Polar Power Sensor

Power Up Your Training!

With the Polar Power Option - for the Polar S725, S625X, S720i and S710


Now you can combine the benefits of training with heart rate and power. Power data is one of the most important pieces of cycling performance data. With the power option for the Polar S625X, S725, S720i, and S710 - your power data will be downloaded from your HRM along with your heart rate data. This allows you to visualize the relationship between your heart rate and power. The power option also measures your left and right pedaling ratio and overall efficiency. Best of all, there are no wheel or hub changes needed, and the unit weighs just 225 grams.

The Polar Power Sensor is an accessory that can be used along with the Polar S625X, S725, S720i, and S710 heart rate monitors, and gives you access to power data - the ultimate in training information. Click here for more information on the various models of Polar Heart rate monitors.

Polar Power Sensor Kit - Sale Price: $349.95

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How it Works
polar power sensor kit for S720i

The Polar Power sensor derives wattage from the chain, not from the crank or hub as other models do. The system works by measuring two key factors:

Chain Tension - measured using a sensor on the chain stay
Chain Speed - measured 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 the HRM to calculate watts very accurately. The sensor positioned on the rear pulley works magnetically and measures the speed of the chain. The chain stay sensor calculates the tension of the chain by measuring the vibration as it passes over the sensor (The user will enter one time during set up: chain length, chain weight and the measurement between the bottom bracket axle to the rear wheel axle. A chart in the manual will help provide some standard parameters.)


How the Unit Measures Pedaling Efficiency

There is a cadence sensor also built into the system. A cadence magnet is located on the bottom of the drive side crank, when the crank is in the 9 O'clock position, near the pedal. This provides real time cadence to the S720i.

A normal pedal stroke will generate max power when the foot pushes downward on the pedal. Example: I push my right foot down and pull up on the left and I get a power spike. When I push down on the left, and pull up on the right, I get another power stroke. In between is a spilt second "dead spot" where power disappears. The S720i measures the spikes and calculates the difference between pedal strokes. This is converted into a percentage measurement. It uses the cadence sensor on the right foot to mark the right side from there, it provides an index for the right and left.


Example:
Right side pedaling generates 300 watts
Left side pedaling generates 300 watts
Pedaling efficiency 50% right 50% left

PC Coach Compatibility

Your power data will be downloaded directly into your PC Coach software!

If you would like to purchase the Polar Power Sensor, or any other training product, please visit our store, or call us at 1-800-522-6224 for more information.

If you have already purchased the Polar Power sensor, visit the Polar site for a video on proper installation of your power sensor.

Click here to see installation demo.

 

Why Power and Heart Rate Training?

So how does the added element of power monitoring play into training? Power output does not replace heart-rate measurement, but is intended to be used in conjunction with it. The main benefit is that it allows you to actually measure workload rather than make a guess at it based soley on heart rate, which can be affected by temperature (heat or cold) and other factors. Within any given ride you can easily evaluate performance based on power output. At any point in the ride you can know if they are performing at, below or above previous best performance.

Focus on power for intervals, hill training, sprint training, and all anaerobic workouts. Often in these efforts heart rate lags behind the intensity and the resulting change in heart rate. For example, at the start of an interval, heart rate takes several seconds, or even minutes to catch up with energy demands being expended. During a short sprint it will never give an accurate measurement of the effort.... tell me more.

The above two paragraphs are an excerpt from the article Power Training 101 by Edmund Burke, Ph.D.

Read the entire Power Training 101 article here.

Power Training 101 originally appeared on the Polar USA web site, and is reproduced here with permission from Polar.

 

If you need information on installing your Polar Power kit, visit the Polar USA web site, where they have tips for a successful installation http://www.polarusa.com/consumer/powerkit/installation.asp

The Polar site also has a video that demonstrates the proper installation of your power sensor.

Click here to see installation demo.

 
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