When to use ERG mode on Your Indoor Smart Trainer

The goal of this article is to explain what ERG mode is and how to optimize the use of this tool in your training plan.

What is ERG mode?

ERG is short for ergometer, which by definition is a machine or apparatus that measures work or energy during a period of exercise. In the cycling realm, ERG mode is a setting on smart trainers that utilizes a built-in braking system to maintain a power goal. The power will remain consistent while ERG mode is engaged by adjusting the force required to maintain a rider’s chosen cadence.

Power = Force (how hard you pedal) x Velocity (cadence)

For example, if a rider’s power goal is to hold 200 watts then the smart trainer will force the rider to hold 200 watts by applying more tension with the braking system. If the rider’s cadence drops to 70 rpm then the braking system will apply more resistance on the flywheel and increase the force needed to maintain 200 watts. If cadence is increased to 100 rpm then the braking system will reduce resistance on the flywheel thus decreasing the required force to maintain 200 watts.

The decision to use ERG mode should be based on a rider’s goals and individual training needs. This next section will discuss the potential advantages and disadvantages of using ERG mode, as well as situations when ERG mode should and should not be used.

Advantages

Easier to execute training sessions

ERG mode allows a rider to maintain their cadence within a comfortable range while the smart training dictates how hard to work. Minimal focus is required to execute the session exactly as prescribed.

Helps with distraction

It can be difficult to maintain even a casual endurance pace while riding indoors if distractions are present. Kids causing havoc, Zoom calls, or battling boredom with a movie can all lead to less wattage going to the pedals. As long as an athlete isn’t so distracted that they can maintain a steady cadence, ERG mode will help ensure the intensity doesn’t drop.

Helps push through fatigue

Endurance training frequently requires athletes to push through fatigue. Finding the motivation to continue pushing on the trainer can prove difficult for many athletes. Turning on ERG mode won’t make the intervals easier on your legs, but it will keep the power within the goal range during those moments your brain has a moment of weakness and tells you to back off just a bit.

Unload some stress

ERG mode is perfect when the goal is to simply burn some calories and unload some stress – no thinking, just pedaling. This works especially well during aerobic endurance and active recovery rides that shouldn’t require much attention anyways

Disadvantages

Not training pacing and pedaling skills

Learning how to hold a steady pace with adjustments to cadence and pedal force is a skill. Athletes that allow the smart trainer to take over this training element are missing out on valuable practice that will translate to real-world performance.

Riders new to training with power will commonly find ERG mode makes holding specific power goals during a training session much easier than trying to manually adjust every second. When outdoor performance is the top priority we recommend embracing the struggle. Accept that learning this skill is hard and failure to execute a session perfectly because the power is jumping around like crazy is totally fine, even expected.

The Spiral of Death

This happens when cadence drops too much while using ERG mode. The smart trainer will increase braking resistance quickly in an effort to keep power from dropping. Failure to quickly increase cadence will cause the resistance to continue building until it’s nearly impossible to continue pedaling (trainer tug-of-war). The only way to end the spiral of death once it’s started is to stop pedaling entirely so that ERG mode turns off. Once the braking unit has released its death grip the workout can resume as normal. ERG mode will typically turn back on once you’ve held the target power continuously for a few seconds.

Issues with Micro Intervals & Sprints

ERG mode can struggle to adjust quickly enough for short explosive efforts such as microburst intervals or sprint intervals. In addition, these short efforts are typically meant to be dynamic and not as calculated as longer steady-state efforts.

For the interval session shown in the image above, the goal was to perform a 10-minute microburst interval set. This particular set was 15-seconds “on”, with the first 2-3 seconds being a max effort sprint out of the saddle, then sit down and maintain 150% FTP or higher for the remaining time. Soft pedal for 15-seconds of recovery… repeat. ERG mode would make it difficult to have such sharp changes in power output.