Tacx IDT and power measurements

[capeofstorms]

Hi,

 

Does anyone know how the TACX indoor trainer derive it's power measurements. If you disconnect the the cadence/speed pickup, but keep the head unit connected to the brake unit, the head unit still displays power.

 

The reason why I'm asking is that I would like to NOT use the Tacx sensor, but use ONLY the garmin 500 cadence and speed sensor. In this way I won't find the need to have 2 cadence sensors mounted to my crank arm.

 

Coming back to my question. Where does this power measurement come from without speed being an input to the tacx?

[usxorf]

With the flow, speed is an input, estimated from flywheel (?) rotations. Combined with the resistance setting, it estimates power/watts.

[capeofstorms]

Hi,

 

Thanks man. So if it is from the flywheel then I assume I can dispense of the cadence sensor and I will still be able to read watts?

[usxorf]

Yes, mine displays watts with no sensor.

[Santa C]

Are the Watts measured on the Tacx Flow accurate?

 

I have put my bike with the Cycleops PM on the flow IDT and have seen to very different readings...one from my joule and the other from the flow IDT computer.

 

The flow over reads by 50watts...how do u calibrate your flow be make sure it is correct?