What is a smart trainer?

A beginner's guide to virtual cycling trainers that bring indoor training apps to life

Simon von Bromley / Immediate Media

Published: November 8, 2017 at 3:00 pm

If you've heard your riding mates carrying on about Zwift and smart trainers but you have no idea what they're talking about, let us help.

A smart trainer is a tool you mount your bike on that offers resistance like a normal trainer, but with the added benefit of allowing the resistance to be controlled by cycling apps such as Zwift.

What's the point of a smart trainer?

The boom of indoor cycling apps such as TrainerRoad, Zwift, RGT Cycling and The Sufferfest have created a cottage industry of smart trainers for the simple reason that the tool makes indoor cycling so much more engaging.

When riding a virtual course on a smart trainer, if you begin to climb a hill the resistance ramps up and you have to pedal harder (or change to an easier gear!), just like when riding outdoors. This works with real-life POV video on apps such as Rouvy and FulGaz, as well as digital worlds like Zwift.

Cyclists wearing the BikeRadar kit on Zwift
With a smart trainer, your pedal power drives apps like Zwift, which can in turn control the resistance for hills, drafts and structured workouts. - Zwift

When doing group rides or races on Zwift, the resistance gets easier when you are riding in a group, simulating a draft, and harder when you are alone in the wind.

Similarly, when doing structured workouts, a smart trainer automatically sets resistance to the exact prescribed wattage, so you don't have to worry about gauging or pacing your effort.

So, there are key reasons to use a smart trainer: to make indoor cycling much more fun and more productive.

How a smart trainer works

Training on a smart trainer
Smart trainers are equipped with built-in power meters. The latest direct-drive trainers replace the rear wheel of the bike. - Simon Bromley / Immediate Media

Smart trainers communicate on ANT and Bluetooth. ANT is cycling's standard wireless frequency, so most bike computers, heart-rate monitors, power meters, speed/cadence sensors and such work on ANT . Bluetooth is native on smartphones and many tablets and computers.

You can 'drive' a smart trainer with a newer bike computer, such as a Garmin Edge 530 or a Wahoo Elemnt Bolt. With this method, you can set the resistance at a particular wattage, complete a workout or ride a previous course.

What is a lot more interesting for most folks is to 'drive' the smart trainer with a cycling app.

With this method, you load the app on your smartphone, tablet or computer, then connect it to your smart trainer via Bluetooth or ANT .

I recommend using Bluetooth for this connection because it is often more stable and it doesn't require an ANT dongle. (The latest Samsung Galaxy has native ANT , but most phones and computers do not.)

With most smart trainers, you need to plug them in — another difference from a standard trainer. How smart trainers generate resistance varies by model, with many using a combination of a flywheel (like a standard trainer for good road feel), magnetic resistance and an electronic motor/brake.

What you need to use a smart trainer

To get in the virtual cycling game, you need:

  • A computer, tablet or smartphone with native Bluetooth or an ANT USB dongle
  • Good WiFi
  • A smart trainer
  • Your bike
  • A big fan!

Two types of smart trainers

Smart trainers fall roughly into two categories: wheel-on designs and direct-drive models.

Wheel-on smart trainers look most similar to a normal trainer, where you clamp your bike at the rear axle and then tighten a drum against your rear tire for resistance.

This design is relatively lighter (sub 40lb / 18kg), relatively cheaper (models start at £279 / $349) and relatively easier to store, as the legs often fold up.

Saris M2 smart turbo trainer
Wheel-on smart trainers are generally lighter and cheaper than direct-drive models. - Simon Bromley / Immediate Media

On the downside, wheel-on smart trainers require calibration each time you put your bike on them, which includes a 10-minute warm-up. And often, the power accuracy isn't quite as good as on a direct-drive model.

Saris H3
Direct-drive smart trainers can offer better power accuracy and a more stable platform, but usually weigh and cost more than wheel-on models. - Simon Bromley / Immediate Media

Direct-drive smart trainers, like the Tacx Neo 2T Smart and the Elite Suito, are sturdy units that effectively replace your rear wheel. After installing a cassette, you pop off your wheel and mount the trainer on the direct-drive trainer.

Benefits of this design include stability, accurate power measurement and no need to warm-up before calibrating. The downsides? Cost and weight. Prices start at £699 / $899 and most of them weigh about 47lb / 21.3kg.

wahoo kickr bike
Smart indoor bikes are targeted at cyclists looking to squeeze every last watt out of their indoor cycling. - Tom Marvin / Immediate Media

Lastly, For those who take their indoor cycling very seriously, there is now also a wide range of smart indoor bikes. It's fair to say they cost a lot, weigh much more and take up a greater amount of space, but they do offer advantages over standard smart trainers which the dedicated indoor cyclist will appreciate.

Which smart trainer should I buy?

Good question! Our expert testers have reviewed a wide range of smart trainers and have compiled a list of the best ones on the market right now.