S-Bike Training Hub MCP server

S-Bike Training Hub

Turn a budget smart bike into a full training setup: offline 3D routes, virtual hills and gears, auto-shifting, ERG workouts, a phone handlebar remote, and a training-load model that covers every sport you do, not just the bike. It runs entirely on your Mac, with no subscription and no cloud.

It was built for, and has only been tested on, the Merach S29. Other smart bikes that speak Bluetooth FTMS may work, but we couldn't test them (see Other bikes).

Merach S29 owner? The problems this was built to fix:

• Only one thing can connect to the bike at a time, so your watch can't record power and cadence while Zwift or Kinomap is connected. The hub holds the one connection and shares it with both.
• Hills didn't change the resistance in Zwift or Kinomap on our S29: it ignored the apps' hill commands. The hub turns the grade into resistance itself, eased in smoothly.
• No gears, and no virtual shifting. The hub adds virtual gears and auto-shifting that keeps your cadence in a band, plus big shift buttons on your phone.
• ERG that grinds you to a stop when you tire. The hub's ERG works in zones around the target, backs off when your cadence falls, and pauses and resumes the workout.
• No subscription needed: routes, workouts and training load all run on your Mac.

Newer S29 units, and the S29R2 (2026), may handle hills in Zwift and Kinomap on their own; we haven't tested them.

 

What it does

The S29 only accepts one Bluetooth connection, and it ignores the "hill" commands that training apps send. The hub sits in the middle: it holds the single connection to the bike, and then:

• Shares the bike. It re-advertises the bike as a new device ("SBike Hub"), so a watch (power + cadence) and a training app can connect at the same time.
• Makes hills real. Grades from a route or a training app become resistance, eased in smoothly, with virtual gears on top.
• Auto-shifts. It keeps your cadence in a band (65–80 rpm by default), shifting sooner the harder you spin. With a daily focus it also steers your watts into a range: easy but still productive. A climbing mode handles low-cadence standing efforts.
• Computes virtual speed from watts, weight and grade, so climbs feel like climbs.
• Runs ERG workouts. It holds a target wattage whatever your cadence. In a workout it works in zones around each block's target instead of chasing every watt: green (90–120%) never shifts, yellow (80–90% / 120–140%) is still on the road and shifts after 2 minutes, red after 30 seconds, black after 8. Before it shifts, it checks where the next gear would land, and it won't shift you off the road. FTP tests and Kinomap keep tight control.
• Pauses and resumes. The workout clock only runs while you pedal with the bike connected: stop and it pauses by itself, or tap ⏸. If a workout stops before it's done (you tapped End, the page reloaded, the bridge restarted), the Coach page and the game view offer Resume for the rest of the day, at the same block and second. The pieces of a day's ride count as one session.

On top of that:

Shortened. The full README is on GitHub.