The Polar Power Output Sensor from Polar is one of the most accurate measures of cycling power available on the market. It measures power directly from the chain. It uses chain tension, bike speed, pedal cadence, and chain speed to calculate the overall power figure. This unit is WIRED and it requires the cabling of a wire from bottom bracket to handlebar mount. The speed sensor is part of the Power bar. Speed is taken off the BACK wheel speed magnet, this is ideal for Turbo Trainers and similar as
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