Derny reads your heart rate, power, and cadence in real time and adjusts every target on the fly — a coach in the room, not a script on a screen.
When your heart rate climbs past its ceiling, Derny automatically lowers the intensity to bring you back — then builds again as you recover. No buttons, all ride.
Most riders never touch a setting — pick a ready-made adaptive workout, press start, and Derny adjusts to your body as you go. But if you like control, the door's right there: open the editor and write your own rules, trigger by trigger.
“If my heart rate goes above 160 for 10 seconds, drop the target by 5 watts — then hold for 30.”
You can build a rule like that by hand — or just let Derny's presets do it for you.
Effort holds no matter what. Your heart rate redlines — the workout never notices.
Effort eases as you tire, so your heart rate settles right where it should.
Every beta rider gets the whole app — every workout, every adaptive rule, no feature held back.
Any FTMS smart trainer, whatever badge is on it — FTMS is the open Bluetooth standard nearly every modern trainer speaks. Derny drives power and resistance straight over Bluetooth, screen-locked, all ride. Pair any Bluetooth heart-rate strap alongside it.
Connect your account once and every finished ride uploads itself — power, heart rate, cadence, the lot. No exporting, no emailing files to yourself, nothing to remember after you unclip.
Build and edit workouts by chatting with your own Claude or ChatGPT through a real, OAuth-secured connection. “Give me a 60-minute sweet-spot session that backs off if my HR climbs.” Done.
Guest-first and offline-first — it works fully signed-out with your data on your device. Sign in only if you want cloud backup and sync. No ads, no tracking, ever.
FTMS is the open Bluetooth standard for smart trainers, and it's what Derny talks — so every trainer that supports it is driven the same way, with no partnership and no per-brand hacks. Riding something that isn't listed? If it pairs as a controllable smart trainer over Bluetooth, it almost certainly works.
See full trainer compatibility →Big, honest numbers — target vs. actual power, heart rate, cadence, block progress — and a full post-ride analysis when you're done.
The beta is live on iPhone via TestFlight, and opening up on Android. Pick your phone, connect your trainer, and feel a workout adapt to you for the first time.