justzone2

Most indoor cycling apps hold your power. JustZone2 holds your heart rate.

Set your zone, start pedalling, and the app takes over. It reads your heart rate every second and continuously adjusts your trainer's resistance to keep you exactly where you meant to be — no watching the numbers, no reaching for the dial halfway through. Just the right effort, for the whole ride.

ADAPTIVE ZONE TARGETING • A PID controller trims trainer resistance in real time to hold your heart rate in Zone 2 • You choose where you ride within Zone 2 — the upper part by default, where steady Zone 2 rides are meant to sit • Handles cardiac drift automatically — as you tire and your heart rate climbs, the power eases back to match • Optional warm-up and cool-down phases • Prefer to ride to a number? Run it as a straightforward fixed-power ERG session instead

AND, WHEN YOU WANT IT, INTERVALS • An optional Interval Builder for your hard days, switched on in Settings • Set the number of intervals, their length and power, and the recovery power in between • Ride in sets, with a longer recovery between them, for sessions like Rønnestad's 3 × 13 × 30/15s • Ridden in ERG mode, with a countdown to every interval and the session's shape on screen • See each session's weighted average power, a better guide to how hard it will feel than plain average power • Interval rides upload to Strava under their own name and stay out of your Zone 2 progress charts

WORKS WITH YOUR GEAR • Any smart trainer supporting the FTMS Bluetooth standard, including the Wahoo KICKR range • Heart rate from an Apple Watch, a Bluetooth chest strap, an optical arm band, or AirPods Pro 3 • Universal — iPhone, iPad and Apple Watch, with a Watch complication for a glance mid-ride

YOUR DATA, WHERE YOU WANT IT • One-tap upload to Strava with power, heart rate, cadence, distance and calories • Saves to Apple Health as a full workout • Live Activity keeps your stats on the Lock Screen and in the Dynamic Island • Workout history with charts, so you can watch the aerobic base actually build

BUILT TO GET OUT OF THE WAY • Large, readable metrics you can see from the bars • No ads, no upsells, nothing to sign up for • No subscription — one purchase, yours for good • Interrupted mid-session? It picks up exactly where you left off

WHY ZONE 2 Easy aerobic work is what builds the engine: more mitochondria, more capillaries, better fat metabolism, and a foundation broad enough to carry everything you stack on top. It is the bulk of what elite endurance athletes actually do all year.

Understanding that has never been the hard part. Holding the discipline to ride easy enough, for long enough, is the hard part — and that is precisely the bit JustZone2 takes off your hands.

MADE FOR • Cyclists building an aerobic base through the winter • Athletes who want recovery days to stay genuinely easy • Anyone after structured indoor training without a games engine attached

REQUIREMENTS A smart trainer that supports FTMS, and a heart-rate source — Apple Watch, chest strap, optical arm band or AirPods Pro 3.

Set your zone once. Every ride after that, just press start.

Discovery signals