Garmin Speed Sensor 2 and Cadence Sensor 2: Compact and Reliable

Garmin's Speed Sensor 2 and Cadence Sensor 2 are second-generation versions of the company's hub-mounted speed sensor and crank-arm-mounted cadence sensor. The original sensors launched in 2012 and have been bestsellers ever since.

What changed in v2

The v2 sensors add dual ANT+/Bluetooth transmission (the original was ANT+ only). This means the sensors can broadcast to a head unit (ANT+) and a phone (Bluetooth) simultaneously. For riders who want both a bike computer and a phone app tracking their ride, this is a real improvement.

Speed sensor accuracy

The Speed Sensor 2 attaches to the wheel hub and counts wheel revolutions. With proper calibration (inputting your tire circumference), accuracy is 卤1% vs. GPS-based speed. This is more accurate than GPS for steady-state riding and works indoors on a trainer.

Cadence sensor accuracy

The Cadence Sensor 2 attaches to the crank arm and detects each pedal stroke via accelerometer. Accuracy is 卤1 RPM vs. power-meter-derived cadence. For most riders, this is excellent.

The verdict

Garmin's Speed Sensor 2 and Cadence Sensor 2 are the best-of-class for the price ($39 each, or $75 for the bundle). The dual ANT+/Bluetooth transmission, year-long battery, and proven reliability make them the right choice for most riders. If you already have a power meter with cadence, the cadence sensor is redundant. If you have a smart trainer with virtual cadence, both are redundant. For wheel-on trainers or older bikes without electronics, these sensors are essential.