While a power meter is a great training tool that allows us to take our training to the next level, with a smart trainer, we can train indoors during winter and bad weather.
So, should you buy a power meter or a smart trainer?
In this article, you learn which one is better for your use case based on its pros and cons.
Questions to Ask Before Purchase
Before I dive into the pros & cons of both devices, ask yourselves the following questions.
1. How Much Time Do You Spend Riding Outdoors vs. Indoors?
If you are thinking about buying a power meter, you probably combine outside and indoor training. For example, if you ride 80% of your training time outside and 20% of your training indoors, a power meter may be a better option because you will use it much more often.
On the other hand, people who spend most of their training time indoors will benefit from an interactive smart trainer. It can adjust resistance based on a training app, features an ERG mode*, etc., to make indoor training more engaging and fun.
*ERG mode adjusts the trainer’s resistance based on your cadence to keep your power output the same.
2. Do You Already Have a (Dumb) Bike Trainer?
Many indoor cycling apps can estimate your power output based on cadence, speed, and resistance. However, these estimates may not be accurate.
When I started indoor cycling, I bought just a power meter, so I maximized the value I got for my money.
3. Do You Prefer Power Data Consistency or More Fun Riding Indoors?
Data consistency is important for precise and effective training. For example, a power meter may show different power data when riding outside than a new potential smart trainer indoors*. This means you will have to find out what the data discrepancy is and adjust your training plan.
*Usually, your watts indoors will be lower than outside. This difference can even reach 30 watts on your FTP. As TrainerRoad explains, this can be caused by trainer type, device calibration (zero-offsetting, respectively), your riding position, etc.
When speaking about the “fun” training indoors, I mean the interactive smart trainers. They can adjust the resistance based on the training app. This interactivity element will force you to switch gears and be more engaged.
4. What Is Your Budget?
Power meters start at around $300, and smart trainers with an in-built power meter at around $400. This means that if your budget is $800, for example, you can buy both devices.
Naturally, the low-end smart trainers are usually not interactive (there are exceptions, though) and don’t provide advanced features like ERG mode.
They are also mostly wheel-on instead of direct-drive, so they are noisier (learn more about bike trainer types in this article).
Lower-end downsides may not be as accurate and reliable. So, it depends on your preferences and whether you prefer more fun now or a long-term pleasant experience.
Power Meter vs. Smart Trainer: Pros and Cons Explained
The following table summarizes the pros and cons of power meters vs. smart trainers. I explained them more in-depth below.
|Power Meters||• Usable on a bike (indoors and outdoors )|
• Consistent power data (outdoors and indoors)
• Better for tracking your long-term progress
|• When used on a 'dumb' trainer, you won't get automatic resistance adjustments
• Left crank arm power meters can't measure right leg power so that one-leg training intervals will show 0 power on your right leg
• No ERG mode
|Smart Trainers||• Interactive smart trainers can adjust resistance based on an indoor cycling app|
• Better, more realistic riding experience when training indoors
|• Not usable when riding a bike outside|
Sources: cyclistshub.com, roadcyclinguk.com
Power meters revolutionized the training of cyclists worldwide. Unlike heart rate monitors, they provide instant, objective, and accurate data.
Thanks to this data, riders can train more efficiently and track their long-term progression. Additionally, if you use one power meter outdoors and indoors, your data will be consistent.
TIP: Learn more in this article on Why use a power meter?.
On the other hand, a power meter used with a dumb trainer provides a worse indoor riding experience.
The dumb trainers can’t adjust the resistance. They also don’t have the ERG mode feature ideal for interval and structured training.
Furthermore, one-sided power meters estimate your overall power (usually based on your left leg). If you train one-leg drills and pedal with your right leg, the app will show you zero power.
Smart trainers allow us to train indoors during bad weather or all year-round. This type of training is time-efficient, and your intervals won’t be interrupted by traffic.
Interactive smart trainers add a whole new dimension to indoor training. Thanks to indoor cycling apps that can adjust the resistance, indoor training is more engaging than training on a dumb trainer.
But of course, you can’t use them for riding outdoors on your bike.
What Is Better for Zwift: Power Meter or a Smart Trainer?
This is a legitimate question, and its answer is similar to the first question above. The answer depends on your goals and preferences.
If you plan to do a lot of indoor cycling and races on Zwift, you should consider getting a bike trainer for Zwift. You will get a much better riding experience because indoor cycling apps can adjust the trainer’s resistance based on the terrain.
But, the downside is that if you don’t have a power meter, you won’t have any power source for your outside rides.
If you decide to invest in a power meter, you can take advantage of it outdoors and indoors, but you won’t get the interactivity element with your trainer.
You also won’t be able to participate in more prestigious e-races because they often require smart trainers.
Power Meters vs. Smart Trainers Accuracy
The difference in accuracy between power meters and smart trainers is not too significant. Today’s power meters have an accuracy rate of ±0.5% to 3%, while smart trainers vary from around ±1 to 5%.
The vast majority of power meters have an accuracy rate of ±1-1.5 %, and smart trainers around ±2%.
You can learn more about the power meter accuracy in this article.
Power Meters vs. Smart Trainers FAQ
Most riders will benefit more from a power meter than from a smart trainer. With a power meter, you get accurate and consistent data that you can leverage into effective training.
Furthermore, you can use a power meter with a ‘dumb’ bike trainer when riding indoors. The only things you won’t get are adjustable resistance and ERG mode.
However, if you are a serious cyclist, you should also get a smart trainer once your budget allows you to buy one.
Interactive smart trainers have advanced features like ERG mode, can adjust the resistance based on a training app, and more. They will make your indoor training more fun and engaging.