Rowlink

Rowlink replaces the FED Fitness app for Yosuda rowers (YOSUDA-RM-*). Open it in Chrome or Edge on Android, Windows, macOS, ChromeOS or Linux, wake the rower with a stroke, and tap Connect rower.

It also fixes the jumpy numbers other apps show. The rower's own pace and power readings swing 2× from one stroke to the next, so Rowlink works them out from the rower's distance and stroke counters instead.

Features

Live dashboard

• Pace, time, distance, stroke rate, power, knob level and calories, sized to read from the seat
• Rolling 3-minute chart of pace and stroke rate
• Stroke-rate gauge with the target range marked, and a stroke pacer to follow (optional metronome click)
• Tiles turn green when you're on target and amber when you drift off
• Pauses by itself when you stop rowing, and reconnects by itself if Bluetooth drops

Guided workouts, hands-free

• Intervals, benchmarks (500 m, 2000 m, 20 min), steady rows, a pyramid, and 27 classes modelled on the FED app's rower classes
• A countdown and a big "Set knob to 8" prompt before each resistance change. The app assumes you made the change, so you never have to reach for the phone mid-row
• Want a different knob for a step? Tap − / +. The next step switches back to the workout's level, with the usual prompt
• Pace targets scale to your reference pace: set it in Settings, or row a benchmark
• Copy any workout and edit it, or build your own from row and rest segments
• The workouts you rowed last sit at the top of the list, ready to start again
• Share your workouts as a file anyone can import, or suggest one on GitHub to be added for everyone

Full screen

• One tap (on the icon in the header, or the button under the dashboard) fills the screen with the workout and the numbers. On Android it also turns to landscape, even with rotation locked

History and export

• Every row of 20 m or more is saved in the browser, including sessions cut short by a closed tab or dead battery
• Charts of pace, stroke rate, power and knob, with the workout's target bands, plus how much of each step you spent on target
• Export to FIT (Garmin Connect, Strava), TCX, CSV or JSON. Back up and restore all history as one JSON file

Private

• Sessions, workouts and settings stay in your browser. No account, no tracking

Screenshots

Full screen on a phone in landscape, the way it's meant to be used on a rower mount:

Before each resistance change, a prompt counts you down to it:

Phone in portrait: the live dashboard, and the workouts list with each workout's shape and length.

A saved session, with how closely you hit each step's targets:

Screenshots use the built-in simulator, which the connect screen offers when no rower is nearby.

Run it locally

python3 web/serve.py

Then open http://localhost:8080/web/ in Chrome. On Linux, Web Bluetooth may need chrome://flags/#enable-web-bluetooth. No rower nearby? Use Simulator, or Replay a capture of a real session, on the connect screen.

Tests

cd web && npm install && npm test

Project layout

App	web/: plain HTML/JS, no build step (details)
Design notes	PLAN.md: protocol findings, data pipeline, decisions
Recordings	captures/: raw Bluetooth sessions from the real rower, used by the tests and the Replay feature

Not supported

iOS (no Web Bluetooth in any iOS browser), Firefox and Safari.