watty

Indoor cycling in the terminal. watty controls an FTMS smart trainer in ERG mode, plays .zwo workouts, reads a BLE heart-rate strap and records every ride.

Features

• ERG workouts from .zwo files: steady, ramps, intervals and cadence targets, with a soft start and a countdown before each segment change.
• Live ride screen: power, target, heart rate (colored by zone), cadence, time left and the workout profile with your actual power drawn over it.
• Auto-pause when you stop pedaling, +/- to adjust intensity, and a hint to back off when heart rate drifts too high on an endurance segment.
• Recording to CSV and TCX. An interrupted ride (crash, quit) can be resumed where it stopped.
• Strava upload of each saved ride, or any past ride from the calendar.
• Calendar of past rides and planned workouts, with per-ride stats (NP, IF, TSS) and charts.
• Simulator to try everything without a trainer.

Install

Needs Linux with BlueZ and a Rust toolchain.

cargo build --release
./target/release/watty

Start a ride with Enter on the Workouts tab, or s for a test ride on the simulator. Missing FTP or weight takes you to Settings first; the trainer and HR sensor are picked from a device scan.

Ramp test is a workout like any other, so it can be planned in the calendar too: 5 min warmup, then ERG steps from 100 W, +20 W every minute, until the cadence stays below 55 rpm for 5 s. FTP is 75% of the best minute; press f at the end to save it. <RampTest Warmup="300"/> as the last element of any .zwo file does the same.

Keys

Ride
space	start / pause
+ -	intensity ±5%
n	next segment
q	quit (save or discard)

Activities
Enter	ride details
a / d	plan / unplan a workout
p	ride the planned workout
r	resume an interrupted ride
u	upload a ride to Strava
[ ] / t	change month / today

Command line

watty scan                                   # find BLE devices
watty ride workouts/sweet_spot_3x10.zwo      # ride without the home screen
watty ride workouts/test_short.zwo --sim --speed 10
watty monitor --trainer <ADDR> --hr <ADDR>   # read-only data
watty erg --trainer <ADDR> --watts 100       # fixed ERG target
watty export ~/.local/share/watty/rides/<ride>.csv
watty strava connect                         # log in to Strava (also in Settings)
watty strava upload <ride>.csv

Strava

Connect with Enter on Strava in Settings. Saved rides are then uploaded as trainer rides when they end (turn off with Upload to Strava); simulator rides never are.

watty needs your own Strava API app with localhost as the callback domain. Pass its credentials via WATTY_STRAVA_CLIENT_ID / WATTY_STRAVA_CLIENT_SECRET, or strava_client_id / strava_client_secret in config.toml. A new Strava app only accepts its owner until Strava raises its athlete limit.

Files

~/.config/watty/config.toml	settings (also editable in the Settings tab)
~/.local/share/watty/workouts/	.zwo workouts, seeded with examples
~/.local/share/watty/rides/	recorded rides (CSV + TCX); simulator rides in test/
~/.local/share/watty/plan.toml	planned workouts
~/.local/share/watty/strava.json	Strava tokens
~/.local/share/watty/watty.log	log

The plan can be edited by hand:

[[workout]]
date = 2026-10-16
file = "sweet_spot_3x10.zwo"   # relative to the workouts folder, or absolute