TE PS - Torque Effectiveness & Pedal Smoothness

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TE PS - Torque Effectiveness & Pedal Smoothness

Postby the5krunner » Sat Apr 16, 2016 3:57 pm

Torque Effectiveness (TE) & Pedal Smoothness (PS) from Garmin Fit file (Garmin Vector, Favero BePro, ROTOR INpower)

Can someone remind me please:

TE and PS are both in the official FIT file spec I believe.

1. should the standard ST importer import them
2. do I then need any plugin to display them

3. does OMBs FIT importer import them
4. do I then need any plugin to display them (I have liverecording )

5. Where can I then actually see and use them
6. ideally I want to use OVERLAY to compare them but that's a question too far.

thank you !!
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Re: TE PS - Torque Effectiveness & Pedal Smoothness

Postby old_man_biking » Sun Apr 17, 2016 1:56 pm

Garmin FIT Devices plugin imports them, Custom Data Tracks Plugin displays them.
OMB
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Re: TE PS - Torque Effectiveness & Pedal Smoothness

Postby tndmbkr » Mon Apr 18, 2016 2:21 am

I love watching charts.
But I have never understood what I am looking at, when I have a chart of Torque Effectiveness and Pedal Smoothness on my screen.

According to cyclinganalytics.com TE and PS are calculated by the powermeter, and transmitted with ANT+ to a compatible bikecomputer.
The bikecomputer does not calculate anything, It only stores these data in the FITfile.
Every second once.

A typical powermeter may use a sampling rate of 45Hz to measure torque (NOT power!) and cadence.
That is 30 measurements per crank rotation (when the cadence = 90 rpm)
But the ANT+ protocol only allows a broadcast of data once a second.
That is after every one and a half crank rotation.
So you never get live values, but average values transmitted to your bike computer.

Below is a chart which shows the torque being applied to a pedal by a leg in a rotation of the cranks.
When Pedal Smoothness is perfect.
It starts off positively on the downward movement, but there is a negative component in the second half of the rotation if the pedal isn’t completely unloaded or lifted up.
Image
TE is a measure for the proportion of positive torque and negative torque.
No problems so far.

But the data samples which are sent to the bike computer sometimes contain more negative areas than other datasamples.

My problem:
Torque values vary very much across the rotation of a crank.
However torque is measured at different stages of a crank revolution.
Only the average value of more than one crank revolution is transmitted to the bike computer.
In order to measure a meaningful TE, the powermeter should transmit more than one value per crank rotation.
So you can use values per crank position for your analysis.
Last edited by tndmbkr on Mon Apr 18, 2016 11:17 am, edited 1 time in total.
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Re: TE PS - Torque Effectiveness & Pedal Smoothness

Postby the5krunner » Mon Apr 18, 2016 2:59 am

ROTOR INpower 3D+ is 200Hz

i'm looking at differences in PE/TE on elliptical chainrings and yes low sampling will introduce inaccuracy eg powertap p1 pedals are more frequent than garmin vector (I am told) and so more accurate on elliptical chainrings
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Re: TE PS - Torque Effectiveness & Pedal Smoothness

Postby texmurphy » Mon Apr 18, 2016 8:48 am

tndmbkr wrote:...A typical powermeter may use a sampling rate of 45Hz to measure torque (NOT power!) and cadence.
That is 30 measurements per crank rotation (when the cadence = 90 rpm)
But the ANT+ protocol only allows a broadcast of data once a second.
That is after every one and a half crank rotation.
So you never get live values, but average values transmitted to your bike computer...

You could get a PowerPod (or Newton) with PowerStroke which records 18 times a second and displays using Isaac from iBike. However format of ibr file is proprietary and not available to ST.
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