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- How to use ERG mode in Workouts

If you do a workout with a smart trainer, you may have the option to use ERG mode. ERG mode is available on select smart trainers and sets the resistance to a specific wattage target based on your cadence instead of basing it on the course gradient (SIM mode).

What's this mean?

As an example, let's pretend you're going into a workout interval with a target of 150w. Here are the key differences:

  • The resistance will change based on your wattage target and cadence: If you're going at 60 RPM (revolutions per minute), the resistance is going to ramp up so that your 60 RPM generate 150w. Alternatively, if you spin up your cadence to 90 RPM, you'll feel the resistance drop so that you're still putting out 150w. It may take your trainer time to adjust, so it's best to spin at a consistent cadence or slowly change your RPM.
  • No shifting: Since your trainer is automatically adjusting your resistance based on your cadence/wattage target, you don't need shift your gears. Get into a neutral gearing for your chain and pedal away!
  • Wattage target vs course gradient: When you're going up or down a hill, you won't feel the resistance change based on the gradient, only the wattage target. Your speed in Zwift will still be calculated based on your wattage, and in that sense, it's like riding a classic trainer.

In summary, ERG mode is only available in workouts, just like SIM mode is only available in free ride. In ERG mode, resistance doesn't change with the course - it changes with wattage targets.

How to use ERG mode 

  1. If ERG mode is available on your smart trainer, you'll see a checkbox with the "Use ERG mode option" on the workout selection screen. Click the box.
  2. Pick your workout and join the world.
  3. Get your bike into a gear that'll reduce wear on your chain/keep it straight.
  4. Start pedaling at a cadence you're comfortable with. Just be careful if you have high wattage targets on your workout - you might need to kick up your RPM! 


Q: The resistance increased too much, and I couldn't pedal!
A: This is typically for one of two reasons: your cadence was too low entering a high wattage interval or your FTP is set too high. You may want to try keeping your cadence > 90 RPM so that the resistance for your trainer doesn't increase dramatically when you enter an interval with a high wattage target. 
Alternatively, if your FTP is set too high, the wattage target may simply not be feasible at your current fitness level. If you haven't completed one of the FTP test workouts, do that first.
Q: The resistance on my smart trainer is changing too slowly.
A: While in ERG mode, Zwift sends commands to all trainers in the same manner; it's up to that trainer to interpret how it changes resistance, and some trainers adjust faster than others.
Q: I changed gears, but I still couldn't hit the target wattage. 
A: You shouldn't be changing gears while using ERG mode - unless you're doing an FTP test.
Q: I can't get enough resistance during the actual FTP test
A: The actual FTP test portion holds a flat resistance, so you'll need to change your gears to increase/decrease wattage, like you would on a regular ride.
Q: I missed my interval target/stopped pedaling, and ERG mode was disabled. Why? How do I turn it back on? 
A: If Zwift senses that you're failing an interval (i.e. you can't pedal because the resistance is too high), ERG mode will automatically be disabled so that you can continue to spin for the remainder of the interval. After it's disabled, your resistance will not change based on the wattage target or the course, but be set as if you're riding on a flat road.
If you resume pedaling at a wattage that's close to the target wattage level, certain smart trainers will display a message about holding your wattage to re-enable ERG. Simply continue pedaling, and ERG mode will re-engage for the target wattage. We're constantly expanding the number of trainers that include this feature, so if your trainer doesn't allow this, stay tuned!
Here's a list of trainer with the ERG resume feature and which connection it works over (this is a work in progress):
 Trainer Name   ANT+?   BLE?   USB 
Tacx Vortex N Y
Tacx NEO Y Y
 Computrainer - - Y


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