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Compare
These are all good apps, and they solve different problems. The short version: Zwift, TrainerRoad and Wahoo SYSTM run your trainer to target watts and adapt your plan between workouts. Derny changes the target inside the workout, second by second, from your heart rate, and it does the same on a treadmill or an elliptical.
At a glance
| Inside a workout | Between workouts | Treadmill | Price (US) | |
|---|---|---|---|---|
| Derny | Moves watts, belt speed or elliptical target from live heart rate | No training plan yet | Sets belt speed on FTMS treadmills that accept it | Free in beta |
| Zwift | ERG holds the workout’s target watts | Zwift Coach adjusts your plan (Zwift Plus) | Reads speed from a treadmill or footpod | $19.99/mo; Plus $29.99/mo |
| TrainerRoad | ERG holds the workout’s target watts | Adaptive Training adjusts future workouts | No treadmill control | $21.99/mo or $209.99/yr |
| Wahoo SYSTM | ERG holds targets set from your power profile | Plans scale to your tested ability | No treadmill speed control found | In Wahoo App Pro, $17.99/mo |
Prices are US list prices before tax, as published in November 2026. Check each company’s site for current pricing; sources are at the bottom of this page.
The difference
TrainerRoad’s Adaptive Training and Zwift Coach look at how your completed workouts went and change what comes next. That’s valuable, but once a workout starts, the targets are fixed watts. If you slept badly and your heart rate is ten beats higher than usual, the trainer still holds the same power.
Derny works inside the session. It reads your heart rate every second, and when it climbs past where the workout wants it, the target comes down. When you recover, it builds again. On a treadmill, the same idea moves the belt speed, never above a max you choose.
Derny isn’t the only app with a heart-rate mode. TrainerDay, for example, has one for trainers. What Derny adds is ready-made workouts built around it, the same approach on trainers, treadmills and ellipticals, and a rule editor if you want to write your own.
Choose by what you want
If you want virtual worlds, group rides and racing, and you’re happy training to power.
If you want a structured, power-based plan for a target event, with the plan adjusted around your results.
If you want video-led sessions and a plan built from a full power profile test.
If you want each workout to respond to how your body is doing today, you train by heart rate, or you train on a treadmill or elliptical as well as a bike.
They aren’t exclusive. Plenty of people ride Zwift for fun and use a heart-rate-led session on easy days. Derny uploads every workout to Strava, so your training log stays in one place.
Sources
Checked 7 November 2026. Spotted something out of date? Email [email protected] and it gets fixed.
Questions people ask
Not as of November 2026. Zwift’s ERG mode holds the workout’s target watts, and Zwift Coach adapts the plan between workouts. Derny changes the target inside the workout from your live heart rate.
No. TrainerRoad’s Adaptive Training adjusts your future workouts based on how completed ones went. Derny adjusts the workout you’re doing, second by second, from your heart rate.
Derny is free while in beta, on iPhone and Android. It runs heart-rate-led workouts on FTMS smart trainers, treadmills and ellipticals, without virtual worlds.
Derny sets the belt speed from your heart rate on FTMS treadmills that accept speed control from an app, never above a max speed you choose. Zwift reads treadmill speed but doesn’t set it.
Try it
The beta is live on iPhone through TestFlight and on Android through Google Play. Your invite arrives by email.