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Power Output measure gives sense to your training but how to measure it ?
As power is mechanic value, to measure it, we need sensor for mechanic measurement.
Nowaday all powermeters devices use mechanic sensors as use you can find in the Industry.
Many sensors are available, to sum up we will present you in this page 2 of them The Powertap (Hub with mechanic sensor) and the POLAR sensor (without direct sensor).
POWERTAP :
The PT hub is available in Two versions : Aluminum hub (576g) and Carbon Hub (416g). For both versions, the power accuracy is /- 2% which place the PT on the header group accurate sensors.
It you’ve understood well, to train with the PT, you just need to change the wheel and use a specific cycle computer.
Different wheels are available with PT; you can directlty order to Cycleops Bontrager, HED, Zipp (TT wheel available) or you can just order the basic PT and ask your favorite bike shop to build your specific wheel .
The Powertap is in fact a rear wheel hub with 8 strain gauges. These sensors will measure the effort applied on the hub (distortion).
The data is sent through a cable or via wireless transmission (depending of the version) to the Cycle Computer (called Cervo = Brain in phonetic French).
So, to measure your power with Powertap, you need a specific rear wheel with PT hub, the Cervo (PT brain) and the Heart Rate monitor strap.
During the first workout with PT, the first impression is the ease to ride with PT.
The Cycle computer is identical to the other basics cycle computer with just an additional display line.
The top of this device is the non utility to calibrate it before each session, the PT managed itself his calibration. And if during the workout an important climatic change occurs, the PT will automatically recalibrate his zero during your ride.
For example, on SRM powermeter, you need to calibrate the Powermeter before each ride.
Powertap is delivrered with his own analysis software called PowerAgent (Windows, Mac compatible and Linux).
The PT soft is available in different Available in 6 languages (English, Dutch, German, French, Italian and Spanish).
POLAR power output sensor
The Finnish Heart Rate Manufacturer POLAR propose since 2007 a new power output sensor the CS600 .
The CS600 is based on the old S720 Power sensor combined now with a real cyclecomputer which have the most advanced HR functions (Target Zones, Tests to define HRmax abnd training zones, R-R Recorder and so on …).
The principle of polar power measurement is based on a new way of cycling effort measure. The sensor will not measure any distortion with strain gauge but through electromagnetic sensor, he will measure tension chain and speed chain. The combination of these 2 values will calculate your power.
To mount your POLAR sensor, you will need some time even if there is on the new version less cable than on S720 sensor (wireless transmission between sensor and cyclecomputer). Some input datas are needed to calculate well your wattage : the chain dimension and the chain weight.
The CS600 is delivered with the new POLAR analysis software (Vista Compatible) called PROTRAINER 5 which have all the most advanced HR analysis system. With this software, you could see your ride and calculate your stats (time in training zones, training load, …). Moreover you could make some fitness tests to determine your fitness level, your performance indicator or your Max HR).
The CS600 is less accurate /- 10% instead of /-2% for the Powertap but with a more affordable price (50% lower). It’s up to you to define the sensor your want according to your budget.
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