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The pedaling technique thread

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Sep 23, 2010
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CoachFergie said:
Is there anything published that validates the iCrank tool? Judging by some of the claims made on their site that would be a good place to start.
Of course not. I do believe the AIS has been playing with it. You snooze you lose, perhaps.
 
Apr 21, 2009
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FrankDay said:
Of course not. I do believe the AIS has been playing with it. You snooze you lose, perhaps.
Of course they are:rolleyes:

So no validation of the product. Makes it hard to trust the data. You do have to jump through a few hoops to ensure the validity and reliability of power meter data. Your mate, the MIT grad who didn't perform a zero offset before a FTP test can tell you all about that.
 
Sep 23, 2010
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CoachFergie said:
So no validation of the product. Makes it hard to trust the data. You do have to jump through a few hoops to ensure the validity and reliability of power meter data. Your mate, the MIT grad who didn't perform a zero offset before a FTP test can tell you all about that.
So, let me get this straight. You are a big proponent of athletes using a device that has been around for about 25 years and in common use for about 15 years that in all of this time there hasn't been a single shred of scientific evidence that the device makes a scintilla of difference for the athlete and you are concerned that a different device that has additional capability but that hasn't even come on to the market yet doesn't have any scientific validation? If you say so.
 
Apr 21, 2009
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FrankDay said:
So, let me get this straight. You are a big proponent of athletes using a device that has been around for about 25 years and in common use for about 15 years that in all of this time there hasn't been a single shred of scientific evidence that the device makes a scintilla of difference for the athlete and you are concerned that a different device that has additional capability but that hasn't even come on to the market yet doesn't have any scientific validation? If you say so.
More trolling.

POWER METERS DO NOTHING, NADA, ZIPPO TO MAKE A DIFFERENCE!!!

Don't make me petition the mods to put a size 8 font on to make this any clearer.

A good power meter will however measure power with a high degree of validity and reliability if you follow a few simple steps and have the calibration checked at least every six months as you would for any measuring device.
 
Mar 10, 2009
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FrankDay said:
Anyhow, the iCranks people have just upgraded their software and it now has a nice feature, they have included a box to show how much power is being lost on each revolution of the cranks. See below.



Next, at this point in time, the rider is losing over 10% of his positive propulsive efforts from the negative wattage on the upstroke (156 watts positive, 18 watts negative, 138 watts total).

Next, notice the size of the power at 6 o'clock compared to 12, it is much larger than the 12 o'clock number. I think for this rider, the biggest gains will come from working on improving the forces across the top (without changing anything else) and, of course, improving the right leg to be the equal of the left.
This is not the only power that is lost on each revolution of the cranks. How does this rider improve his forces across the top and how can he balance power output from both legs. Are you certain that PM is set up correctly, it is unusual to see negative torque at 12.
 
Sep 23, 2010
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coapman said:
Are you certain that PM is set up correctly, it is unusual to see negative torque at 12.
Yes. It is what it is. One can't correct something unless one knows it is there. Unless this rider has some physical issues correcting this imbalance and these negative forces should be quite easy with independent cranks. It will be very difficult with connected cranks.
 
Apr 21, 2009
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FrankDay said:
Yes. It is what it is. One can't correct something unless one knows it is there. Unless this rider has some physical issues correcting this imbalance and these negative forces should be quite easy with independent cranks. It will be very difficult with connected cranks.
Not what Noel asked. Where is the validation of the iCrank? Whole lot of marketing claims on their web site.
 
Sep 23, 2010
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CoachFergie said:
Not what Noel asked. Where is the validation of the iCrank? Whole lot of marketing claims on their web site.
Actually, he asked me if I were certain it was set up properly.

Regarding validation, I am currently doing what you have done, riding the iCranks on another power meter (Velotron, about as accurate as you can get) to confirm it conforms well to a standard power meter, at least as regards the total power seen. It does.
 
May 13, 2011
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FrankDay said:
Actually, he asked me if I were certain it was set up properly.

Regarding validation, I am currently doing what you have done, riding the iCranks on another power meter (Velotron, about as accurate as you can get) to confirm it conforms well to a standard power meter, at least as regards the total power seen. It does.
Frank,

How about submitting some dual ride files to Robert Chung for his careful analysis if you really wish to see how the two stack up. "Looks good to me" probably won't cut it with this crowd but Robert's close scrutiny would go a long ways towards acceptance.

Hugh
 
Mar 18, 2009
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sciguy said:
Frank,

How about submitting some dual ride files to Robert Chung for his careful analysis if you really wish to see how the two stack up. "Looks good to me" probably won't cut it with this crowd but Robert's close scrutiny would go a long ways towards acceptance.

Hugh
How will anyone make sure Day did not provide doctored files? He has done it before.
 
Apr 21, 2009
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BroDeal said:
How will anyone make sure Day did not provide doctored files? He has done it before.
Ha ha "Doctored". Well played! Robert Chung did find sections of power data repeating itself:rolleyes:

Yes we await publication of validation in the scientific media.
 
May 13, 2011
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BroDeal said:
How will anyone make sure Day did not provide doctored files? He has done it before.
In fairness to Frank, that was Joaquim who seemed to have been the one who fabricated the composite files that proved his tremendous power gains.

Hugh
 
Sep 23, 2010
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sciguy said:
In fairness to Frank, that was Jaquin (sp?) who seemed to have been the one who fabricated the composite files that proved his tremendous power gains.

Hugh
Actually, Joaquim didn't fabricate anything. If you will remember that was in a thread started by someone who went over and rode up this climb with him and remarked he simply rode away from him. He believes someone who had access to his computer modified that file to embarrass him. Joaquim luckily still had the data in his Powertap and was able to download again and he forwarded it to me and Dr. Chung although he asked us to not share it with anyone else as he was so disgusted with how he was treated when he showed up.
 
Sep 23, 2010
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This is not directly related to anything but I think is interesting as it shows the kind of adaption that can occur after 50 hours of PowerCranks training. This was sent to us by a customer today comparing a climb he did on his first PowerCranks outing and the "same" climb after 50 hours.

One comment I had when I saw this was very few people would have been able to do that well on the first ride as he was able to complete that without stopping. I was told that he had listened to us and was riding 150mm crank length, which makes the PC's a lot easier. Both rides are on 150 crank length.
 
Mar 10, 2009
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FrankDay said:
Yes. It is what it is. One can't correct something unless one knows it is there. Unless this rider has some physical issues correcting this imbalance and these negative forces should be quite easy with independent cranks. It will be very difficult with connected cranks.
Can you explain how powercranks will increase this riders torque application on the downstroke to correct the imbalance.
 
Sep 23, 2010
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coapman said:
Can you explain how powercranks will increase this riders torque application on the downstroke to correct the imbalance.
Assuming there is no physical issue preventing balance and this is just the residual from an inadequately rehabbed old injury, time in the saddle (since the strong leg cannot assist the weak leg the weak leg has to do more work compared to when on regular cranks) and some one legged drills if it isn't self correcting over time should do it.
 
Apr 21, 2009
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FrankDay said:
Regarding validation, I am currently doing what you have done, riding the iCranks on another power meter (Velotron, about as accurate as you can get) to confirm it conforms well to a standard power meter, at least as regards the total power seen. It does.
Very good, and what about the validation of force vector data around the pedal stroke?
 
Sep 23, 2010
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CoachFergie said:
Very good, and what about the validation of force vector data around the pedal stroke?
That will have to be left to others as I don't have force plate pedals available to me to do that validation. As long as the total power validates I will presume the parts that add up to the total are pretty close.
 
Apr 21, 2009
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FrankDay said:
That will have to be left to others as I don't have force plate pedals available to me to do that validation. As long as the total power validates I will presume the parts that add up to the total are pretty close.
A $US3000 tool that is pretty close:D
 
Sep 23, 2010
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CoachFergie said:
A $US3000 tool that is pretty close:D
Close enough. Really, do you have data that the outcome an athlete gets from using the $5k SRM model is better than the outcome that is achieved using a much cheaper powertap?

The problem is that at some point additional accuracy adds zero improvement. Do we need to know our power to the nanowatt? The enemy of good enough is, sometimes, better and, almost always, perfect.
 
May 13, 2011
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Frank,

Does your new Icrank still show you to have a substantial imbalance just as the initial unit did?

Hugh
 
Apr 21, 2009
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FrankDay said:
Close enough. Really, do you have data that the outcome an athlete gets from using the $5k SRM model is better than the outcome that is achieved using a much cheaper powertap?
Better precision, better accuracy, better service (when my PT crapped out it had to be sent to US and the Oceania SRM service centre is in Christchurch), can change the slope if calibration is out, is a crank based PM so can be used with any wheelset and is easy to switch between bikes.

The problem is that at some point additional accuracy adds zero improvement. Do we need to know our power to the nanowatt? The enemy of good enough is, sometimes, better and, almost always, perfect.
If I had any product or service I wanted to test I would want the best measurement money could buy.
 
Sep 23, 2010
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CoachFergie said:
If I had any product or service I wanted to test I would want the best measurement money could buy.
Sure, if you didn't have to pay for it or had "unlimited" resources (it would give you bragging rights) but if you had to pay for it, didn't have unlimited resources, and it didn't make a difference… then what?
 
Apr 21, 2009
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FrankDay said:
Sure, if you didn't have to pay for it or had "unlimited" resources (it would give you bragging rights) but if you had to pay for it, didn't have unlimited resources, and it didn't make a difference… then what?
Make exaggerated claims on the Internet I assume.
 
Sep 23, 2010
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A new study to add to the Leirdahl study (link)
Results: Mean work rate was 279 W, mean FCC was 93.1 rpm, and mean GE was 21.7%. FE was 0.47 and 0.79 after correction for inertial forces; DC was 27.3% and 25.7%, respectively. DC size correlated better with GE (r = 0.75) than with the FE ratio (r = 0.50). Multiple regressions revealed that DC size was the only significant (P = 0.001) predictor for GE. Interestingly, DC size and FE ratio did not correlate with each other.
new study link here
The most notable results were as follows: gross efficiency (r = -0.72, P < 0.05 at 250 W) was inversely correlated with the ratio of minimum to peak torque, particularly at higher work rates. There was a highly significant inverse correlation between delta efficiency and average minimum torque at 200 W (r = -0.76, P < 0.01). Cycling experience was positively correlated with delta efficiency and gross efficiency, although experience and the ratio of minimum to peak torque were not related. These results show that variations in pedalling technique may account for a large proportion of the variation in efficiency in trained cyclists.
 
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