Indoor cycling for macOS and your phone
You bought the smart trainer. You bought the bike. FreeGaz drives them in ERG, level, slope or heart-rate mode, runs structured workouts and FTP tests, rides real roads, and keeps every second on your Mac as a FIT file. It costs nothing, now or later.
v0.5.0 pre-release · Apple Silicon · Free and open source (MIT)
No Premium tier, no annual plan with the cancel button four menus deep, and no "your trial has ended" email on the morning of your FTP test. The only thing it charges is your legs.
A quick tour
One big button, four choices: ride for time, free ride, a route or a workout. Your trainer and heart-rate status sit on top, so you know before you start.
Ride for time holds your watts from easy to sweet spot for 20 to 90 minutes. No forty-tab dashboard to decode before your warm-up.
Your coach bikes next to you at your target. Ease off and they ride away and tell you about it. Push and you drop them, which is the best feeling in indoor cycling.
The big numbers stay big: interval, target and power, with the workout chart filling in as you go.
From a calm Zen master to a drill sergeant, a disappointed dad and a data nerd, plus two famous podium voices doing their best impressions.
Spice runs from gentle to feral. Profanity goes from Clean to Mild to Unhinged. Unhinged means it. Your body, weight and health are never joke material, and if your heart rate looks wrong every coach turns supportive.
Every workout is drawn as its power profile at your FTP, on three shelves: FreeGaz's own, your custom ones, and a training plan you put in order.
There's an FTP test too: 20-minute, 8-minute or ramp. A valid result saves your FTP automatically, with one-click undo.
Eight rude workouts where the power chart is the joke. The Bird is four knuckles at threshold and a middle finger at 150 % FTP. Mount Stupid is the Dunning-Kruger curve. Stairway to Hell has no landing. Liar Liar says "last one" seven times.
The other four have names that don't belong on a homepage.
Drag blocks, resize them, type intervals.icu text, or describe it and let the AI write it. Live TSS, IF and zone totals at your FTP.
Import .zwo, .mrc and .erg, and export straight into Zwift's custom workouts.
Import a GPX and the trainer climbs when the road does. Race a ghost of your last attempt if you're feeling brave.
Or turn on Journeys and ride somewhere real: Land's End to John o' Groats, the Danube, Route 66 or Tokyo to Hiroshima. Each ride picks up where the last one stopped, and lands on Strava with a map.
Everything it does
.zwo, .mrc, .ergTested on a Wahoo KICKR and a heart-rate strap. Everything else follows the Bluetooth specs and is tested against a simulator.
Your data
Everything lives on your Mac: the ride database, plus a FIT file per ride in ~/Documents/FreeGaz/Rides. Point that folder at iCloud Drive for free sync.
Nothing leaves the machine unless you connect Strava or intervals.icu, turn on an AI provider, or send a bug report. API keys are encrypted with your macOS Keychain.
On your phone
Open FreeGaz in your phone's browser and add it to your home screen. It gets its own icon, opens full screen and works offline, which is handy, because the pain cave never has Wi-Fi.
The full experience, trainer included.
Everything except Bluetooth: Apple doesn't let any iPhone browser talk to trainers or straps.
Download
Needs a Mac with Apple Silicon and Bluetooth.
Needs Node 24 or later.
git clone https://github.com/raytfitzgerald/FreeGaz
cd FreeGaz
npm install
npm run devNo trainer handy? FREEGAZ_SIM=1 npm run dev runs it against a simulated KICKR and heart-rate strap.
FreeGaz is free and always will be. If it saved you a subscription, you can put a little toward the developer's next bike. Totally optional, and it unlocks nothing.