Ergomo Validity shot down....

[Bob Edberry]

Don't know if anyone saw this, but something that I have suspected all along. Someone posted it on the wattage forum. Bad news for all you ergomo owners out there.....

IJSPP, 2(3), September 2007, Copyright (c) 2007 Validity and Reproducibility of the Ergomo(r)Pro Power Meter ComparedWith the SRM and Powertap Power Meters Sébastien Duc ; Vincent Villerius; William Bertucci ; Frédéric GrappeFull Article Table of Contents for Vol. 2, Iss. 3 AbstractPurpose: The Ergomo¨Pro (EP) is a power meter that measures poweroutput (PO) during outdoor and indoor cycling via 2 optoelectronicsensors located in the bottom bracket axis. The aim of this study wasto determine the validity and the reproducibility of the EP comparedwith the SRM crank set and Powertap hub (PT). Method: The validity ofthe EP was tested in the laboratory during 8 submaximal incrementaltests (PO: 100 to 400 W), eight 30-min submaximal constant-power tests(PO = 180 W), and 8 sprint tests (PO > 750 W) and in the field during8 training sessions (time: 181 ± 73 min; PO: ~140 to 150 W). Thereproducibility was assessed by calculating the coefficient of POvariation (CV) during the submaximal incremental and constant tests.Results: The EP provided a significantly higher PO than the SRM and PTduring the submaximal incremental test: The mean PO differences were+6.3% ± 2.5% and +11.1% ± 2.1%, respectively. The difference wasgreater during field training sessions (+12.0% ± 5.7% and +16.5% ±5.9%) but lower during sprint tests (+1.6% ± 2.5% and +3.2% ± 2.7%).The reproducibility of the EP is lower than those of the SRM and PT(CV = 4.1% ± 1.8%, 1.9% ± 0.4%, and 2.1% ± 0.8%, respectively).Conclusions: The EP power meter appears less valid and reliable thanthe SRM and PT systems.

 

[Squint]

It's nothing we don't already know.

The only people who believe otherwise have a financial interest in Ergomo or are in denial because they can't cope with the fact that they wasted their money.

 

[walsallscott]

It's nothing we don't already know.

The only people who believe otherwise have a financial interest in Ergomo or are in denial because they can't cope with the fact that they wasted their money.

I've got an ergomo.... I'm not really worried about how they compare to SRM/PT. As long as the ergomo produces consistent results and my testing (i.e determintation of FTP etc) has been done using the same piece of equipment then why should I be worried ????

 

[beerco]

As long as the ergomo produces consistent results and my testing (i.e determintation of FTP etc) has been done using the same piece of equipment then why should I be worried ????

"The reproducibility of the EP is lower than those of the SRM and PT(CV = 4.1% ± 1.8%, 1.9% ± 0.4%, and 2.1% ± 0.8%, respectively)"

Not so good.

 

[jbvcoaching]

I've got an ergomo.... I'm not really worried about how they compare to SRM/PT. As long as the ergomo produces consistent results and my testing (i.e determintation of FTP etc) has been done using the same piece of equipment then why should I be worried ????

Mainly because you're not going to have that particular piece of equipment forever. So in the future, when you reinstall your Ergomo, get a new one, or get a different powermeter, it will be very challenging (if not impossible) to compare data from different seasons. The benefit of a powermeter that's accurate is, you just keep using accurate powermeters, and you can fully utilize all your historical data without caveats.

For example, there's a guy on the wattage list right now who was using an uncalibrated SRM amateur in 1999, it told him he did 423W for a ~20 minute TT back then. It's only 8 years later, but his current SRM Dura Ace (also uncalibrated) is telling him he's producing around 25% less power for that duration now.

If he believes these numbers, then it drives him to perhaps train (and view himself) differently than if he calibrates the current SRM, and accepts that he'll never know how many "real" watts he did back in 1999.

Longer term data analysis is one of the biggest values in using a powermeter, using an inaccurate PM really negates that value.

Besides that, the Ergomo isn't even consistent (with itself) due to the R/L balance issue. One of my clients owns an Ergomo, a PT, and an iBike. We know through a variety of tests that he has a cadence-related L/R imbalance. He's right leg dominant at lower (under 90) cadences, left leg dominant at higher cadences (over 100). So his TT data looks different than (for example) his crit data depending on which PM he's on, even though everything works for overall load because he's got them fairly consistent with each other. Unfortunately, every time we test or see a new high power, we have to go through the extra steps of asking "which powermeter" and qualifying it. Kind of a PITA.

Small (5% or less) differences like this also make it tough to use the PM for assessing small gains in fitness, or for aero testing (if that's something you're into).

So if you're only going to use this particular Ergomo, and you're going to use it on the same installation for as long as you race and train with a PM, and you don't care about long term data analysis, aero testing, or measuring small changes in power for different durations, then you probably have nothing to worry about. That then kind of begs the question, exactly what are you using a powermeter for, and can you use a watch, PE, and a local climb for the same thing?

 

[Roadie_scum]

Mainly because you're not going to have that particular piece of equipment forever. So in the future, when you reinstall your Ergomo, get a new one, or get a different powermeter, it will be very challenging (if not impossible) to compare data from different seasons. The benefit of a powermeter that's accurate is, you just keep using accurate powermeters, and you can fully utilize all your historical data without caveats.

For example, there's a guy on the wattage list right now who was using an uncalibrated SRM amateur in 1999, it told him he did 423W for a ~20 minute TT back then. It's only 8 years later, but his current SRM Dura Ace (also uncalibrated) is telling him he's producing around 25% less power for that duration now.

If he believes these numbers, then it drives him to perhaps train (and view himself) differently than if he calibrates the current SRM, and accepts that he'll never know how many "real" watts he did back in 1999.

Longer term data analysis is one of the biggest values in using a powermeter, using an inaccurate PM really negates that value.

Besides that, the Ergomo isn't even consistent (with itself) due to the R/L balance issue. One of my clients owns an Ergomo, a PT, and an iBike. We know through a variety of tests that he has a cadence-related L/R imbalance. He's right leg dominant at lower (under 90) cadences, left leg dominant at higher cadences (over 100). So his TT data looks different than (for example) his crit data depending on which PM he's on, even though everything works for overall load because he's got them fairly consistent with each other. Unfortunately, every time we test or see a new high power, we have to go through the extra steps of asking "which powermeter" and qualifying it. Kind of a PITA.

Small (5% or less) differences like this also make it tough to use the PM for assessing small gains in fitness, or for aero testing (if that's something you're into).

So if you're only going to use this particular Ergomo, and you're going to use it on the same installation for as long as you race and train with a PM, and you don't care about long term data analysis, aero testing, or measuring small changes in power for different durations, then you probably have nothing to worry about. That then kind of begs the question, exactly what are you using a powermeter for, and can you use a watch, PE, and a local climb for the same thing?

Bravo! An excellent response.

 

[Bob Edberry]

It's nothing we don't already know.

The only people who believe otherwise have a financial interest in Ergomo or are in denial because they can't cope with the fact that they wasted their money.

NGART? Any response? Let me guess... I'll bet it will be a positive one for ergomo...

BE

 

[patrick_]

Has anyone here read the complete paper? Did they really find out what they think the found out?

The conclusions in the abstract don't have to be correct just because some journal decided to print this paper.

 

[tmctguer]

my Ergomo Pro on Bike #1 (Specialized Roubaix Pro) does show much higher wattage numbers than my Powertap Pro on Bike #2 (Cannondale CADD 7). curiously enough, my Powertap shows numbers that are very consistent to my old Polar Power Meter.

but i sure like the Ergomo's display and altimeter. for me (a 50 year old recreational, but fast cyclist), i am happy because i really don't use my power meters like a professional would. But i am not happy that i spent $1,600 on a power meter that reads higher than it should !!

 

[Squint]

NGART? Any response? Let me guess... I'll bet it will be a positive one for ergomo...

He's too busy hiring girls for Interbike to distract people from his product's deficiencies.

 

[tmctguer]

let me add one more thought about the Ergomo before i just dismiss it completely.......i was also curious to find out that my Polar power unit read higher on my Specialized than the one on my Cannondale.

so, is it possible to generate more watts on one bike than you do on another?

 

[Alex Simmons]

let me add one more thought about the Ergomo before i just dismiss it completely.......i was also curious to find out that my Polar power unit read higher on my Specialized than the one on my Cannondale.

so, is it possible to generate more watts on one bike than you do on another?

if they are the same set up, unlikely. if one is a TT bike and one a road race bike, then quite possibly. sounds more like a calibration problem though.

 

[POGATA]

Don't know if anyone saw this, but something that I have suspected all along. Someone posted it on the wattage forum. Bad news for all you ergomo owners out there.....

IJSPP, 2(3), September 2007, Copyright (c) 2007 Validity and Reproducibility of the Ergomo(r)Pro Power Meter ComparedWith the SRM and Powertap Power Meters Sébastien Duc ; Vincent Villerius; William Bertucci ; Frédéric GrappeFull Article Table of Contents for Vol. 2, Iss. 3 AbstractPurpose: The Ergomo¨Pro (EP) is a power meter that measures poweroutput (PO) during outdoor and indoor cycling via 2 optoelectronicsensors located in the bottom bracket axis. The aim of this study wasto determine the validity and the reproducibility of the EP comparedwith the SRM crank set and Powertap hub (PT). Method: The validity ofthe EP was tested in the laboratory during 8 submaximal incrementaltests (PO: 100 to 400 W), eight 30-min submaximal constant-power tests(PO = 180 W), and 8 sprint tests (PO > 750 W) and in the field during8 training sessions (time: 181 ± 73 min; PO: ~140 to 150 W). Thereproducibility was assessed by calculating the coefficient of POvariation (CV) during the submaximal incremental and constant tests.Results: The EP provided a significantly higher PO than the SRM and PTduring the submaximal incremental test: The mean PO differences were+6.3% ± 2.5% and +11.1% ± 2.1%, respectively. The difference wasgreater during field training sessions (+12.0% ± 5.7% and +16.5% ±5.9%) but lower during sprint tests (+1.6% ± 2.5% and +3.2% ± 2.7%).The reproducibility of the EP is lower than those of the SRM and PT(CV = 4.1% ± 1.8%, 1.9% ± 0.4%, and 2.1% ± 0.8%, respectively).Conclusions: The EP power meter appears less valid and reliable thanthe SRM and PT systems.

What have you suspected?

Why is it bad news for Ergomo owners?

Do you believe that the one Ergomo Pro was installed properly and that the one SRM(was it an amateur/pro/science) and the one Powertap(which model) were accurate?

I have an Ergomo Pro and a SRM Dura-Ace, why have I not noticed the difference in the power numbers between the two?

 

[POGATA]

It's nothing we don't already know.

The only people who believe otherwise have a financial interest in Ergomo or are in denial because they can't cope with the fact that they wasted their money.

I don`t know! I have no financial interest in Ergomo! I have even wasted twice as much money on a SRM which is just as "inaccurate" as the Ergomo!

 

[Roadie_scum]

What have you suspected?

Why is it bad news for Ergomo owners?

Do you believe that the one Ergomo Pro was installed properly and that the one SRM(was it an amateur/pro/science) and the one Powertap(which model) were accurate?

Yeah I believe the scientists... if you want to check on their methods look up the paper. I did. They used the science SRM with 20 strain gauges.

I have an Ergomo Pro and a SRM Dura-Ace, why have I not noticed the difference in the power numbers between the two?

Because it is completely impossible to ride both of these at the same time? Or because they both very accurately read zero when you aren't riding them?

I *hate* it when I realise that I wasted my money.

 

[Speedskater]

Yeah I believe the scientists... if you want to check on their methods look up the paper. I did. They used the science SRM with 20 strain gauges.



Because it is completely impossible to ride both of these at the same time? Or because they both very accurately read zero when you aren't riding them?

I *hate* it when I realise that I wasted my money.

Maybe he got it wrong and meant the Octalink Pro version of the SRM.

If this paper holds true, I also had wasted may money, but the objections POGATA mentioned could be correct. As we all know, the correct installation of a Ergomo is a real PITA. Why should we take a correct procedure as granted, just because scientist did it? Additionally, wasn´t there a side-to-side-comparison of Ergomo, SRM and PT some time ago in which they didn´t differ? Anyway, I will be at the Eurobike on Thursday an will ask Ergomo (the manufacturer, not just the distributor for the US) some questions.

 

[PaulMD]

Mainly because you're not going to have that particular piece of equipment forever. So in the future, when you reinstall your Ergomo, get a new one, or get a different powermeter, it will be very challenging (if not impossible) to compare data from different seasons. The benefit of a powermeter that's accurate is, you just keep using accurate powermeters, and you can fully utilize all your historical data without caveats.

For example, there's a guy on the wattage list right now who was using an uncalibrated SRM amateur in 1999, it told him he did 423W for a ~20 minute TT back then. It's only 8 years later, but his current SRM Dura Ace (also uncalibrated) is telling him he's producing around 25% less power for that duration now.

If he believes these numbers, then it drives him to perhaps train (and view himself) differently than if he calibrates the current SRM, and accepts that he'll never know how many "real" watts he did back in 1999.

Longer term data analysis is one of the biggest values in using a powermeter, using an inaccurate PM really negates that value.

Besides that, the Ergomo isn't even consistent (with itself) due to the R/L balance issue. One of my clients owns an Ergomo, a PT, and an iBike. We know through a variety of tests that he has a cadence-related L/R imbalance. He's right leg dominant at lower (under 90) cadences, left leg dominant at higher cadences (over 100). So his TT data looks different than (for example) his crit data depending on which PM he's on, even though everything works for overall load because he's got them fairly consistent with each other. Unfortunately, every time we test or see a new high power, we have to go through the extra steps of asking "which powermeter" and qualifying it. Kind of a PITA.

Small (5% or less) differences like this also make it tough to use the PM for assessing small gains in fitness, or for aero testing (if that's something you're into).

So if you're only going to use this particular Ergomo, and you're going to use it on the same installation for as long as you race and train with a PM, and you don't care about long term data analysis, aero testing, or measuring small changes in power for different durations, then you probably have nothing to worry about. That then kind of begs the question, exactly what are you using a powermeter for, and can you use a watch, PE, and a local climb for the same thing?

I haven't read anything about calibration of a powertap. After reading this story: can I calibrate my powertap, and how often should it be done?

 

[RChung]

I haven't read anything about calibration of a powertap. After reading this story: can I calibrate my powertap, and how often should it be done?

You can't re-calibrate a PT yourself but you can check its calibration, and then either send it back to Saris for re-calibration or, under certain circumstances, correct past data files for calibration error.

You can find a general description of the procedure by googling up "power tap stomp test" (though I wouldn't actually recommend the usual stomp procedure).

 

[POGATA]

Yeah I believe the scientists... if you want to check on their methods look up the paper. I did. They used the science SRM with 20 strain gauges.



Because it is completely impossible to ride both of these at the same time? Or because they both very accurately read zero when you aren't riding them?

I *hate* it when I realise that I wasted my money.

Where??

 

[Roadie_scum]

Where??

Here