Indoor cycling offers a different experience from riding outdoors and enables you to undertake training that may not be possible otherwise, such as climbing mountains which replicates long climbing efforts.
Very few of us are fortunate enough to be situated near Alpe d’Huez though, but with Zwifts replica, Alpe du Zwift, we can enjoy the legendary climb no matter our geographical location.
Features like this now allow cyclists worldwide to train more effectively in the winter months, and there are more training tools on offer than ever before.
The best smart trainers and platforms are stacked with features, yet one of the most useful, and commonly used features remains one of the least understood, and that is ERG mode.
Load a training session or ride, set the deisred power output, and as long as you keep pealling at the right candence ERG mode will sort it, right?
It's indoor cycling week at Cyclingnews, we have highlight the benefits and broken down the pros and cons regarding ERG mode so you are better equipped to know when to use it and when to leave it off.
What Is ERG Mode and How Does It Work?
ERG mode is a smart trainer feature that enables riders to train at a prescribed power output and makes structured workouts and interval sessions easier to execute consistently.
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ERG mode automatically adjusts the resistance of a compatible smart trainer to help you maintain a target power output. When following a structured workout on a virtual training platform such as Zwift or TrainingPeaks Virtual, the trainer continually adjusts resistance to match the power target prescribed for each interval.
This means you can focus on your cadence and completing the interval rather than manually changing gears and concentrating on maintaining your target power, as you would when riding outdoors.
(Image credit: Zwift)
When Should You Use ERG Mode?
ERG mode is particularly useful during structured training sessions where you need to maintain a specific power output for a set duration. It allows you to focus on executing each interval while your smart trainer manages the resistance.
It's especially useful for longer threshold and VO₂ max intervals, where maintaining a consistent effort can be challenging. It can also help you keep recovery intervals at the prescribed intensity.
However, ERG mode isn't always the best choice, particularly for short, explosive efforts or workouts where there is less control.
The way ERG mode works can vary between platforms. For example, Zwift uses ERG mode during structured workouts, while TrainingPeaks Virtual also allows you to enable it during free riding to maintain a defined power target. In both cases, the smart trainer automatically adjusts resistance to help you achieve the desired output.
How to Use ERG Mode
ERG mode is relatively simple to use, particularly when following a structured workout.
Zwift offers a library of structured sessions and supports the functionality to import predefined sessions from training apps like TrainingPeaks or Vekta. These workouts typically prescribe interval intensities relative to your Functional Threshold Power (FTP).
FTP is an estimate of the highest power you can sustain in a steady state near your lactate threshold.
It is commonly used to set training zones and calculate workout targets, so an accurate FTP setting helps ensure that your intervals are appropriately challenging.
To get started, select the workout session and connect a compatible smart trainer. Once the workout begins, ERG mode is applied by default. The trainer will adjust resistance to help achieve the prescribed power for each interval.
If the workout is too difficult or easy, you can adjust this. In Zwift, for example, the difficulty can be manually adjusted using the workout intensity controls in the game or on the Zwift Companion app.
Remember that ERG mode doesn't remove the need to manage your effort. You still need to choose a sustainable cadence and pedal consistently to reach and maintain the target power. If an interval becomes unmanageable, reduce the workout intensity or switch ERG mode off temporarily to recover.
(Image credit: Rouvy)
Things to Watch Out For
Although ERG mode makes structured training easier to manage, there are a couple of common pitfalls to be aware of.
1. The Spiral of Death
The Spiral of Death occurs when your cadence drops significantly during an interval. The trainer may increase resistance to help reach the prescribed power. Consequently, pedalling becomes harder and harder, causing your cadence to fall further and creating this cycle, which is impossible to sustain.
To avoid this, you need to ensure you are able to sustain a suitable cadence. If you find yourself struggling, reduce the workout intensity or temporarily disable ERG mode whilst you reset and bring the power back up in a manageable way.
2. Choosing the Wrong Intensity
If your workout targets are too high, ERG mode can make achieving the interval unmanageable.
Conversely, if the targets are too low, you won't have the necessary stimulus, and you will find yourself spinning your legs furiously without really any training benefits.
Check that your FTP is set appropriately and adjust the workout intensity if necessary. The goal goal is to complete the prescribed effort at a sustainable level, not simply to survive every interval.
(Image credit: Elite)
Benefits of ERG Mode
ERG mode offers several advantages for indoor training:
Consistent power output: Ensures you stay close to the prescribed power throughout each interval. Useful for threshold and VO₂ workouts.
Fewer distractions: You can focus on technique, cadence, and effort without having to adjust power.
Controlled training intensity: It makes it easier to follow structured workouts and complete intervals at the intended intensity.
Simpler recovery intervals: Helps with riding at a consistent pace; if you are doing a recovery ride, you can set the resistance to a certain power and keep it there.
Interval training outdoors can be challenging because of traffic, terrain, and changing conditions. A smart trainer operating in ERG mode removes many of these distractions, allowing you to concentrate on your workout.
ERG mode is a training tool rather than a shortcut to better fitness. The training stimulus itself helps build strength and endurance; ERG mode simply helps you deliver that stimulus more consistently.
In essence, the smart trainer puts you in the hurt zone and helps keep you there when the workout calls for it.
Should You Use ERG Mode?
ERG mode is well worth trying if you don't already take advantage of it. It's particularly useful for structured workouts, longer intervals, and sessions where hitting a prescribed power target is important.
ERG mode can make indoor training simpler and more consistent, helping you get more out of your sessions without taking away the need to understand your effort.
Ultimately, the best approach depends on your training goals. Use ERG mode when you want to focus on completing controlled intervals, and switch it off when you want more freedom to manage your own power.
