone else is even awake. Even though the trainer is quiet, the tread on a mountain bike tire will be noisy against the roller. Consider setting up a mountain bike with a slick tire such as a 40c Maxxis Refuse in order to reduce noise.

Dependability: Since fluid is involved it is possible to have the fluid leak from the trainer. I have never experienced this, but it seems to be a disclaimer that is always put on fluid trainers. A fluid trainer may not last as long as a magnetic trainer, but many companies provide warranties that may help to alleviate concern.

Cost: The biggest downside of a fluid trainer is that they are usually a bit more expensive than a magnetic trainer. A Kinetic brand fluid bike trainer will generally cost a little over $300.  

Storage: Trainers are not generally considered to be small or light by nature. A Kinetic Fluid trainer will weigh about 29 pounds and is about 16 inches tall when folded for storage.

Compatibility: You will need to take note of whether or not the trainer can be adapted for mountain bikes with thru-axles. You may need to purchase an additional part. Not all fluid trainers are mountain bike compatible.

If you really wish to enhance your riding experience, then you can look for a fluid trainer that is also a Smart Trainer and has the ability to provide wattage data and connect to Zwift.

How does a Magnetic Trainer Work?

A magnetic trainer uses magnetic forces to create resistance against the bike wheel. A magnetic trainer uses a flywheel with rotating magnets that engage and disengage in order to increase or decrease the amount of resistance placed on the wheel. In order to change the resistance, you will need to manually adjust it. 

Pros and Cons of Magnetic Bike Trainers

Adjustability/Ease of Use: A magnetic trainer is also very easy to use. Similar to the fluid trainer, there is minimal set up. The magnetic trainer, however, will require you to adjust the tension throughout your workout. Since the resistance is constant, it will not automatically increase when you pedal harder or easier.

In order to match the resistance to your effort you will either need to dismount the bike and adjust the tension on the trainer itself, or you will need to mount a cable on the handlebar and attach it to the trainer in order to be able to adjust the resistance. If you plan to use the trainer to complete interval workouts, this may be an annoyance.

Sensations: A magnetic trainer will provide a good workout and will certainly work the cardiovascular system and the same muscles as riding outside, however, it will not feel the same as riding outdoors, nor will the sensations be as realistic as a fluid trainer.

Since the resistance is constant, there will be no fluctuations as you increase or decrease your effort. You will also not have the ability to coast, because when you stop pedaling, the resistance will take over and the wheel will come to an abrupt stop.

Noise: A magnetic trainer will be significantly louder than a fluid trainer, making it more difficult to train discretely or enjoy music or television during your exercise. There are some techniques such as noise insulating mats that you can use to reduce the noise of a magnetic trainer, but you will not be able to reduce the noise all together.

Dependability: A magnetic trainer is very reliable and should last you a very long time. A magnetic trainer will likely outlast the life of your bike and certainly the life of your tires. Some brands even offer lifetime warranties.

Cost: You can find a magnetic trainer for less than $100. Since the price point is fairly inexpensive, a magnetic trainer can be a great starter tool for many cyclists or for cyclists in an environment in which they won’t need a trainer very often.

Storage: A magnetic trainer will be similar in size and weight to a fluid trainer.

Compatibility: Just like a fluid trainer, you will need to make sure that the trainer has the ability to be adapted to a mountain bike. It is likely that you will need to purchase a specific adapter for a thru-axle.

Additionally, once again, a mountain bike tire will also add noise to your riding experience and you may want to mount a slick tire when riding the trainer. The trainer will not only be louder with a tire with tread, but the trainer will run down the tread over time and limit the life of the tire.

Which Bike Trainer is Good for an Apartment?

A fluid trainer will be best for apartment living since the noise is substantially reduced. A magnetic trainer may create noise that makes it difficult for your neighbors or even downstairs neighbors to tolerate your workout sessions. You don’t want to have noise complaints or time your training for when your neighbors are away.

Both fluid and magnetic trainers are similar in size and weight so either one will require a little bit of storage space, but if you are living in an apartment with bikes you probably already have a small space dedicated to your cycling pursuits.

Other Types of Bike Trainers

While fluid and magnetic trainers may be two of the most common trainer options, there are other types of stationary trainers that may also fit your fitness needs.

Wind Trainers: Wind trainers use wind resistance in order to create tension on the wheel. Wind trainers are usually the least expensive of all trainer options but they are also the loudest.

Rollers: Cycling rollers use drums that spin when the wheels turn. Rollers will provide a very realistic riding feel because they require the cyclist to balance while riding, but not all sets of rollers will have resistance and it may be very easy to overpower the rollers during hard workouts.

Direct Drive Trainers: Direct drive trainers will replace the rear wheel of your bike and your bike will mount onto a cassette attached to the trainer. These trainers are the quietest, are fairly expensive, and have smart trainer capabilities to deliver power data and connect to platforms such as Zwift.

Indoor Bicycles: Indoor bicycle systems such as Pelotons have become increasingly popular. These indoor bikes are the most expensive, but are extremely quiet and have all of the bells and whistles, but they don’t allow you to utilize your own bike and bike fit.

Riding Indoors

Riding indoors is a great way to train for beginners and experts alike. Beginners have a safe and comfortable place to train away from the elements and traffic that may seem particularly intimidating if you are not confident on the bike.

Experts are able to utilize trainers for extremely specific workouts, hard efforts, and to continue to train even when the elements and weather make outdoor riding impossible. Luckily, there are bike trainers to fit each individual’s needs and riding styles. Pick the trainer that best fulfills your cycling goals.

Related Mountain Bike Training Articles

• Looking for indoor Mountain Bike Training Tips, Check out this article. 7 Tips for Indoor Mountain Bike Training
• If your looking to get stronger, check out this article- Indoor Mountain Bike Training {with workout plan}
• Learn how to put your mountain bike on a trainer with this article- Can I Put My Mountain Bike on a Trainer?