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Polar Power Kits
The new Polar Power Output Kit is designed for use with the Polar S-625X, S-720, S-725 and S-810 Heart Rate Monitors.
Combine the benefits of training with heart rate and wattage. The ideal training tool for cyclists - measures your right and left pedaling and overall efficiency. Data can be displayed on your PC for the evaluation. Easily adapts to any bicycle - doesn't require any wheel or hub changes. Weighs less than 1/2 pound.
How Does this System Measure Power?
The Power Output Sensor measures power direct from the chain, unlike other models that use the crank or hub. This precision system combines measures from two key factors:
Chain Tension using a sensor on the chain stay
Chain Speed using a sensor on the rear pulley
Power = Chain Tension x Chain Speed
All of the drive force of the bike is transmitted through the chain, allowing Power Output Sensor to calculate power accurately. The sensor positioned on the rear pulley works magnetically and measures the speed of the chain. The chain stay sensor (power sensor) calculates the tension of the chain by measuring the vibration as the chain passes over the sensor. The Power Output Sensor also has built-in cadence and speed sensors.
How Quick Is the Set-Up?
It couldnt be easier. All you have to do is enter once, when setting up the unit a set of key factors: chain length, chain weight and the length between the bottom bracket and rear wheel axles. And then away you go. Or, you may use the default settings to get started (Chain weight 304 g and length 1473 mm and Span length 420 mm). Precision pedal power every time!
Does Chain Slap Affect the Results?
No. Because the chain is taut as you pedal, the Power measurement is unaffected by chain slap. The only time excessive chain slap occurs is when youre not pedaling and no power is generated.
How Accurate is this System?
Highly accurate. Power Output Sensor and the Polar S720 gives you a readout in real time of the power in watts, you generate with a ± 10 % accuracy. The most useful measurement range is between 50 and 1000 Watts power and 0 120 rpm cadences. Momentary differences may rarely occur, but they keep within a ± 10 % accuracy.
How Does this System Measure Pedaling Efficiency?
A pedal stroke generates peak power as the foot pushes down on the pedal. In one rotation there are two power peaks: the first as you push down with the right foot and pull up with the left, and the second when you push down with the left foot and pull up with the right. In between, your power output is decreased. The Power Output Sensor measures the maximum and minimum power values and calculates your L/R Balance and Pedaling Index, using a cadence sensor on the right pedal to mark the right side.
Why Choose the Polar Power Output Sensor?
No hub, wheel or crank change
The system measures power direct from the chain no need to change hubs, wheels or cranks unlike other models.
Polar the lightweight choice
The Polar S-Series Heart Rate Monitor and the bike sensors weighs in at just 276 grams when installed - compared to over 550 grams for other models.