Cadexa on a smart bike: a reader-confirmed Stages SB20 and Polar H10 setup

How we know this. A Cadexa rider told us in October 2026 that the app runs their StagesBike SB20 and Polar H10 without fuss, and left a public App Store review under the name “Emil” on 30 October 2026 (“Lett å koble opp, god oversikt, mange nyttige treningsprogrammer. Alt gratis”). We have not put an SB20 on our own floor yet, so the compatibility checker lists this combination as reported working, not verified. Specifications below are press-sourced, because Stages’ original SB20 pages no longer resolve.

Why a smart bike is the simplest Cadexa setup

A smart trainer needs your bike, a cassette that matches it and a thru-axle adapter. A smart bike needs a power socket. The SB20 has its own resistance unit, a 22.6 kg flywheel, buttons for virtual shifting and a crank-based power meter, and it advertises the same Bluetooth FTMS service a trainer does. To the Cadexa app it is just another FTMS machine: it reads power and cadence from Indoor Bike Data, sets target power for ERG blocks and sends gradient for routes.

Two things differ from a trainer in practice:

• Gearing is virtual. You shift with buttons and the bike changes its own ratio. In ERG mode this does not matter, the bike holds the watts; in simulation mode you shift exactly as you would on the road.
• Power comes from the cranks, not the flywheel. The SB20 measures at the crank with a claimed ±1.5 %, so the number the app shows is closer to an outdoor power meter than most trainer estimates.

Pairing

1. Power the SB20, update its firmware once with the Stages app, then close that app fully. Like trainers, the bike grants control to one app at a time.
2. In Cadexa open Devices → Trainer → Search. The SB20 appears as an FTMS device; pick it and pedal. Power and cadence show on Home.
3. Open Devices → Heart rate → Search and pick the Polar H10. The H10 supports two concurrent Bluetooth connections, so it can feed a watch and the phone at once.
4. Start a workout. Cadexa requests control, starts the machine and sends the first target; with developer mode on you can watch the acknowledgements arrive.

What the rider reported

Setup was quick, the workout library was useful, and everything was free. In the checker we have recorded power, cadence, ERG, resistance, route gradient and heart rate as reported working on iPhone with app version 1.1. If you ride the same combination, tell us what firmware the bike runs and whether anything misbehaves; the first confirmation from a second rider or from our own test moves the status to verified.

About the SB20 in 2026

Stages Cycling went through insolvency in 2024 and SB20 owners spent a long stretch without support. Giant acquired the company in 2025, support lines reopened, spare parts were manufactured again, and in October 2026 Stages launched the lighter SB200. Retailers now show the SB20 as sold out, so a new one is unlikely; a used SB20 with current firmware remains a capable machine, and the SB200 is the current-production alternative.

The heart-rate side

The Polar H10 is an ECG chest strap with Bluetooth, ANT+ and on-board memory. For Cadexa only the Bluetooth part matters, and the H10 is as uncomplicated as straps get: wet the electrodes, put it on, and it appears in the scan.

Checking your own combination

The compatibility checker shows the three layers for the SB20: what the manufacturer declared, what should work technically, and what has been reported or verified with the app.