iOS · One-time purchase · No subscription

Zone 2. Locked in.

Connect your Wahoo KICKR. Set a power target. A PID controller keeps your heart rate in Zone 2 for the entire session. Sync to Strava. Done.

Download on the App Store See how it works
9:41 Zone 2 Workout 142 BPM 168 W Target: 162W CHUNK 2 OF 4 12:34 28:20 elapsed 31:40 remaining Workout History Settings
Wahoo KICKR ERG Mode via FTMS PID Zone Targeting Strava Auto-Upload Apple Health Apple Watch HR Live Activity Dynamic Island TCX + Power Extension One-Time Purchase Wahoo KICKR ERG Mode via FTMS PID Zone Targeting Strava Auto-Upload Apple Health Apple Watch HR Live Activity Dynamic Island TCX + Power Extension One-Time Purchase
1 Hz
PID loop samples heart rate every second and adjusts resistance continuously
±30W
Automatic power adjustment range — ramps slowly, backs off fast
$0/mo
No subscription. One purchase. Your KICKR doesn't charge monthly, neither should your app
Features

Everything you need.
Nothing you don't.

01
Zone 2 tracking & ERG control
Bluetooth FTMS
Real-time heart rate monitoring with visual zone indicators. Your Wahoo KICKR resistance adjusts via the FTMS protocol — set your target power and ride.
02
PID Zone Targeting
±30W auto-adjust
A PID controller samples HR every second using a 45-second rolling average. It nudges resistance to keep you locked in zone — gradually up, faster down. Always comfortable, never jarring.
03
Strava with full data
TCX + Power extension
Workouts upload automatically with HR, power, cadence, virtual speed, distance, and accurate calories. Strava shows the full picture — not just elapsed time.
04
Apple Watch + Live Activity
HR via Watch HealthKit mirroring or pair a BLE chest strap. Stats persist on your lock screen and Dynamic Island for the whole session. A Watch complication shows current data at a glance.
05
Apple Health + workout recovery
Workouts save to Apple Health with HR and power samples. If the app interrupts mid-session, recovery mode offers to resume exactly where you left off — elapsed time and all.
App

Four screens. All you need.

9:41 Justzone2 TARGET POWER 150 W DURATION 60 min Zone Targeting Warm Up DEVICES Wahoo KICKR ● Connected Polar H10 INTEGRATIONS Apple Health S Strava Start Workout Workout History Settings
Setup
9:41 Zone 2 Workout 142 BPM 168 W Target: 162W CHUNK 2 OF 4 12:34 28:20 elapsed 31:40 remaining Workout History Settings
Workout
9:41 ‹ History Apr 18 · Zone 2 DURATION 60:12 AVG PWR 168W AVG HR 142 MAX HR 156 0 30m 60m ‹ Previous Next › Workout History Settings
Activity Detail
9:41 History Sep Oct Nov Dec Color = Power: Size = Duration Workout History Settings
Activity History
How It Works

Adaptive Zone Targeting

A PID controller monitors your heart rate every second and adjusts your KICKR's resistance — keeping you locked in Zone 2 so you can focus on anything else.

Typical 60-minute session with Zone Targeting enabled

Zone 2 0 15 min 30 min 45 min 60 min HR rising PID waits for HR to settle Cardiac drift HR slowly rises over time PID reduces power to compensate for drift
Heart Rate Power Zone 2 Band
The feedback loop
1
Measure

HR sampled every second from your Apple Watch or BLE chest strap.

2
Calculate

PID controller computes error from your Zone 2 midpoint using a 45-second rolling average.

3
Adjust

Resistance nudged gradually — ramps up slowly, backs off faster. Always comfortable.

4
Repeat

Every second, for the entire session. You keep pedalling. The app keeps you optimal.

Your fitness tracker, not just a workout tracker

As aerobic fitness improves, your body sustains more power at the same heart rate. Every session anchors to the same HR zone, making average power a direct, passive measure of progress.

  • No FTP test needed — just keep doing your sessions
  • No recovery cost — you're not exhausting yourself to measure
  • Objective progress — watts don't lie, and trends don't either

Average Zone 2 power over time

185W 175W 165W 155W Sep Oct Nov Dec Jan +23W 4 mo
Science

Why Zone 2?

It's how the pros build their aerobic engine.

  • 80/20 Polarized Training

    Elite cyclists spend 80% of training at low intensity. Zone 2 is where base fitness is built.

  • Fat Adaptation

    Train your body to burn fat as fuel. Improve metabolic flexibility and endurance capacity.

  • Mitochondrial Growth

    Zone 2 specifically targets mitochondrial biogenesis. More mitochondria = more power at threshold.

  • Sustainable & Enjoyable

    Easy effort means you can train more frequently without burnout. Build volume, not fatigue.

9:41 ‹ History Apr 18 · Zone 2 DURATION 60:12 AVG POWER 168W AVG HR 142 MAX HR 156 0 30m 60m ‹ Previous Next › Workout History Settings
Resources

Learn from the experts

Zone 2 Training

Zone 2 Training Explained

The science behind low-intensity endurance training
Zone 2 Benefits

Benefits of Zone 2

Why Zone 2 is the foundation of endurance performance
Zone 2 Guide

Complete Zone 2 Guide

How to find your Zone 2 and structure your training
Zone 2 Science

The Science of Zone 2

Mitochondrial health and fat oxidation explained
Zone 2 Tips

Zone 2 Training Tips

Practical advice for getting the most from sessions
Zone 2 for Cyclists

Zone 2 for Cyclists

Incorporating Zone 2 into your cycling training plan
Download

Start building your
aerobic base.

Join athletes who train smarter, not harder.

Download on the App Store