Power Meter or Smart Trainer: which one to buy first?


If you are a keen cyclist who wants to improve your wattage to be stronger and faster: you probably wonder if you need a power meter or a smart trainer. Assuming you cannot buy both devices, which one should you buy first that will bring you the most benefit?

It is best to buy a smart trainer before a power meter. Smart trainers include a power meter while making your indoor training enjoyable. Their accuracy is similar to dedicated power meters. But power is best used for targeted training sessions which are easier and safer to do indoors.

This question is very interesting to review as both power meters and smart trainers are very efficient tools to improve your fitness and cycling level. But sadly they are both expensive pieces of kit and it is not possible for everyone to buy both. So let’s see how to choose which solution is best for your need.

Metrics to consider for performance training

Monitoring your average speed is a good way to start your cycling journey. The next factor to add to your training is to record your heart rate as it gives lots of information about how hard you are pushing. But heart rate is a parameter that varies with your condition: dehydration, anxiety, fatigue, illness, and even the heat/cold from outside. So it is not the most reliable parameter to base your training on.

The most accurate parameter to train and improve your fitness level is the power: the watts! Power is calculated as the force times the velocity. It is a quantitative measure of the intensity of a ride. And the good thing about it is that it is reliable and repeatable.

When combining power and heart rate monitoring, you get a full picture of your ride. It adds context to your heart rate data.

Example of key metrics recorded during a ride

Power meters allow measuring power. To train with power: you can either buy a power meter unit (in the form of pedals, or crank) for your bike or buy a smart trainer which includes a power meter.

Benefits of power meters

Power meter units use strain gauges to measure the force you apply while riding. They obtain the power (measure in watts) by measuring the torque applied and combining it with the angular velocity. Power meter units come in different forms since you can measure the power from different locations on the bike:

  • Crank arm power meter
  • Pedal based power meter
  • Bottom bracket power meter
  • Chain ring power meter
  • Hub based power meter
Locations of the different types of power meters on a bike to visualize

All forms of power meters are interesting, with pros and cons for each one. For instance, pedal types power meters are usually less accurate but they are easily transferable from one bike to another and measure the power in each leg. Chainring and hub-based power meters were introduced first in the market. They are very accurate but more difficult to fit onto the bike.

In terms of pricing, the cheapest units come at $300. But most power units figure a price tag which averages $1000, especially with power meter pedals.

So what are the benefits of power meters units?

  • Metric always available when riding your bike.
  • It provides a very insightful knowledge about your cycling capabilities. If you use it regularly when training, you will know during your next race how much you can push yourself, or if you are already overdoing it and won’t last till the end.
  • For some types of power meters, you can take easily the unit with you when you ride another bike.
  • You can use the data to build up specific training sessions.
  • You can train with power both indoors and outdoors (while smart trainers only work indoors).
  • Most power meters have a margin error of about 2%.

Benefits of smart trainers

Smart trainers are turbo trainers which can be controlled directly via a training app such as Zwift, Sufferfest, TrainerRoad… It simulates directly the power in your legs at the same time as it is written on the screen. For instance, in Zwift, if you are riding up a hill with a 6% gradient slope, you will feel in your legs an increase in difficulty, same as riding a hill outdoors.

Smart trainers are the best companion when the weather is your best enemy :p

Without joking, smart trainers are great for the winter months. Rain, wind, cold and dark can be unsafe for cyclists outdoors. It can a be sensible option to train indoors.

Smart trainers are like turbo trainers – they allow you to ride your bike indoors – but with the added benefits of having the resistance directly controlled by an indoor cycling app, such as Zwift. Smart trainers include a power meter.

Examples of smart trainers

In terms of price you have 3 types of smart trainers:

  • $350 – $700: this low-end range includes a mix of wheel-on and direct drive smart trainers which are limited in term of power they can provide: generally between 800W and 1500W (simulating a slope between 6% and 12%) and with an accuracy between 3% and 5% for the power.

  • $700 – $1000: this mid-end range includes direct drive smart trainers. These smart trainers are similar to the high-end smart trainers except they usually lack of road feel and accuracy (about 2.5%). They can provide up to 1750W (15% incline).
  • >$1000: this high-end range contains only direct-drive smart trainers. They provide up to 2200W (20 to 25% incline depending on the model) with an accuracy of about 1%.

So, what are the benefits of smart trainers?

  • Realistic indoor training (high-end models are really ideal for that)
  • Power data always on your screen – at the center of each training session
  • Can simulate any course you want, including a future race to prep for it
  • They provide an ERG mode: it’s a special mode where you can do workouts with the power setup for you. It’s great for interval training.
  • Only working indoors – but perfect to avoid unsafe rides in bad weather or night time conditions
  • Power margin of error is the same as power meter units for mid and high-end smart trainers.

Power meter VS Smart trainer for most effective training?

We have seen that power meters and smart trainers are both great tools for training and both quite expensive. If you can only buy one, which one would provide the best benefit for your training and to improve your cycling performance?

In my opinion, a mid-end to high-end smart trainer brings more benefit to your training than getting a power meter. Indeed, even if you can use a power meter outdoors, you will notice that with traffic and signalization, it can be tough to keep your eyes on the data, and even worse, to complete a workout entirely without being interrupted.

Outdoor vs Indoor Power Training

Owning a smart trainer will also give you opportunities to ride indoors. It can be useful if the weather is bad to keep you safe, especially with strong winds and rain. It is also true for riding after work in the winter when the night is already there. It is easier just to ride indoors and safer. But also for busy people and parents, owning a smart trainer allows you to do more things in your day, as you can just hop on hop out when you want. And for parents, you can keep an eye on your children while being on the trainer.

But for me, the most important reason to choose a smart trainer over a power meter is the workout experience. With smart trainers connected to an app, you can get a big variety of workouts already made to use when you want. You also have access to full training plans over a specific number of weeks to target different cycling skills (endurance, FTP, etc). Even better, you can do these workouts in ERG mode which feeds directly in your leg the resistance corresponding to the power you need to produce at each time of the workout. It’s a great tool to be more consistent with power input when you go back outdoors.

Another good benefit of choosing the smart trainer over the power meter is that each time you will ride outdoors, you can just focus on enjoying your ride! It makes outdoor rides even more enjoyable. Plus if you do club rides also, there is no point in owning a power meter for them.

Using a smart trainer for doing specifically designed workouts to increase your performance, while keeping outdoor rides for club rides, long rides, and racing, is I think the best compromise!

Related questions:

Do you need a power meter if you have a smart trainer?

Nowadays, smart trainers include accurate power meters and are able to simulate very realistic indoor rides. Owning a power meter won’t make a difference indoors. As for the outdoors, they are a great piece of kit to have but you can lose the fun out of cycling by focusing all your rides on metrics!

What about a power meter with a ‘dumb’ trainer?

You can consider buying a power meter for your bike and also a dumb trainer to allow you to ride your bike indoors from time to time. What I call a ‘dumb’ trainer is a classical trainer where unlike a smart trainer cannot be controlled directly by an indoor training app.

I would not recommend this solution. I can bet you won’t spend more than 40 minutes at once on the dumb trainer. It feels really different from an outdoor ride and is not enjoyable in any way. It might look like a good solution if you consider riding indoors only a few times per year but still, I believe a smart trainer will give you way more opportunities to train, do proper workouts with real benefits and tracking of your performance.

And don’t forget you will miss out on the ERG mode!

Things you need with your smart tra...
Things you need with your smart trainer

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