Smart Bike Trainer

Overview

A direct-drive smart trainer turns a normal bicycle into a stationary, app-controlled exercise machine. The rider removes the rear wheel and bolts the bike's chain directly onto a cassette on the trainer, so the bike's own chain drives a heavy flywheel braked by an electromagnetic unit. The trainer measures how hard the rider is pedaling, broadcasts that power to training apps, and accepts commands back to vary resistance, simulating climbs, drafting, or a structured workout while the bike stays in one place.

The unit is built on a steel Frame & Base with folding legs for stability. Its Drive Unit carries the cassette and couples it by belt to an inertia flywheel, while the Electromagnetic Resistance Unit applies controllable braking force. A Control Board runs the control loop, a Sensor Pack measures what the rider is doing, and a Connectivity Module links to apps over ANT+ and Bluetooth.

How it works

Pedaling spins the cassette, which drives the flywheel through a belt; the flywheel's mass gives the road-like inertia of coasting and accelerating. Braking torque comes from the Electromagnetic Resistance Unit, an electromagnetic motor-brake whose coils, when energized by the Control Board, induce eddy currents in a permanent-magnet rotor, more current, more drag, and can even drive the flywheel to simulate descents. The Sensor Pack reads true power from a strain-gauge torque sensor on the drive shaft rather than estimating it, hitting ±1% accuracy, alongside a Hall speed pickup and a cadence sensor. The Connectivity Module streams power, speed, and cadence to apps and accepts resistance targets back: in ERG mode it holds a set wattage regardless of gear, and in simulation mode it matches resistance to a virtual course's gradient. The Axle Adapter Kit lets road and mountain frames with different axle standards bolt to the same trainer.